SATNET Asia Training Manual. Integrated Pest Management

Transcription

1 SATNET Asia Training Manual Integrated Pest Management

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3 SATNET Asia Training Manual Integrated Pest Management

4 Copyright CAPSA-ESCAP 2015 All rights reserved ISBN: The Network for Knowledge Transfer on Sustainable Agricultural Technologies and Improved Market Linkages in South and South-East Asia (SATNET Asia) aims to support innovation by strengthening South-South dialogue and intraregional learning on sustainable agriculture technologies and trade facilitation. Funded by the European Union, SATNET facilitates knowledge transfer through the development of a portfolio of best practices on sustainable agriculture, trade facilitation and innovative knowledge sharing. Based on this documented knowledge, it delivers a range of capacity-building programmes to network participants. SATNET Asia is implemented by the Centre for Alleviation of Poverty through Sustainable Agriculture (CAPSA) in collaboration with AVRDC The World Vegetable Center, the Asian and Pacific Centre for Transfer of Technology (APCTT), the Food Security Center of the University of Hohenheim, Germany and the Trade and Investment Division of the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP). This training manual is an outcome of collaborative work by SATNET Asia on sustainable agricultural technologies and trade facilitation. Editing: Mahesh Uniyal Production: Fetty Prihastini, CAPSA-ESCAP Design: Fransisca A. Wijaya, CAPSA-ESCAP Cover photo: CAPSA-ESCAP This training manual has been produced with the assistance of the European Union. The contents of this training manual are those of the authors and can in no way be taken to reflect the views of the United Nations or the European Union.

5 Table of Contents List of Tables... xi List of Figures... xiii List of Annexes... xv List of Terms and Abbreviations... xvii Foreword... xx Acknowledgements... xxii 1 Integrated Pest Management Principles and Concepts Introduction Milestones in pest control Pest control vs pest management Evolution of integrated pest management Era of traditional approaches Era of pesticides Era of IPM Introduction to pest Definition Categories Definition of integrated pest management Concept of economic thresholds in IPM Economic injury level Economic threshold level Limitations of economic threshold level Concept of Agroecosystem Analysis (AESA) Basic components of AESA AESA methodology AESA by extension functionaries/farmers AESA case study - Agroecosystem Analysis methodology in vegetable Economic threshold level vs Agroecosystem analysis- based IPM Components of IPM Quarantine and regulatory Cultural Genetic - host plant resistance Physical Mechanical Biological Biotechnological Botanical Chemical iii

6 1.12 Impact of climate change on pests and their management Integration of different measures in IPM-rice case study Cultural practices Genetic management Mechanical practices Biological control practices Behavioural control Chemical control measures Advantages and disadvantages of IPM Advantages Limitations Constraints in implementation of IPM Conclusion Integrated Insect Pest Management Introduction Causes of pest outbreak Impact of chemical insecticides on insect pests Insecticide resistance Insecticide resurgence Insecticide residue Secondary pest outbreak Damage potential of insect pests Biotic and abiotic factors affecting insect pests Biotic factors host, natural enemies Abiotic factors climatic and nutritional Components of insect pest management Quarantine and regulatory provisions/factors Cultural Genetic host plant resistance Physical and mechanical Biological Chemical Conclusion Integrated Disease Management Introduction Importance of the plant disease Scope of integrated disease management History of plant disease management Era of traditional approaches Era of fungicides Era of IDM Milestones in disease management Concept of plant disease iv

7 3.4.1 Disease triangle Mode of disease transmission Direct transmission Indirect transmission Biotic and abiotic problems Parasitism and pathogenesis Disease cycle Causes and identification of plant diseases Classification of plant diseases Classification based on causes of diseases Classification based on spread and severity of infection Classification based on the part of host infected Classification based on perpetuation and dispersal of diseases Classification based on disease symptoms Symptoms of plant diseases Disease diagnostic procedures Sample collection methods Sample submission methods Diagnostic methods Plant disease management Principles of plant disease management Disease epidemiology and factors affecting spread of disease Components of IDM Quarantine and regulatory measures Cultural practices Genetic resistance Physical and mechanical measures Biological control Chemical control Constraints in IDM and future thrust Conclusion Principles and Concepts of Integrated Nematode Management in Major Crops Introduction Assessment of the situation Sampling Sampling to determine presence, absence and abundance of key species Determining host status of intended or current crops Population levels in relation to economic thresholds Avoidance of nematode problem Selection of biogeographic area Selection of planting site Selection of planting date Selection of planting stock v

8 4.4 Exclusion of problem nematodes Inspection, certification, quarantine Treatment of infected plant material Restriction of spread people, equipment, animals, water, wind Grower and public education Eradication, reduction or management Cultural practices, environmental manipulation Biological control Physical methods Chemical nematicides Fumigants Non-fumigants Systemics Conclusion Integrated Rodent Pest Management Introduction Identification of different rodent pest species Group I. Porcupine Group II. Squirrel Group III. Gerbil Group IV. Bandicoot Group V. Rat Group VI. Mice Rodent problems in different sectors Agriculture Horticulture Storage loss Integrated rodent management strategies Harbourage reduction/habitat management Rodent-proofing Mechanical control Repellants Chemical control Biological control Conclusion Integrated Weed Management Introduction Weed characteristics and classification Grasses (family-poaceae or Gramineae) Sedges (family-cyperaceae) Broad-leaves Parasitic weeds Impact of weeds on crops vi

9 6.4 Integrated weed management Preventive weed control Weed management strategies Mechanical weed control Cultural methods Biological control Chemical control Case study - Integrated weed management in vegetable crops Seed-bed management Direct-seeded and transplanted crops Conclusion Integrated Nutrient Management Introduction Soil texture and structure Importance of soil ph on nutrient availability Role of nutrients in plant health Primary or major nutrients Secondary nutrients Micronutrients Importance of soil organisms Living soils Bacteria Fungi Mycorrhizal fungi Soil protozoans Nematodes Arthropods Earthworms Soil testing Soil sampling Soil health card Soil nutrient management strategies Assessing soil health and biological activity Techniques to build soil Monitoring soil health improvement Integrated nutrient management (INM) strategies for sustainable agriculture Recycling crop residues and green manuring Role of biofertilizers in INM INM strategies for major cropping systems Conclusion Role of Pest Surveillance in IPM Introduction Survey, surveillance and forecasting vii

10 8.2.1 Pest survey Pest surveillance Pest forecasting Basic components of pest surveillance Sampling techniques and their application Types of sampling Sampling methodologies Direct sampling Indirect sampling Sampling programmes and parameters Sampling programmes Sampling parameters Designing a surveillance programme Establishment of pest surveillance system in various countries Advances in pest surveillance Conclusion Role of Biological Control Approaches in Pest Management Introduction Biological control agents Entomophages Entomopathogens Fungal antagonists Mycopathogenic bacteria Nematopathogens Biological control approaches Classical biological control Augmentation Conservation of natural enemies Mass production and use of biological control agents Mass production of host insects Mass production of rice moth, Corcyra cephalonica Rearing of Helicoverpa armigera and Spodoptera litura on artificial diet Rearing of mealy bug on pumpkin Rearing of diamond back moth (DBM) on mustard seedling Mass production of parasitoids Mass production of egg parasitoid, Trichogramma Mass production of egg-larval parasitoid, Chelonus blackburnii Mass production of larval parasitoids, Bracon hebetor/ B. brevicornis Mass production of Goniozus Mass production of predators Mass production of Chrysoperla carnea Mass production of reduviids Mass production of microbial biopesticides viii

11 Identification of important biocontrol fungi Biocontrol mechanism of fungal and bacterial bioagents Isolation of fungi and bacteria from soil, plant parts and insects Mass multiplication of fungal antagonist, Trichoderma Mass multiplication of Beauveria, Nomuraea and Metarhizium Formulation of fungal biopesticides Mass multiplication of Bacillus/Pseudomonas NPV (HaNPV and SINPV) mass production Isolation and mass production of entomopathogenic nematodes Conclusion Farmer Field School Approach in Dissemination of IPM Strategies Introduction Genesis of Farmer Field School (FFS) FFS development in the Philippines Indonesia and Farmer Field Schools Principles of FFS Fundamental elements of Farmer Field School FFS Training Methodologies and Approaches Training objectives FFS curriculum development Action plan FFS curriculum time matrix List of short studies to be conducted List of group dynamics exercises to be conducted in FFS Case study: Tentative schedule of FFS activities Conclusion Summary and Way Forward Introduction Information gaps in IPM Decision model in IPM Validation of IPM technologies Promotion of validated IPM technologies Conclusion Bibliography Annexes ix

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13 List of Tables Table 4.1 Economic thresholds for soil and root populations of plant parasitic nematodes Table 4.2 Hot water treatment for control of nematode in planting material Table 4.3 Nematicides available in world markets Table 4.4 Recommended nematicidal dosages and treatments for some important crops Table 5.1 Estimated losses caused by rodents in major agricultural crops in Asia Table 5.2 Action plan for rodent control measures in field Table 6.1 Selective herbicides for weed control in vegetable crops Table 7.1 Model soil health card for paddy Table 7.2 Model soil health card for maize Table 7.3 INM strategies for major cropping systems Table 8.1 Scale and methodology for roving pest survey in rice Table 10.1 Principles and practices of Farmer Field Schools xi

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15 List of Figures Figure 1.1 AESA observations in brinjal field Figure 1.2 AESA chart in brinjal indicating number and type of pests, defenders, P:D ratio and partly cloudy day along with the decision/conclusion Figure 1.3 Different components of integrated pest management arranged in the order of priority of use Figure 3.1 Disease triangle Figure 3.2 Disease cycle Figure 4.1 Knot/Gall formation due to root knot nematode infestation on bitter gourd roots Figure 4.2 Reniform nematode and its egg mass Figure 4.3 Cobb s decanting and sieving method for extraction of nematodes Figure 5.1 Indian crested porcupine Figure 5.2a Five-striped squirrel Figure 5.2b Three-striped squirrel Figure 5.3a Indian Gerbil, Tatera indica Figure 5.3b Burrows of T. indica Figure 5.4a Lesser bandicoot rat Figure 5.4b Burrows of lesser bandicoot rat Figure 5.5 Larger bandicoot Figure 5.6a House rat Figure 5.6b Norway rat/sewage rat Figure 5.6c Field rat Figure 5.7a House mouse Figure 5.7b Field mouse Figure 5.8 Rodent damages in field crops and storage Figure 5.9 Rodent damage in horticultural crops and poultry Figure 5.10a Tanjore kitty/trap Figure 5.10b Butta trap/palmyrah trap Figure 5.10c Multi-catch trap Figure 6.1a Grass-Cynodon dactylon Figure 6.1b Grass-Echinochloa colona Figure 6.1c Grass-Digitaria sanguinalis Figure 6.2 Sedge-Cyperus rotundus Figure 6.3a Broad leaf-celosia argentea Figure 6.3b Broad leaf-amaranthus viridis Figure 6.3c Broad leaf-eclipta alba Figure 6.3d Broad leaf-commelina bengalensis Figure 6.3e Broad leaf-monochoria vaginalis Figure 6.3f Broad leaf-ipomoea aquatic xiii

16 Figure 6.4a Parasitic weed-striga lutea Figure 6.4b Parasitic weed-cuscuta spp Figure 9.1 Mass production of egg parasitoid Trichogramma Figure 9.2a Packaging of Trichogramma cards Figure 9.2b Field release of Trichogramma eggs Figure 9.3a Life stages of Bracon hebetor Figure 9.3b Mass production of Bracon in tub method Figure 9.3c Mass production of Braconin (sandwich mehod) Figure 9.4 Mass production of green lace wing Chrysoperla carnea Figure 9.5 Mass production of predator reduviid bug Figure 9.6 Mass production of fungal antagonist Trichoderma spp Figure 9.7 Mass production of Mycopathogenic Bacteria, Pseudomonas spp Figure 9.8 White trap for EPN isolation Figure 9.9 Emergence of EPNs from infected larvae Figure 10.1 Farmer Field School process Figure 10.2 Plant compensation studies in FFS Figure 10.3 Some core topics of FFS in FFS curriculum matrix Figure 10.4 Agroecosystem analysis chart Figure 10.5 Team-building exercise (Warrior Brigade) Figure 10.6 Share of different topics in FFS curriculum Figure 11.1 Different gaps in transfer of information from laboratory to land Figure 11.2 The process of decision-making in IPM xiv

17 List of Annexes Annex 1 IPM Practices for Different Crops Annex 2 Fact sheets on Sustainable Technologies and Practices Crotalaria is Effective Against Nematode Damage of Chili in South-East Asia Integrated Pest Management for Eggplant Fruit and Shoot Borer Integrated Rice-duck Farming xv

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20 List of Terms and Abbreviations AESA DB EIL ETL FAO FFS IDM IFS INM IPM IPPC IWM LE NPPO WTO Agroecosystem Analysis Damage Boundary Economic Injury Level Economic Threshold Level Food and Agriculture Organization of the United Nations Farmer Field School Integrated Disease Management Integrated Farming Systems Integrated Nutrient Management Integrated Pest Management International Plant Protection Convention Integrated Weed Management Larval Equivalent National Plant Protection Officer World Trade Organization xviii

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22 Foreword The Centre for Alleviation of Poverty through Sustainable Agriculture (CAPSA) of the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP) has led the implementation of the SATNET Asia initiative in partnership with the Asian and Pacific Centre for Transfer of Technology (APCTT), AVRDC The World Vegetable Center, the Food Security Center of the University of Hohenheim, and the Trade and Investment Division of ESCAP, together with the active support and participation of a large number of government and civil society stakeholders. SATNET aims to contribute to improving food security and reducing poverty among the most vulnerable people in South and South-East Asia. Since its initiation in November 2011, SATNET has facilitated knowledge transfer through the development of a portfolio of technologies and best practices on sustainable agriculture and trade facilitation, and delivered a range of capacity-development programmes to network participants, including through regional and in-country workshops, high-level policy dialogues, and study tours for smallholder value-chain actors. The materials used for these capacity-development programmes are now being made available as training manuals, targeting public agricultural extension agents and researchers, project analysts in government, and technical/project staff of NGOs working in the area of extension. CAPSA is pleased to present a series of three training manuals on: 1. Integrated Pest Management 2. Post-harvest, Trade and Marketing 3. Project Development and Management for Sustainable Agriculture These manuals address areas of critical relevance for the Asia-Pacific region and have been compiled, structured and presented in a user-friendly format. The content is complemented by fact sheets on sustainable agricultural technologies and practices developed through the analytical component of the SATNET project and included in the Annex. I sincerely hope that these training manuals will be valuable learning resources in helping to strengthen national capacities to promote sustainable agriculture. We welcome feedback and suggestions from users. Sincerely, Katinka Weinberger Director, CAPSA xx

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24 Acknowledgements Many experts have contributed to the development of this training manual. CAPSA expresses its gratitude to Dr. Jeyakumar Ponnuraj for his hard work and dedication in compiling the necessary material and preparing the manual. A number of other resource persons of SATNET regional and in-country workshops organized during , including Dr. Kavya Dashora, have shared their knowledge and expertise, provided content and contributed to the review process which has made this manual possible. xxii

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26 1 Integrated Pest Management Principles and Concepts 1.1 Introduction In the 1940s, with the introduction of synthetic pesticides, the whole pest management scenario changed. The overreliance on synthetic pesticides from the late 1940s to mid- 1960s has been called the dark ages of pest control. Pest resistance to pesticides, pest resurgence and the transformation of minor into major pests due to killing of natural enemies of the pests, was observed during the 1940s. In the period immediately after the Second World War, few scientists realized that indiscriminate use of synthetic organic insecticides would create a problem. It was in the 1950s that entomologists at the University of California, United States of America (USA) developed the concept of integrated pest management (IPM) in response to the development of insecticide resistance and the destruction of insect natural enemies by insecticides. The term Integrated Pest Management was first used by Smith and van dan Bosch in 1967 and was formally recognized by the US National Academy of Sciences in The 45 years since then have seen dramatic technological changes in pest management. The IPM concept is based on the principle that it is not necessary to eliminate all pests but to reduce pest populations to levels where pests cannot cause significant loss. An integrated pest management strategy includes use of pest-resistant crop varieties, modifying agronomic practices to reduce pest incidence, biological control along with other innovative approaches to pest suppression and need-based judicious use of chemical pesticides. Rapid technological development and changing social values have also impacted pest control. The modern concept of pest management is based on ecological principles and involves the integration and synthesis of different components/control measures into a pest management system. A recent definition refers to IPM as the judicious use and integration of pest control measures in the context of the associated pest environment in ways that complement and facilitate biological and other natural pest control methods compatible with economic, public health and environmental goals. Hence, successful IPM programmes enhance agricultural profitability and protect the environment. 1.2 Milestones in pest control The history of pest control can be traced to undated reports of the use of chalk and woodash in ancient China to control pests in enclosed spaces and botanical insecticides to treat 1

27 seeds. In India, neem leaves were placed in grain bins to keep out pests. In the Middle and Near East, chrysanthemum flower powder was used as an insecticide. The first recorded application of insecticides dates back to 2500 B.C. when the Sumerians used sulfur compounds to control insects and mite pests. Subsequently, in 200 B.C. the Romans used oil sprays for pest management. Biological control methods originated as early as 300 B.C. when the Chinese used predatory ants to control citrus pests. Starting in 1930, synthetic organic compounds have been used for control of plant pathogens. Chemical pesticide use picked up with the discovery of the insecticidal properties of DDT in 1939, followed by organophosphates and synthetic pyrethroids. The evolution of integrated pest management is discussed below. 1.3 Pest control vs pest management The credit for using the term integrated control for the first time goes to Michelbacher and Bacon (1952). Subsequently, Smith and Allen (1954) stated that integrated control will utilize all the resources of ecology and give us the most permanent, satisfactory and economical insect control that is possible. Integrated control was first defined by Stern et al. (1959), as applied pest control which combines and integrates biological and chemical control. This definition stood through the late 1950s and early 1960s, but began changing in the early 1960s as the concept of pest management gained acceptance among crop protection specialists. The idea of managing insect pest populations was proposed by Geier and Clark (1961) who termed the concept protective population management, later shortened to pest management (Geier, 1966). However, in 1972 the term integrated pest management (IPM) was accepted by the scientific community after the publication of a report under the title IPM by the Council on Enironmental Quality (CEQ). Morse and Buhler (1997) summarized the differences between control and management by describing control as beating the pest into submission, using direct interventions with little knowledge of the pest population and community interaction, and usually at a local level. Management was considered a knowledge-intensive control strategy that took into account the pest complex and social issues to ensure a balanced ecosystem, using a diverse range of interventions to lower the pest population below an economic threshold over a large area. 1.4 Evolution of integrated pest management Many components of integrated pest management (IPM) were developed in the late 19th and early 20th centuries. Over the centuries, farmers developed a number of mechanical, cultural, physical and biological control measures to minimize the damage caused by phytophagous insects. Synthetic organic insecticides developed in the mid-20th century provided spectacular control of pests and led to the abandonment of traditional pest control practices. There has been increasing realization of the importance of sustainable food production through eco-friendly sustainable pest management techniques. 2

28 The history of agricultural pest control, thus, has three distinct phases. 1. Era of traditional approaches 2. Era of pesticides 3. Era of IPM Era of traditional approaches Cultural and mechanical practices like crop rotation, field sanitation, deep ploughing, flooding, collection and destruction of harmful insects/insect-infested plants, developed by farmers through experience, are among the oldest pest control methods. This was followed by the use of plant products from neem, chrysanthemum, rotenone, tobacco and several other lesser known plants in different part of the world. The Chinese were probably among the earliest to use botanical pesticides and biological pest control methods. However, systematic work on important pest control measures including resistant varieties, biological control agents and botanical and inorganic insecticides was done in the United States of America (USA) between the end of the 18th and 19th centuries. Remarkable success was achieved in the management of grape phyloxera caused by Viteus vitifoliae (Fitch) by the grafting of European grape vine scions to resistant North American rootstocks in the 1880s. Around the same time, cottony cushion scale, Icerya purchase Maskell, which was causing havoc to the citrus industry in California, USA was successfully controlled by the Vedalia beetle, Rodolia cardinalis (Mulsant) imported from Australia Era of pesticides Synthetic inorganic insecticides were broad spectrum biocides and highly toxic to all living organisms. These were followed in due course by synthetic organic insecticides like alkyl thiocyanates and lethane. The era of pesticides, however, began with the discovery of the insecticidal properties of DDT by Paul Muller in The impact of DDT on pest control is perhaps unmatched by any other synthetic substance. DDT was soon followed by a number of insecticides like HCH, chloradane, Aldrin, dieldrin, heptachlor; parathion, toxaphene, schradan, EPN (organophosphorus group) and allethrin (synthetic pyrethroid) during the 1950s and a large number of other popularly used organophosphates and carbameates. The spectacular success of these pesticides masked their limitations. The intensive and extensive use, misuse and abuse of pesticides during the ensuing decades caused widespread damage to the environment. In addition, insect pest problems in some crops increased following the continuous application of pesticides. This, in turn, further increased the consumption of pesticides resulting in the phenomenon of the pesticide treadmill (Altieiri, 1995). The combined impact of all these problems, together with the rising cost of pesticides provided the necessary feedback for limiting the use of chemical control strategy and led to the development of the IPM concept Era of IPM Although many IPM programmes were initiated in the late 1960s and early 1970s across the world, it was only in the late 1970s that IPM gained momentum. The first major IPM project in USA, commonly called the Huffaker project, spanned the period and covered 3

29 six crops, namely alfalfa, citrus, cotton, pines, pome and stone fruits, and soybean. This was followed by the large-scale IPM project called CIPM (Consortium for Integrated Pest Management) implemented between 1979 and 1985, focused on alfalfa, apple, cotton and soybean. IPM adoption for four crops was claimed to be an average of about 66 per cent over 5.76 million hectares. In 1993, the United States Government set up the National IPM Initiative and declared the implementation of IPM on 75 per cent of the nation s crop area by 2000 as a national goal. National IPM programmes were launched in several developing countries in the late 1980s and early 1990s. The most successful has been the United Nations Food and Agriculture Organization (FAO)-IPM programme for rice in South-East Asia with around 35,000 trainers exposed to IPM through this programme by the end of One of the developments in support of IPM was that the United Nations Conference on Environment and Development held in Rio de Janerio, Brazil, in 1992 assigned a central role for IPM in agriculture as part of the Agenda 21 adopted by the Conference. This led to the establishment of the IPM Facility by FAO as a coordinating, consulting, advising and promoting agency for the global advancement of IPM. 1.5 Introduction to pest Definition A loosely defined term, often overlapping with vermin, weed, plant and animal parasites and pathogens, a pest is a plant or animal detrimental to humans or human concerns (as agriculture or livestock production). Alternative meanings include troublesome organisms that cause epidemic disease associated with high mortality, specifically, plague. The FAO defines a pest as any species, strain or biotype of plant, animal, or pathogenic agent, injurious to plants or plant products. It is possible for an organism to be a pest in one setting but beneficial, domesticated or acceptable in another Categories Pests are categorized as key, major, minor, sporadic and potential pests based on population and capacity for causing damage. These terms are used rather loosely. Key pests: These cause the most damage, posing a persistent and perennial threat to crops and not controlled with available technology. Cotton bollworms, diamond back moth, chickpea pod borer, sugarcane borers and some vectors are common key pests. Major pests: These require repeated control, but economic damage can be avoided by timely intervention. Important sucking pests such as cotton jassid and whitefly, brown planthopper and leafhopper on rice, sugarcane whitefly and scale insect, fall in this category. Rice stem borer, gall midge and leaf folder are also major pests. Minor pests: These are easily amenable to available control measures and a single pesticide application is generally enough. Cotton strainers, grey weevil, thrips and mites, rice hispa and root weevil, sugarcane mealybugs, thrips and mites, and Spodoptera litura (Fabricius) on oilseed and vegetable crops are minor pests. 4

30 Sporadic pests: The population of these pests is usually negligible but in favourable environmental conditions, can take a virtual epidemic form, requiring suitable management strategies. These are highly sensitive to abiotic conditions and once the favourable conditions end, only a residual population survives. Many sporadic pests like white grubs, hairy caterpillars, cutworm and grasshoppers are polyphagous. But some oligophagous pests such as sugarcane pyrilla may also be sporadic in nature. Potential pests: These presently do not cause economic damage and, therefore, should not be labelled pests. Any change in the ecosystem, for instance relating to cropping pattern or cultural practices, and indiscriminate use of chemical pesticides against other pests, may cause the potential pests to become serious pests. 1.6 Definition of integrated pest management Since integrated control was first defined by Stern et al. (1959), more than 65 definitions of integrated control, pest management or integrated pest management have been proposed. A broader definition adopted by the FAO Panel of Experts (FAO, 1967) states: Integrated pest control is a pest management system that, in the context of associated environment and population dynamics of the pest species, utilizes all suitable techniques and methods in as compatible a manner as possible and maintains pest populations at levels below those causing economic injury. According to the National Academy of Sciences, IPM refers to an ecological approach to pest management that consolidates all available necessary techniques in a unified programme to manage pest populations in order to avoid economic damage and minimize adverse side effects (NAS, 1969). Smith (1976) defined IPM as a multidisciplinary ecological approach to the management of pest populations, which utilizes a variety of control tactics compatibly in a single coordinated pest management system. In its operation, integrated pest control is a multitactical approach that encourages the fullest use of natural mortality factors, complemented when necessary by artificial pest management. IPM is also defined as the intelligent selection and use of pest control measures that will ensure favourable economical, ecological and sociological consequences: Selection, integration, and implementation of pest control based on predicted economic, ecological, and sociological consequences. A comprehensive approach to pest control that uses combined means to reduce the status of pests to tolerable levels while maintaining a quality environment. A sustainable approach to manage pests is by combining biological, cultural, physical and chemical tools in a way that minimizes economic, health and environmental risks. 5

31 1.7 Concept of economic thresholds in IPM Economic injury level Insect colonization and feeding often cause injury to plants. The injury does not necessarily result in damage. The latter refers to a measurable loss of host ability, most often including yield quantity, quality or aesthetics. The lowest level of injury where damage can be measured is called the damage boundary (DB), while the lowest number of insects that will cause economic damage is referred to as the economic injury level (EIL), which can be worked out as follows: EIL = C/VID EIL = No. of injury equivalents per production unit (insects/ha) C = Cost of management activity per unit of production (per ha) V = Market value per unit of product (per ton) I = Crop injury per pest density D = Damage per unit injury (ton reduction/ha) Economic threshold level Economic threshold level (ETL) is the best known and most widely used index in making pest management decisions. It is defined as the population density at which control measures should be initiated against an increasing pest population to prevent economic damage. Although expressed in insect numbers, ETL is, in fact, a time parameter, with pest numbers being used as an index for determining when to implement management strategies. As with the EIL, the ETL can also be expressed as an insect equivalent. In economic terms, ETL is defined as the level to which a pest population should be reduced to reach the point where marginal revenue just exceeds marginal costs. ETL is fixed arbitrarily at around 75 or 90 per cent of EIL, so that necessary control measures are initiated at this level to contain the pest population reaching EIL Limitations of economic threshold level The terms EIL and ETL are themselves misleading because both are defined in terms of population densities, while the former represents an injury level and the latter the right time for implementation of control measures. This limitation may be overcome by defining these levels in terms of injury equivalents. There is no rigorous definition of economic damage (the amount of injury that will justify the cost of control). Because economic damage was not described mathematically in terms of its components, it could not be assessed solely on the basis of definition by Stern et al. (1959). Decision levels for management of some types of pest cannot be determined with EILs. Besides medical and veterinary pests, it includes most vectors. It is very difficult to monetize the reduction in aesthetic value caused by a given injury. A similar problem is also encountered when assessing damage caused by forest pests. Almost all EIL components are difficult to estimate for pests; determining accurate market values is a problem; management costs may vary greatly and frequently include only environmental and social costs, and the injury/crop-response relationship may be difficult to determine. 6

32 The concept is unsuitable in the case of a multiple pest attack on a single crop at the same stage. However, in spite of these limitations, the EIL and ETL concept offers a practical approach to pest-related decision-making. 1.8 Concept of Agroecosystem Analysis (AESA) Globally IPM underwent several changes over the years in its focus and approaches, namely damage threshold, EIL, ETL and currently standardized as AESA-based IPM, which has gained universal acceptance. In 2002, FAO defined IPM as the careful consideration of all available pest control techniques and the subsequent integration of measures that discourage development of pest populations and keep pesticides and other interventions to levels acceptable from an economic, environmental and public health perspective. IPM emphasizes healthy crop growth with the least possible disruption to agroecosystems and encourages natural pest control mechanisms. AESA-based IPM is being promoted by FAO. The AESA approach can be gainfully used by extension functionaries and farmers to analyse field situations with regard to pests, defenders, soil conditions, plant health and climatic factors, and their interrelationship for a healthy crop. A critical field analysis will help in taking appropriate decisions on pest management practices Basic components of AESA i. Plant health at different stages ii. Built-in compensation abilities of the plant iii. Pest and defender population dynamics iv. Soil conditions v. Climatic factors vi. Farmers experience AESA methodology Field observation i. Enter the field at least 1.5 m away from the bund. Select a 1 m 2 area at random. ii. Record visual obervations in the following sequence: a. Flying insects (both pests & defenders) b. Close observation of pests and defenders on plants. c. Observe pests like borer and BPH and defenders like cooccinellid, chrysopa, ground beetle/rove beetle and earwigs, by scraping the soil surface around the plants. d. Record disease and its intensity. e. Record insect damage and disease incidence as percentage. iii. Record parameters like number of leaves, plant height and reproductive parts of selected plants for making observation in the ensuing weeks. Observe nematode damage symptoms. iv. Record types of weeds, their size and population density in relation to crop plant. v. Record soil conditions, namely flooded, wet or dry. vi. Observe rodent live burrows. 7

33 vii. Record climatic factors, namely sunny, partially sunny, cloudy or rainy for the preceding week. Drawing Make a chart, with a drawing of the plant in its centre, pests on left side and defenders on the right side of the plant. Indicate the soil condition, weed population, rodent damage, among others. Use natural colours, for instance, green for a healthy plant and yellow for a diseased plant or leaves. Care should be taken to place the pests and defenders on the part of the plant where they were observed. The common name of the pest should be indicated on the diagram. Weather conditions should be depicted appropriately, for example by the figure of a sun just above the plant to indicate sunny conditions. Cloulds indicate cloudy conditions while a sun half-masked by clouds, indicates partially sunny conditions. Group discussion and decision-making The observations depicted in the previous and current charts should be discussed by the farmers with questions related to changes in pest and defender populations in relation to crop stages and soil and weather conditions. The group may evolve a strategy based upon weekly AESA observation and corresponding changes in the pestdefender ratio (P:D) and decide on appropriate pest management practices. Strategy for decision-making Some defenders like lady bird beetles, ground beetles, rove beetles and wasps play an important role in determining the P:D ratio AESA by extension functionaries/farmers During their regular village visits, extension functionaries mobilize farmers, conduct an AESA and critically analyse factors such as the pest population vis-á-vis the defender population and their role in natural pest suppression, the influence of weather and conditions on the likely build-up of the defender/pest population. They may also decide on the basis of the AESA, which uses IPM components like release of defenders, application of neem formulations and other safe pesticides for specific pest situations. This exercise can be repeated by extension functionaries during every village visit to motivate farmers to adopt AESA. Following a brief exposure to AESA during IPM demonstrations/field training, farmers can implement it on their field. Trained farmers can train fellow farmers, thereby making a large group of farmers proficient in conducting a weekly AESA and deciding on action suited to specific pest situations. A farmer-to-farmer training approach will go a long way in promoting IPM across a large area on a sustainable basis. 1.9 AESA case study - Agroecosystem Analysis methodology in vegetable Agroecosystem analysis helps farmers understand their crop and make appropriate pest management decisions. Ideally, the weekly field school session should start with an Ecosystem Analysis by subgroups, followed by group discussions. This would enable 8

34 farmers to follow the developments in the ecosystem and take pest management decisions on a weekly basis. AESA in vegetables (brinjal) can be conducted for all three stages of the crop every week Nursery stage: - Observe all nursery beds for insect pests and disease. Vegetative stage: - Observe 20 plants and scan the entire plant for pests and bioagents. - for sucking pests, the top two leaves, middle two leaves and bottom leaf are observed. Flower and fruiting stage: - Observe 20 plants and scan the entire plant for live insect pest attack on flower buds, flower and fruit damage and healthy pests, and available bioagents (all live ones). - for sucking pests, the top two leaves, middle two leaves and bottom leaf are observed. Activities: 1. Farmers form groups of four to five each. Some groups take the Farmers Practice field and other groups take the IPM field. 2. Each group selects 20 sample plants across the diagonal of the field. To select a plant, walk across the diagonal of the field and choose a plant at every 5 m. In large fields increase the distance between selected plants. 3. Select three leaves from the plant, one from the top, one from the middle and one from the bottom. Pick or turn the leaf and count the number of jassids, whitefly adults and nymphs, and aphids (ignore other sucking pests if not common). 4. Systematically check all leaves and the stem for any predators (moving downward from the top leaf). 5. Count the total number of fruiting parts. 6. Open the bracts of each individual fruiting part and record: Number of fruiting parts with fruit damage Number of fruit borer larvae Any predators 7. Check the ground under the plant and record any predators. 8. Collect the predators in plastic vials to show to other groups. 9. Uproot one brinjal plant for drawing. 10. After 20 plant observations are noted, find a place for the group to sit and make colour drawings on a large piece of paper. Draw the plant with the correct number of branches. Draw the sun and indicate with clouds if it is cloudy. Shedding buds are coloured yellow. Draw the pests on the right hand side of the cotton plant as follows: Sucking pests: Indicate total number found (top two leaves, middle two leaves and bottom one leaf) Indicate the total number of leaves checked (50) (- calculate the average per leaf) Fruit borer larvae: Indicate total number of fruiting parts checked Indicate total number of fruiting parts with fruit borer damage (- calculate percentage of damaged fruiting parts) 9

35 On the left hand side of the plant, make a drawing of the predators found. Again, indicate total numbers found (and calculate the average per plant). If a lot of weeds are noted, draw weeds next to the vegetable plant. Indicate the intensity of disease incidence, rodent damage, among others. 11. After the drawing excercise, the following questions are discussed. a. Describe the general condition of the plant. b. What do farmers think to be the most important factors affecting their crops at this stage? c. What, if any, measure should be taken? 12. When all groups have finalized their drawings and answered the questions, they present their work to each other, explaining the sampling and drawings and discuss the answers to the three questions. 13. One group presents its results for each treatment. 14. Each week, a different group member makes the presentation. In Farmer Field Schools, the ecosystem analysis drawings of preceding weeks should be available for comparison and a discussion of the development of the crop and insect populations. It is easy to forget what the field looked like earlier in the season, what insect populations were found and when control measures were taken. Figure 1.1 AESA observations in brinjal field 10

36 Figure 1.2 AESA chart in brinjal indicating number and type of pests, defenders, P:D ratio and partly cloudy day along with the decision/conclusion 1.10 Economic threshold level vs Agroecosystem Analysisbased IPM The ETL approach takes only the pest population into account, but farmers have to base decisions on a larger range of observations when using the Agroecosystem Analysis. Unfortunately, the ETL approach is still being recommended as an IPM method. But there are many reasons for not using an ETL approach, one being that it is based on parameters that change all the time and are often not known. An ETL is calculated from: 1. the management cost per hectare 2. the price of the farm produce per kilogram 3. expected damage or yield loss (kilogram/pest) While management cost can be estimated, it is usually not possible to know the produce price per kilogram when the crop is still growing. Damage caused by a certain density of insects cannot be predicted at all as it depends on many other factors, such as crop variety, weather conditions, water and nutrient availability and the stage of the plant. It also depends on the presence and performance of natural enemies. There is a big difference between a bean plant with 20 aphids and a bean plant with 20 aphids and 1 hover fly larva. This is why the ETL that is recommended in manuals for farmers can never be applied in a farmer s field. Farmers cannot base decisions on only a simple pest count but have to consider many other aspects such as crop ecology, growth stage, natural enemies and weather condition as well as their economic and social situation. Another important consideration is that good crop management does not only depend on pest control, but even more on the prevention of pests. IPM specialists have realized the limitations of the ETL and gradually developed the AESA as a more flexible tool for crop management decisions. 11

37 AESA considers: the crop growth stage weather conditions crop development factors (including plant compensation ability) type and number of insect pests type and extent of disease type and number of natural enemies type and amount of natural disease control agents (if applicable) type and amount of weeds water availability (irrigation, drainage) soil fertility status fertilizer application field activities since the preceding week other observations and farmers experience 1.11 Components of IPM IPM has a variety of components under different frameworks and emphasizes the intelligent selection and use of the optimum pest management strategy. The selected pest management option should be effective, practical, economical and environmentally sound. Selecting a suitable strategy requires understanding of the pest life cycle and behaviour, deciding whether the infestation has economic consequence or not, comparing different pest management options and then implementing the suitable IPM option Quarantine and regulatory This process involves government regulatory rules banning the entry of seeds and infested plant material into the country or their movement from one part of the country to another. These are known as quarantine methods and are of two types, namely domestic and foreign quarantine Cultural Cultural methods of pest control include regular farm operations that either destroy pests or prevent economic loss from pests. Cultural practices such as crops/varieties to be grown, time and manner of planting, tillage, field and crop sanitation, fertilizer application and irrigation, harvesting time and procedure, and even off-season operations in cropped fields are among pest management aids Genetic - host plant resistance This involves selection of crop varieties relatively resistant or tolerant to pests and with reasonably high yields. The use of insect-resistant crop varieties is economically, ecologically and environmentally advantageous. 12

38 Physical This method aims to reduce pest populations by using devices which affect pests physically or alter their physical environment. Hot or cold treatment: Application of dry heat including exposure to sun during the hot summer April-June period helps kill a number of pests in seeds and stored commodities. Cold storage of fresh and dry fruits and vegetables is often used to avoid fruit fly, potato tuber moth and pathogen damage. Maintaining a temperature of 10 C for several days kills fruit fly maggots. Moisture: Insects are highly sensitive to a reduction in air moisture content but humidity manipulation is generally not feasible in field conditions. Light traps: Light traps for attracting and mass-killing several species of moths and beetles were used as a control measure before the advent of synthetic organic insecticides. The traps can still be useful for monitoring the population of important insect pests Mechanical The reduction or suppression of insect populations by means of manual devices is covered under mechanical control methods. Hand picking: The ancient technique of hand-picking and destroying large-sized, conspicuous, immature or mature stages of insects can be effective under certain conditions. The collection and destruction of egg masses of top borer in the first and second brood during March and May in ratoon and autumn planted crops, if done over a compact block, can reduce top borer damage in endemic pockets. Exclusion by screens and barriers: Trenches of cm depth or erecting 30 cm-high tin-sheet barriers around the field, can protect the crop from moving bands of locusts and hairy caterpillars. Trapping and suction devices: Several types of mechanical devices are used for collecting insect pests. Insects are trapped in cages using suitable bait. Clipping, pruning and crushing: Pruning and destruction of infested shoots and floral parts is effective in checking the multiplication of scales, mealy bugs and attack of gall midges on fruit trees Biological The term biological control was first used by Smith in 1919 to signify the use of natural enemies to control insect pests. Natural control: The maintenance of pest populations within certain upper and lower limits by abiotic and biotic factors as well as the characteristics of the species under consideration is called natural control. 13

39 Parasitoid: A parasitoid is an organism which is usually much smaller than its host. It kills its host and requires only one host for development into a free-living adult. Braconid wasps are good examples of parasitoids. Predator: A predator is a free-living organism throughout its life, is usually larger than its prey and requires more than one prey to complete its development. Lace wings, lady bird beetles and preying mantids are good examples of predators. Pathogens: Three approaches have been used for exploiting microorganisms for pest control. Colonization: This approach, often referred to as introduction or establishment, includes introduction of the microorganism into the pest population, where it maintains and spreads itself. Periodic reintroduction of the pathogen into the pest population is referred to as seasonal colonization. Conservation: This approach, often referred to as environmental augmentation, refers to the enhancement in the efficiency of naturally occurring pathogens by manipulating cultural practices or other environmental conditions. Microbial insecticides: This approach, also referred to as inundative augmentation, involves dissemination of microorganisms in the pest population in large quantities in a manner similar to the application of insecticides. Baculovirus, Bacillus thuringiensis, Beauveria, and Rhabditis are used as microbial pesticides Biotechnological Three components of modern plant biotechnology have been recognized, namely: - recombinant DNA technology - monoclonal antibody production - cell and tissue culture A combination of these three processes provides the basis of genetic engineering. The utility of plant biotechnology in crop improvement has increased. Wide hybridization has been successfully used to transfer genes from one species or genus to another by conventional breeding techniques. Wild species are potential sources of genes for resistance to several types of biotic and abiotic stress. Grassy stunt virus resistances genes from Oryza nivara, brown planthopper and whitebacked planthopper resistance from O. officinalis have been successfully transferred in rice Botanical As many as 2,121 plant species have been reported having pest control properties. However, for development into an ideal botanical insecticide, in addition to high insecticidal activity, plant species must also possess other characteristics including: - be safe to plant and animal life - biodegradability with sufficient residual action 14

40 - economical isolation procedures for active component(s) - yield products of consistant quality Examples of botanical insecticides include neem, China berry, tobacco, pongram and custard apple Chemical Pesticides are widely used in agriculture to control pests such as insects, rodents, weeds, bacteria, fungus, etc. Chemical tactics to manage pests can include many types of compounds. Some merely repel or confuse pests while others interfere with weed photosynthesis, insect moulting processes or development. Yet others, including some botanical and most conventional insecticides, are broadly toxic to living systems. The term pesticide literally means pest killer. The specific type of organism killed is revealed in the name; i.e. insecticides kill insects, herbicides/weedicides kill weeds, fungicides kill fungi, rodenticides kill rodents and so on. Keeping in view the ill effects of chemical pesticides such as development of pest resistance to commonly used pesticides, pest resurgence, outbreak of secondary pests, pesticide residues in food, fodder, soil, air and water resulting in human health hazards and ecological imbalances, they should be used judiciously as a last resort in IPM. Figure 1.3 Different components of integrated pest management arranged in the order of priority of use 1.12 Impact of climate change on pests and their management As poikilothermic organisms, insects are highly sensitive to temperature. Increased temperature is likely to result in the need for increased insecticide application because of the likelihood of the presence of additional pest species, more generations of pests per growing season and the earlier arrival of migratory pests. It has been shown that pyrethroid 15

41 insecticides and spinosad are not as effective in killing insects at higher temperatures. Similarly, biology and life cycles of several arthropods will keep altering with climate and this could ultimately affect successful pest management practices such as cultural, biological and chemical control. The exact impact of climate change on insects and pathogens is uncertain. However, as climate change is a gradual process, this will provide opportunities to modify agricultural practices. Basics IPM practices such as field monitoring, pest forecasting, record keeping, and choosing economically and environmentally sound control measures would help in dealing with the effects of climate change Integration of different measures in IPM-rice case study Cultural practices a. Raise green manure crop Sesbania or sunhemp and incorporate 45-day-old crop in soil during land preparation wherever possible. b. Select suitable pest resistant or moderately resistant variety. c. Use disease and insect-free pure seed. d. Seed treatment for diseases with carbendazim 50 per cent 2 g/kg seed or 5-10 g/kg of seed for seed or soil-borne diseases and carbosulfan 2 g/kg of seed for root nematodes. e. Timely planting/sowing. f. Pre-sowing irrigation: Many weeds can be controlled by pre-sowing irrigation of area where nursery or seedlings are to be transplanted. Weeds that emerge can be ploughed under. g. Raising healthy nursery. h. As far as possible, rice seedling should be free from weed seedlings at the time of transplanting. i. Destruction of the left-over nursery, removal of weeds from field and cleaning of bunds. j. Normal spacing with hills/m 2 depending on the duration of the variety. k. 30-cm alley formations at every m distance in plant hopper and sheath blight endemic areas. l. Balanced use of fertilizer and micronutrients as per local recommendations. Proper water management, alternately wetting and drying to avoid water stagnation, in plant hopper, bacterial blight and stem rot endemic areas. Maintain thin water layer on soil surface to minimize weed growth. m. For direct sown rice, crop should be sown in lines at recommended spacing to facilitate inter-weeding. Mechanical weeding methods should be used after 2-3 weeks and again if necessary after 4-6 weeks of sowing. n. Harvest close to ground level to destroy insect pests present in internodes/stubbles. This will also expose insects to birds, which help in natural biocontrol of insect pests. o. After harvest, the field should be thoroughly flooded with water and ploughed with discs or rotators to kill hibernating larvae of stem borer present in stubbles. Summer ploughing also exposes larvae and pupae of rice swarming or ear cutting caterpillar (climbing cutworm) hidden in the soil to birds and weather. 16

42 Genetic management Insect pest and disease-resistant/tolerant varieties for key/major pests in the area are selected for sowing. This will lower expenditure on other pest management options Mechanical practices Collection of egg masses and pest larvae placed in bamboo cages for conservation of biocontrol agents. Removal and burning of diseased/pest-infested plant parts. Clipping rice seedling tip at the time of transplanting to minimize carry-over of rice hispa, case worm and stem borer infestation from seed bed to the transplanted fields. Use of coir rope in rice crop for dislodging case worm, cut worm and swarming caterpillar, leaf folder larvae, etc. on to water broadcast with 1 l kerosene in 25 kg soil/ha) Biological control practices Trichogramma japonicum and T. chilonis may be 0.1 million/ha on appearance of egg masses/moth of yellow stem borer and leaf folder in the field. Natural biocontrol agents such as spiders, drynids, water bugs, mirid bugs, damsel flies, dragonflies, meadow grasshoppers, staphylinid beetles, carabids, coccinellids, Apanteles, Tetrastichus, Telenomus, Trichogramma and Bracon, Platygaster should be conserved. Egg masses of borers collected and placed in a bamboo cage-cum-percher till flowering to permit the escape of egg parasites and trap and kill hatching larvae. Predatory birds would also perch on these. Habitat management: Protection of natural habitats within farm boundary may help in conserving natural pest enemies. Planting of flowering weeds like marigold and sun hemp on farmland and rice bunds increases the beneficial natural enemy population and also reduces the incidence of root knot nematodes. Straw bundles offer refuge to spiders and provide a perch for birds. Pest-defender ratio (P:D) 2:1 may be used to avoid application of pesticides against plant hoppers Behavioural control Mass trapping of yellow stem borer male moths by installing pheromone traps/ha with lures containing mg pheromone, 20 days after transplanting Chemical control measures Detailed chemical control measures against insect pests and diseases are given in the Generic IPM module based on the vegetative stage. Chemicals should be used as the last choice only after the pest population cross ETL. 17

43 1.14 Advantages and disadvantages of IPM Advantages Decreased chemical application reduces health risks for farm workers/farmers/ consumers. Decreased chemical application reduces risk of deterioration and disfigurement of holdings. Decreased chemical application may result in financial savings. Environmental improvements in the facility to implement IPM will enhance long-term stability of the holding over and above the protection against pests. IPM may be the only solution to some long-term pest problems where chemical application is not effective. IPM ultimately allows institutions to have greater control over and knowledge of pest activity. IPM is the pest management technique of choice for major institutions Limitations Requires more staff time than traditional pest management, even if implementation is contracted to a pest management company. Requires coordinated effort by all staff members. May initially be more expensive Constraints in implementation of IPM The Consultant Group of the IPM Task Force has conducted an in-depth study of constraints to the implementation of IPM in developing countries, which can be categorized into the following five main groups. a. Institutional constraints: IPM requires an interdisciplinary, multifunctional approach to solving pest problems. The traditional top-down research, in many cases does not address the real needs of farmers who are the end users and either adopt or reject the technology based on its appropriateness. Institutional barriers to national research scientists conducting on-farm research in developing countries are real, and need to be addressed. b. Information constraints: The lack of IPM information that can be used by farmers and extension workers is a major constraint as is the lack of training material, curricula and experienced IPM teachers. In many cases, field-level extension workers are not sufficiently trained in IPM to instil confidence in farmers. c. Sociological constraints: Often farmers and farm-level extension workers become conditioned to advocate the use of chemicals as being simple and highly effective. This is a major constraint in IPM implementation. Private industry and public sector extension agencies need to complement each other s efforts to overcome this constraint. d. Economic constraints: Funding for research, extension and farmer training on IPM is also a major constraint. e. Political constraints: In some cases, government pesticide subsidies and their linkage with government-provided credit for crop production are important constraints to farmers acceptance of IPM. 18

44 1.16 Conclusion IPM reduces emphasis on pesticide use by promoting cultural, biological, genetic, physical, regulatory and mechanical pest controls. A good IPM programme requires planning, monitoring and evaluation. Effective IPM programmes must address the following key issues: Changing farmers perception that chemical pesticides are easy to apply and effective and IPM is difficult to adopt and ineffective. Informing pesticide industry representatives about the advantages of IPM and the ill effects of pesticides. Creating awareness and participation of government agricultural extension functionaries. Promotion of only safe chemicals and avoiding use of broad-spectrum chemicals. Ensuring timely availability of quality biocontrol agents including biopesticides. 19

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46 2 Integrated Insect Pest Management 2.1 Introduction Integrated Insect Pest Management can be defined or understood in various ways including: Selection, integration, and implementation of pest control based on predicted economic, ecological, and sociological consequences. A comprehensive approach to insect pest control that uses combined means to reduce the status of pests to tolerable pest levels while maintaining a quality environment. Insect pest management measures are either preventive or therapeutic. Preventive practices lower environmental carrying capacity by reducing the general equilibrium position or increasing host tolerance to pest injury. Prevention relies on an intimate understanding of the pest life cycle, behaviour and ecology. Therapeutic measures are applied as a correction to the system. The objective of therapy is to dampen the pest population below the economic injury level. Actual integration involves the proper choice of compatible measures and blending these so that each component potentiates or complements the other. 2.2 Causes of pest outbreak Human activity disturbing the biotic balance of an ecosystem is the prime cause for a pest outbreak. Some examples are listed below: i. Deforestation for agricultural cultivation, forcing pests earlier feeding on trees to feed on crops. ii. Destruction of natural enemies by excessive or indiscriminate use of insecticides. iii. Intensive and extensive cultivation such as monoculture leads to multiplication of pests. Extensive cultivation over a large area increases the pest outbreak as there is no competition for food, increasing the multiplication of insect pests (e.g. stem borers in rice and sugarcane). iv. Introduction of new varieties and crops Fields planted with modern crop varieties, which are short and heavy-tillering, develop a distinctly different microclimate conducive for the proliferation of insect pests. Varieties with favourable physiological and morphological factors cause multiplication of insects (e.g. succulent dwarf rice varieties favour leaf folder, Combodia cotton favours stem weevil and spotted bollworm, hybrid sorghum and pearl millet favour shoot flies and gall midges). v. Improved agronomic practices including cultural practices, excessive use of fertlizers and pesticides, and improved irrigation facilities lead to intensive cropping systems 21

47 which may cause pest outbreak (e.g. increased use of nitrogenous fertilizer leads to high leaf folder incidence in rice, closer planting leads to Brown Plant Hopper and leaf folder increases in rice). Granular insecticides produce phytotonic effect on rice which may also be a reason. vi. Introduction of a new pest in a new environment due to a variety of factors, including absence of natural enemies in an area where the crop was not cultivated previously, the pest multiplies rapidly. vii. Accidental entry of pests from foreign countries through air/sea ports - The implementation of the General Agreement on Trade and Tariffs has made the international movement of plant products and planting material easy. Moreover, international passengers may also carry material that should be quarantined, without being aware of it. 2.3 Impact of chemical insecticides on insect pests Insecticide resistance Resistance is the development of the ability in the insect to tolerate an insecticide dose, which would be lethal to the majority of pests in a normal population of the same species. The first documented case of resistance to insecticides appeared in 1914 when the San Jose scale became resistant to hydrogen cyanide Insecticide resurgence Resurgence refers to an abnormal increase in the pest population or damage following insecticide application, often far exceeding the economic injury level. The main cause of resurgence is mortality of natural enemies Insecticide residue Only a small amount of the pesticide (<1 per cent) applied to the crop reaches target pests and the remaining (>99 per cent) contaminates soil, water, air, food, feed and forage. Nearly all of the human population has traces of pesticides like DDT and HCH Secondary pest outbreak The use of broad-spectrum insecticides kills a large numbers of insects besides the target pests. This reduces competitive pressure between species, increases their numbers and turns harmless insects into pests. Thus, the use of synthetic pyrethroids against bollworms in cotton, kills natural enemies of the minor pest whitefly. 2.4 Damage potential of insect pests Reducing pest-associated crop losses, estimated at 14 per cent of total agricultural production, is essential to meet the increasing demand for food crops. However, nearly 30 to 50 per cent of the actual crop production is lost due to insect damage. The emerging problems of insecticide resistance, secondary pest outbreak and resurgence, add to the cost of plant protection. Several insect pests are difficult to control even with insecticides and are causing widespread damage across seasons and geographic regions. 22

48 The introduction of high yielding varieties (HYVs), increased fertilizer use and irrigation, changes in crops and cropping patterns, and indiscriminate use of pesticides have changed the pest spectrum and pest control measures. Until the 1950s, insect pests were not a major concern for crop production. However, even at that time, a number of insect pests were known to cause serious crop damage. Thus, in the 1950s, fruit, cotton, rice and sugarcane yields fell by 25, 18, 10 and 10 per cent, respectively due to insect pests. The losses in other crops by insect pests were quite low. The introduction of HYVs, together with the increasing use of agrochemicals, boosted farm productivity with a concomitant increase in pest loss. Very little information is available on the extent of losses due to insect pests in different crops in India and other developing Asian countries. Crop losses caused by insect pests, disease and weeds have increased from 34.9 to 42.1 per cent over the past 50 years, despite intensified pest control measures. There are additional costs in the form of pesticides applied for pest control, valued at $10 billion annually. 2.5 Biotic and abiotic factors affecting insect pests Pest populations tend to fluctuate as a result of inherent characteristics influenced by environmental factors. Environmental factors favouring fecundity or speed of development and not inimical to survival, result in increased populations while those with a reverse effect, cause a decline in numbers. Environmental factors may be classified as abiotic and biotic. Among the former, it is primarily physical factors such as temperature, moisture and light that have a direct influence on insect pest populations. These factors also influence pest populations indirectly by modifying biotic factors. Biotic factors include food and other populations, primarily natural enemies Biotic factors host, natural enemies Vital processes such as growth, nutrition and reproduction depend upon the interaction between individuals of the same species or between those of different species. The important biotic components affecting insect pests, are natural enemies and food. Natural enemies: Predators, parasites/parasitoids and disease-causing microorganisms such as fungi, bacteria, viruses and rickettsiae. The size of the predator population influences the size of their prey population in field conditions. Similarly, the size of population of parasitoids and entomopathogenic microorganisms can regulate insect pest populations. Food/host: The quantity and quality of food play an important role in insect survival, growth, reproduction and distribution Abiotic factors climatic and nutritional Climatic factors have a dominating influence on the development, longevity, reproduction and fecundity of insect pests. It is well known that pest population densities fluctuate with prevailing weather conditions such as temperature, moisture, light and wind. Extremes of temperature, humidity or rainfall cause mortality among pests and natural enemies. Temperature: There is a fairly well-defined favourable temperature range for every insect species known as the preferred temperature or temperature preferendum. Exposure to temperatures outside the favourable range may retard insect growth and development or even cause its death. 23

49 Moisture: A constant moisture supply is essential for metabolic reactions as well as for salt dissolution and transport. Thus, moisture plays an essential role in the management of insect pests. Light: Light acts as a token stimulus by enabling insects to regulate and synchronize life cycles with seasonal changes. Unlike temperature, light is a non-lethal factor and flows in a specific direction which orientates insects to the source of light, a behaviour pattern which can be exploited by setting up a light trap. Oxygen and carbon dioxide: Some insects can survive several days without oxygen by reducing metabolic rates and utilizing oxygen in their tissues. Some insects can live in an atmosphere with high carbon dioxide content for several days. However, an excess of this gas in the atmosphere retards growth of many insects. Water currents: Water currents often determine which species of insects inhabit a particular area. Edaphic factors: Edaphic factors include the structure, texture and composition of soil along with its physical and chemical characteristics. As many of the lepidopteran pests pupate in soil, edaphic factors may have an impact on insect pests. 2.6 Components of insect pest management Quarantine and regulatory provisions/factors As a result of the increased liberalization of agricultural trade, the chances of accidental introduction of exotic pests are very high. The quarantine and regulatory control aspects of IPM ensure that pests are not introduced along with planting material. Quarantine laws have been enacted in many countries Cultural Cultural methods of pest control include farm operations which either destroy pests or prevent economic loss caused by pests. Such cultural practices include: Preparation of pest-free nurseries or main fields by removing plant debris, trimming of bunds, soil treatment and deep summer ploughing, which kills various stages of pests. Proper field drainage is important. Soil testing for nutrient deficiencies to determine which fertilizer should be applied. Selection of clean and certified seeds and seed treatment with fungicide or biopesticides before sowing. Selection of seeds of relatively pest-resistant/tolerant varieties has a significant role in pest suppression. Adjusting sowing and harvesting time to avoid the peak pest season. Rotation of crops with non-host crops helps reduce the incidence of soil-borne disease. Proper plant spacing makes plants healthier and less susceptible to pests. Optimum use of fertilizer FYM and biofertilizer. Alternate wetting and drying to avoid water stagnation because high soil moisture levels for a prolonged period are conducive for pest development, especially soil-borne disease. Proper weed management as most weeds not only compete with crop for micronutrients, but also harbour pests. Placing pan sticky traps for whiteflies and aphids above canopy height. 24

50 Synchronized sowing. A community approach is required for simultaneous sowing over a vast area so that the pest does not get to the crops at different stages of growth for population build-up. If pests appear in abundance, control operations could also be used. Growing trap crops on field borders. Pests prefer certain crops which are known as trap crops. Planting such crops on the border of the fields, leads to the growth of pest populations on these crops. The pests can then be easily targeted with pesticides or natural enemies. Root dip or seedling treatment in pest-infested area. Inter-cropping or multiple cropping, wherever possible. All crops are not preferred by a pest species and certain crops act as repellents, keeping pests away from preferred crops. Harvesting as close as possible to ground level. This is because some developmental stages of insect pests/diseases remain on plant parts which act as primary inoculum for the next crop season. Hence, harvesting crops close to ground level lessens the incidence of pests in the next season. Removal and destruction of crowded/dead/broken/infested branches while pruning fruit trees. These should not be piled in the orchard as this may act as source of pest infestation. Large pruning wounds should be covered with Bordeaux paste/paint to protect the plant from pest/disease Genetic host plant resistance Selection of comparatively more pest-resistant/tolerant varieties with reasonable yield levels reduces the inoculum of the pest. Host plant resistance forms the central point of IPM on which other methods are superimposed. Several resistant varieties in different crops have been evolved against pests by using breeding/biotechnological methods. Resistance is compatible with all other methods of pest control Physical and mechanical Removal and destruction of egg masses, larvae, pupae and adults of insect pests and infested parts of plants, wherever possible. Installation of bamboo cage-cum-bird perches in the field and placing parasitized egg masses inside for conservation of natural enemies and withholding of pest species, wherever possible. Use of light traps and destruction of trapped insects. Use of rope for dislodging leaf feeding larvae (e.g. caseworm and leaf folders). Installation of bird scarers in the field if required. Installation of bird perches in the field to allow birds to sit and feed on insects and their immature stages, namely eggs, larvae and pupae. Use of pheromones for mating disruption, monitoring pest levels and mass trapping Biological Biological control of insect pests and diseases is the most important component of IPM. In a broader sense, biocontrol is the use of living organisms to manage living organisms that damage crops. 25

51 Common biocontrol agents Parasitoids: These are the organisms that lay eggs in or on the bodies of hosts and complete their life cycles on host bodies, killing the host in the process. The type of parasitoid depends on the host developmental stage in or on which it completes its life cycle such as egg, larval, pupal, adult, egg-larval and larval pupal parasitoids. Examples are Trichogramma, Apanteles, Bracon, Chelonus, Brachymeria and Pseudogonotopus species. Predators: These are free living organisms that prey upon other organisms. Examples are different species of spiders, dragonflies, damsel flies, lady bird beetles, Chrysoperla species and birds. Pathogens: These are microorganisms infecting and causing disease in their hosts, thereby killing the host. Major pathogen groups are fungi, viruses and bacteria. Some nematodes also cause disease in some insect pests. Important examples of fungi: different species of Hirsutella, Beauveria, Nomurae and Metarhizium The most important virus examples are nuclear polyhedrosis virus (NPV) and granulosis viruses. Common examples of bacteria include Bacillus thuringiensis (B.t.) and B. popillae Chemical Chemical pesticides are the last resort when all other methods fail to keep the pest population below the economic threshold. Pesticide use should be judicious, based on need and pest surveillance and the economic threshold level (ETL). This minimizes not only costs, but also associated problems. In using chemical control, it is important to clearly understand what to spray, when to spray, where to spray and how to spray, keeping in mind the following: ETL and pest-defender ratio must be observed. Relatively safe pesticides should be selected (e.g. neem-based and biopesticides). If the pest is present in strips or isolated patches, the whole field should not be sprayed. IPM practices are more relevant for vegetable and fruit crops because of consumption by humans immediately after harvest. Highly toxic pesticides or those known to have toxic residual effect should not be recommended without careful consideration. To earn more profit, farmers do not observe the waiting period between the pesticide treatment and harvesting / marketing of produce. This causes pesticide poisoning which can be fatal in some cases. 2.7 Conclusion Dealing sustainably with insect pest management is not easy. Nor is there a single strategy or measure guaranteed to work in every situation. Indeed, measures that worked in the past often become ineffective as insects build up resistance. Hence, combining other strategies with beneficial insects can be an effective integrated pest management approach. This has the advantage that if one measure fails, others are in place to help manage the pest population. Past experience shows that extensive use of a single measure, such as an insecticide over a broad area, can lead to its gradual or abrupt failure. The effective life of a control measure can be increased if it is used in conjunction with other methods. The use of 26

52 multiple strategies and measures is a basic principle of integrated pest management. IPM application goes beyond individual ownership or boundaries and needs collective action. Governments or farmer groups should be involved in the use of IPM. Institutional arrangements can create incentives for research organizations and scientists to develop IPM technologies and for farmers to adopt these technologies. IPM is knowledge-intensive and needs periodical updating by end users who are the farmers. 27

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54 3 Integrated Disease Management 3.1 Introduction The definition accepted by the American Phytopathological Society and the British Mycological Society states: Disease is a malfunctioning process that is caused by continuous irritation which results in some suffering-producing symptoms. Therefore, plant disease is a structural abnormality or physiological disorder or both, due to an organism or unfavourable conditions that may affect the plant or its parts or products or may reduce their economic value. Integrated Disease Management (IDM) is a concept derived from successful Integrated Pest Management (IPM) systems and consists of scouting with the timely application of a combination of strategies and measures. These may include site selection and preparation, utilization of resistant cultivars, altering planting practices, modifying the environment by drainage, irrigation, pruning, thinning and shading, and application of pesticide, if necessary. In addition to these traditional measures, monitoring environmental factors such as temperature, moisture, soil ph and nutrients, disease forecasting and establishing economic thresholds, are important for the management scheme. These measures should be applied in an integrated and harmonized manner to maximize the benefits of each component. The main goals of IDM are: Eliminate or reduce inoculum Reduce the effectiveness of initial inoculum Increase resistance within the host Delay the onset of disease Slow secondary cycles Application of several methods in which routine use provides disease control 3.2 Importance of the plant disease Plant disease sometimes spreads as epiphytotics and can destroy not only crops over a very large area but also crops kept in storage. The disease can occur any time and at any stage of plant growth from the time of sowing to storage. Foodgrain worth millions of dollars is lost every year due to crop disease in Asia. Well-known historical cases of plant disease include the late blight of potato by fungus Phytophthora infestance in Ireland in 1847, coffee rust by Hemilei vastatrix in Sri Lanka in 1870 and sigatoka leaf spot disease of banana by 29

55 Mycosphaerella musicola in Central and South America in In India, the infamous Bengal famine of 1942 which claimed 2 million lives was linked to leaf spot disease of rice caused by Helminthosporium oryzae Scope of integrated disease management Several synthetic fungicides have been used for disease management in commercially important agricultural crops. However, their continuous use has several side effects on agroecosystems as well consumer health. Integrated disease management strategies can address this problem. Plant disease management should always be based on the integration of basic concepts such as avoidance, exclusion, eradication, protection, resistance and therapy. Adoption of IDM for crops is of utmost importance in some developing countries where farmers are often not educated enough to follow cut-off dates for application of chemicals to the standing crops. Use of an integrated approach to plant disease management is cost-effective, renewable, eco-friendly and non-toxic to plants as well as non-targeted organisms. 3.3 History of plant disease management The history of disease management has three distinct phases, namely the era of traditional approaches, the era of fungicides/bactericides and the era of IDM Era of traditional approaches Humans have been coping with pests since the start of crop cultivation, learning through trial and error to control the agricultural environment. Methods such as flooding, destroying or using crop refuse, roughing diseased plants, tillage to expose and eliminate soil-borne pathogens, removal of alternate pathogen and insect hosts, timing of planting, crop rotation, trap crops, determining optimum planting sites, pruning and dusting with sulphur, reduced crop damage from pests. This was followed by the use of plant products from neem, chrysanthemum, rotenone, tobacco and several other lesser known plants in different part of the world. Such cultural and physical control methods are still effective today Era of fungicides As with many inventions, the development of the first fungicide was the result of good observation. The first use of brining of grain with salt water followed by liming, took place in the middle of the 17th century to control bunt, based on the observation that seed wheat salvaged from the sea was free of bunt. Up until the 1940s, chemical disease control relied upon inorganic chemicals, frequently prepared by the user. Between 1940 and 1970, a number of new chemistry classes were introduced as fungicides. The decade saw the introduction of the most widely used protectant fungicides, mancozeb and chlorothalonil. The period also marked the introduction of the first broadspectrum foliar systemic, thiabendazole and the systemic seed treatment carboxin. The first case of resistance to benzimidazoles occurred in powdery mildew in greenhouses in 1969, a year after introduction. During the 1980s, fenpropidin and fenpropimorph were key fungicides in the European cereal market, while tridemorph was used extensively for sigatoka followed by the seed treatment carboxin (Vitavax), which is highly effective on 30

56 bunts, smuts and assorted Basidiomycetes such as Rhizoctonia spp. The intensive and extensive use, misuse and abuse of synthetic fungicides during the ensuing decades caused widespread damage to the environment. Disease problems in some crops also increased following the continuous application of fungicides. This, in turn, increased fungicide use, resulting in the fungicide treadmill phenomenon. These problems, together with the rising cost of pesticides, provided the necessary impulse for limiting the use of chemicals and led to the development of the IDM concept Era of IDM The term IDM was derived from IPM (integrated pest management). A movement to develop more environmentally benign crop protection methods began in the late 1960s. Although economics was the prime driver to use crop scouting to determine spray schedules, it was a first real step towards an IPM approach. IDM calls for minimal use of pesticides, and only if necessary, giving preference to other control methods such as host-plant resistance, cultural practices and biological control. In the 21st century, agricultural sustainability has become a norm and numerous non-chemical methods for control of crop diseases such as pathogenfree seeds, disease resistance, crop rotation, plant extracts, organic amendments and biological control are considered less harmful and, therefore, having great application potential in conventional agriculture, organic farming and/or soil-less culture. No single method can provide satisfactory control of crop disease and integration of all effective and eco-friendly measures in keeping with agroecosystem management is the best strategy for crop disease control Milestones in disease management Around 200 B.C., Cato had mentioned the fumigation of trees with bitumen and sulphur. A science-based war began against crop disease in the early 1800s. In 1807, Prevost in France, recommended the use of copper sulphate treatment for wheat seed as protection against bunt and demonstrated for the first time the fungitoxic value of copper compounds. During , sulphur emerged as an effective fungicide for the control of powdery mildew disease. In 1882, Millardet in France discovered Bordeaux mixture to control downy mildew of grapevine. In 1921, Bewley developed chestnut compound to control damping-off disease as a soil drench in nursery beds. In 1926, Sanford conducted the first experiments in biological control of plant pathogens with antagonistic (Bacillus subtilis) in Canada. In 1932, Weindling suggested the use of Trichoderma spp. as a biocontrol agent. In 1943, Waksman and Schatz discovered the first broad-spectrum antibiotic streptomycin. During , the fungicidal properties of the first heterocyclic nitrogen compound captan, systemic fungicide Oxanthin, benomyl as protection against Powdery mildew fungus of cucurbits, metalaxylagainst oomycetes and fosetyl-al against phycomycetes, were investigated. In 1996, the first strobilurins fungicide, isolated from wood rotting mushroom fungi, was launched. 3.4 Concept of plant disease In 300 B.C., the Greek philosopher Theophrastus became the first to study and write about diseases of trees, cereals and legumes. He believed plant diseases were a manifestation of divine wrath. The ancient Romans worshipped the rust God Robigo, by sacrificing red dogs 31

57 and sheep, to protect grain from rust disease. The invention of the compound microscope in mid-1600 enabled scientists to observe microorganisms associated with diseased plants and they came to believe that the mildews, rust, and other disease symptoms observed on plants were associated with microorganisms. During , Louis Pasteur provided irrefutable evidence that microorganisms arise only from pre-existing microorganisms and that fermentation is also a biological and not just a chemical phenomenon. It is accepted that a plant is healthy or normal when it can discharge its physiological functions to the best of its genetic potential. The pathogen may cause disease in the plant by: Weakening the host by continuously absorbing food from host cells for its own use. Killing or disturbing the metabolism of host cells through toxins, enzymes or growthregulating substances, it secretes. Blocking transportation of food, mineral, nutrients and water through the conductive tissues. Consuming the contents of host cells upon contact Disease triangle The interaction of the three components, namely the host, its physical environment and the disease pathogen, is referred to as the disease triangle. Each side of the triangle represents one of the three components (see Figure 3.1). The length of each side is proportional to the sum total of the characteristics of each components favouring disease. When the three disease components are quantified, the area of the triangle represents the amount of disease in a plant or in a plant population. If any of the three components is zero, there can be no disease. Figure 3.1 Disease triangle Mode of disease transmission The transport of spores or infectious bodies, acting as inoculum, from one host to another at various distances, resulting in the spread of disease, is called transmission or dissemination or dispersal of plant pathogens. There are two major types of transmission of plant pathogens direct and indirect. 32

58 Direct transmission The pathogen is carried externally or internally on the seeds or planting material like cuttings, sets, tubers and bulbs. It may be: a. Germinative transmission, where plant pathogens are transmitted by seeds or propagules of host plants (e.g. loose smut of wheat, loose smut of barley, leaf blight of wheat and TMV) b. In vegetative transmission, pathogens are transmitted through tubers, bulbs, rhizomes, cuttings, graft (e.g. ring and brown rot of potato, late blight of whip smut and red rot of sugarcane) c. In adherent transmission, the propagules of the pathogens are carried over the surface of the seeds or vegitatively propagated parts (e.g. bunt of wheat, covered smut of barley, ergot of rye and bajra, and wart disease of potato) Indirect transmission The pathogen spreads itself by its persistent growth or certain structures of the pathogen are carried independently by natural agencies like wind, water, animals, insects, mites, nematodes and birds. a. Autonomous transmission: Some root rotting fungi infecting certain seasonal crops are also transmitted by this method. Wood rotting fungi such as Armillaria, Fomes and Polyporus, migrate from plant to plant through the soil. Others include root rot of cotton and wilt disease caused by Phymatotrichum omnivorum and Fusarium sp. b. Wind dispersal: Pathogens causing powdery, downy mildews, leaf spots, blasts, blights and rust diseases are transmitted through wind. c. Water dissemination: Certain soil-inhabiting pathogenic fungi and bacteria causing root and collar rots, wilts, foot and rots are likely to be transmitted to much longer distances by irrigation water, streams and rivers. d. Transmission by insects, mites and nematodes: Most viral plant diseases are transmitted through the agency of different insects (see Figure 3.2). Both sucking and chewing or/biting insects are capable of transmitting viral diseases. Insects in such cases are called `vectors for the particular viral pathogen. The insects responsible for transmission of viral diseases belong to the aphid, thrip, jassid (leaf hopper), whitefly and mealy bug species. Certain bacterial and several fungal pathogens are also known to be carried by insects. Many bacterial diseases such as cucurbit wilt and black leg of potato are transmitted by maggot while fire blight of apple is transmitted by bees. It is suspected that some viral chilli, tomato, brinjal and pigeon pea diseases have a vector relationship with mites. Nematodes are soil-borne organisms, sometimes acting as disseminators of bacterial, fungal and viral pathogens. For example, yellow ear rot disease of wheat is transmitted by ear cockle nematodes. e. Biological transmission: The higher flowering parasite Dodder is known to transmit certain viral diseases which remain `persistent in the dodder plant. f. Cattle and birds: Cattle, while feeding on contaminated fodder, ingest the viable fungal propagules into the intestine which are passed out in the dung and when such dung is used as manure, it may be source of inoculum (e.g smut spore). g. Human dispersal: Workers, while handling diseased materials, come in contact with pathogens unknowingly, which can be transferred while handling healthy plant materials. The other mode of transmission for which only human beings are responsible 33

59 is transport of disease causing pathogens over long distances to an area or country which is free from the disease through the transport of infected plant material. h. Farm implements: Pathogens are carried in bits of plant disease debris in the soil. Tools used for cutting, pruning, budding, grafting and thinning also help in the transmission of certain diseases from plant to plant. Several viral diseases are disseminated through budding and grafting operations. 3.5 Biotic and abiotic problems Many agents can initiate reactions in the host plant, causing disease and known as causal agents of the disease, are biotic or abiotic. Abiotic disorders are caused by factors such as drought, sunscald, freeze injury, wind injury, chemical drift, nutrient deficiency or improper cultural practices such as overwatering or planting too deep. Mango necrosis or black tip of mango is caused by brick kiln fumes containing SO 2, coal gas and chlorine. Despite these problems, the presence of excessive mineral or a mineral deficiency, is also responsible for major diseases. Some mineral deficiency symptoms include red leaf of cotton (nitrogen deficiency), dwarfing of cotton (phosphorus deficiency), cotton rust and little spot of alfalfa (potassium deficiency), heart rot of beet, brown heart of cabbage, internal cork of apple (boron deficiency), die back of citrus (copper deficiency), grey speck disease of oat (manganese deficiency), whiptail disease of cauliflower (molybdenum deficiency) and khaira disease of rice (zinc deficiency). Biotic plant problems are caused by living organisms, such as fungi, bacteria, viruses, nematodes, insects, mites, parasitic flowering plants and animals. The damage caused by these various living and non-living agents can appear very similar Parasitism and pathogenesis An organism living on or in some other organism and obtaining its food from the latter is called a parasite. Parasitism is the removal of nutrients from a host by a parasite. There are two major types of parasitism: obligate and non-obligate. Obligate parasites are biotrophs that depend on living cells for their existence. This group includes rust and mildew fungi, viruses, viroids, mollicutes, fastidious bacteria, nematodes, protozoans and parasitic plants. Non-obligate parasites can be biotrophic or necrotrophic. Necrotrophic pathogens kill host cells in advance of colonization. Necrotrophs typically use enzymes and toxins to kill the cells they feed on. Facultative saprophytes are parasites that typically depend on living material, but can utilize necrotic materials in situations where no live material is available. Facultative parasites live predominately as saprophytes, but under specific conditions can parasitize living organisms. Pathogenicity is the ability or capacity to incite disease. The terms virulence and aggressiveness are often used in relation to pathogenecity. Aggressiveness is the relative ability to colonize and cause damage to plants. In short, it is whether the pathogen causes little or much disease under standard conditions. Virulence is the degree of pathogenicity of a given pathogen. Pathogenesis is the sequence of progress in disease development from the initial contact between a pathogen and its host to the completion of disease symptoms. Pathogenesis consists of three steps, namely pre-penetration, penetration and postpenetration. Pre-penetration is the stage of interaction of host pathogen before it enters the 34

60 host. Once a pathogen reaches a suitable infection site on the plant surface, it must breach a series of barriers to gain entry into the host before establishing a parasitic relationship during the penetration stage. After successful penetration, the pathogen proceeds to establish proper infection. This stage is called invasion. After successful infection, the pathogen draws nourishment from the host, starts multiplying and secretes chemical substances that express the disease symptom. The haustoria absorb nutrients from the host and supply it to the main body of the pathogen Disease cycle Plant disease cycles represent pathogen biology as a series of interconnected stages of development including dormancy, reproduction, dispersal and pathogenesis. The progression through these stages is determined by a continuous sequence of interaction among host, pathogen and the environment. The main events of the stages comprising the disease cycle include production and dissemination of the primary inoculum, primary infection, growth and development of the pathogen, secondary infection and overwintering (see Figure 3.2). Figure 3.2 Disease cycle 1. The primary inoculum is the part of the pathogen (bacterial or fungal spores or fungal mycelium) that overwinters (overseasons) and causes the first infection of the season, known as primary infection. 2. Dissemination refers to the spread or dispersal of the pathogen from an inoculum source to a host. Dissemination can occur by wind, splashing rain, insects, infested pruning tools, infected or infested transplants and other means. 3. Primary infection occurs when the pathogen comes into contact with a susceptible host under favourable environmental conditions. Most fungal and bacterial pathogens require free water for spore germination; consequently, infection is favoured by prolonged warm and wet periods. 35

61 4. The growth and development of a pathogen usually occurs on or within infected plant tissue. Fungi grow and spread within the host by means of mycelium. Bacteria spread by rapidly increasing in numbers. 5. Secondary infection results from spores or cells produced following primary infection or from other secondary infections. The secondary infection cycle can be repeated many times during the growing season. The number of cycles is dependent on the biology of the pathogen and its host and the duration of environmental conditions needed for infection. 6. Overwintering or overseasoning is the ability of a pathogen to survive from one growing season to the next. 3.6 Causes and identification of plant diseases A plant disease is the result of close interaction between the host plant and the disease inciting agent. Many agents initiate reactions in host plants causing disease and are known as the cause of disease. Such agents include living and non-living as well as viruses and are described in section Classification of plant diseases Plant disease may be classified in various ways on the basis of casual agencies, spread and severity of infection, their perpetuation and transmission, the part of host affected and symptoms produced by host plants Classification based on causes of diseases On the basis of disease causes, these can be divided into non-infectious and infectious. a. Non-infectious diseases: These are not caused by living organisms but by lack of suitable environmental conditions, nutritional deficiencies and physiological disorders (e.g. heat canker of flax caused by high temperature, apple scald and black tip mango caused by injurious atmosphere, whiptail disease of cauliflower caused by deficiency of molybdenum and tip rot or necrosis of mango fruits caused by boron deficiency). b. Infectious diseases: These are caused by living organisms such as bacteria, mycoplasmas, fungi, nematodes, algae and protozoans as well as viruses and are parasitic in nature. Such diseases show symptoms and can be easily transmitted to healthy plants Classification based on spread and severity of infection Based on geographical distribution and severity of infection, plant diseases are classified into endemic, epidemic or sporadic categories as insect pests Classification based on the part of host infected Such diseases may be localized or systemic. In localized infection, the disease affects a particular part or organ of the host plant, for example root disease, stem disease, foliage disease and spike disease, depending on the organ infected. In systemic infection, the disease spreads throughout the plant body. 36

62 Classification based on perpetuation and dispersal of diseases Such diseases are categorized as follows: a. Soil-borne diseases: Inoculum of the disease-causing pathogen remains in the soil and penetrates the plant, resulting in diseased condition (e.g. root rot, wilt). b. Seed-borne diseases: The microorganisms are carried along with seeds and cause diseases under congenial condition (e.g. damping off). c. Air-borne diseases: The microorganisms are spread through air and attack plants, causing diseases (e.g. blight, rust and powdery mildew). d. Water-borne disease: This category includes diseases where the primary inoculum is perpetuated and transmitted through water (e.g. blight of paddy). e. Diseases spread by insects: Viral diseases are spread by insects known as vectors Classification based on disease symptoms Such categories include smut, anthracnose, canker, mosaic, powdery and downy mildew damping off, rots and gall Symptoms of plant diseases Symptoms are external or internal expressions of a plant indicating that it is suffering. Generalized symptoms may be classified as local or systemic, primary or secondary, and microscopic or macroscopic. Local symptoms are physiological or structural changes within a limited area of the host tissue, such as leaf spots, galls and cankers. Systemic symptoms involve the reaction of a greater part or all of the plant, such as wilting, yellowing and dwarfing. In general, the systems produced by specific groups of casual organisms can be listed as follows: Fungi and fungi like organisms (FLOs) such as Pythium and Phytophthora collectively cause more diseases in the plant than the pathogen as a whole. Bacterial diseases in plants may affect stems, leaves or roots or be carried internally. The most obvious symptoms of virusinfected plants usually appear on leaves but some viruses may cause striking symptoms on the stem, fruits and roots. Abnormal growth and development of plant tissues often follows because of hypertrophy (increased cell size) and hyperplasia (increased number of cells) caused by the interaction of chemicals produced by the pathogen and host tissues. Tissues show abnormal growth pattern, resulting in altered morphology and physiological functioning of the affected part or entire plant Disease diagnostic procedures Proper diagnosis may be extremely important in preventing the problem on other plants or in preventing the problem in future. How does a plant pathologist diagnose plant problems? The diagnostician must have good observation skills and also be a good detective. An open mind is important until all facts related to the problem are collected. The possibility of multiple causes must also be considered. Control measures depend on proper identification of diseases and causal agents. Therefore, diagnosis is a very important part of a plant pathologist's training. Without proper identification of the disease and the disease-causing agent, disease control measures can be a waste of time and money and result in further plant losses. 37

63 Sample collection methods The kits for the collection of diseased plant samples from the field are plastic and paper bags, pruning shears, a pruning saw, wire twist ties, paper towels, a knife, a hatchet, an increment borer, plastic/rubber gloves, a trowel, a shovel, a soil probe, rubber bands, a 5-10X magnification hand lens, forms, a pencil, labels, vials/jars with lids, padded collection boxes, a camera, maps, field manuals, disinfectant for hands and tools, and a portable soil ph and soluble salts meter. After deciding what to include in the sample, the following procedures are suggested for obtaining, packaging and submitting the sample: a. Obtain fresh material in a reasonable quantity with several examples of the various symptoms. Be certain to include as many identifiable stages of the disease as are represented. Most recently developed symptoms usually afford the best material for diagnosis. b. Lift roots carefully so as not to leave feeder roots or rotted roots behind. Include about 1 l of soil for ph, soluble salts and possibly a nematode assay. c. Place samples in plastic bags of appropriate size, including a paper towel for a blotter, if the sample is very wet. Duplicate dry samples are recommended if the sample is succulent or fragile. d. Wrap a wire twist-tie around the stem at the ground line to keep the soil above-ground plant parts. Label samples accurately. Place the entire sample in a paper or unsealed plastic bag. e. Keep the samples cool and protect from crushing. f. Obtain the following information from the grower: 1. Host: Cultivar/variety, age, propagation method, site preparation, names, dates and rates of fertilizer, pesticide history and schedule, growth regulator applications, pruning, pinching, transplant, omissions or additions to usual/conventional culture programme. 2. Irrigation: Frequency, rate, timing, water quality, determination of need. 3. Soil/media: ph, soluble salts, texture, drainage, homogeneity, aeration, temperature, planting depth, cultivation, cropping history, earth moving/ construction, burial/disposal site, trash burning. 4. Environmental conditions: Temperature, humidity, ventilation, wind, lightning, exposure, light intensity, air quality, heating/cooling method during syndrome development. 5. Date of first symptoms and rate of syndrome development, coincident with any treatment or environmental event. 6. Recent human, animal, insect or mite activity around or on symptomatic plants. 7. Habits of plants in question, predisposition (plant made more susceptible) by cultural or environmental conditions. g. Make pertinent observations. 1. Spatial and chronological pattern of disease in crop or on individual plant. Are symptoms different or consistent, uniform or scattered? 2. Are symptoms spreading across the crop or progressing on individual plants? 3. What is the frequency and intensity of the syndrome? 4. Any signs of pathogen/causal agent? (Fruiting structures, chemical residues, insects/mites and frass). 5. Any evidence of host recovery? 6. Do nearby plants (same or different) show any symptoms? Are root zones shared? 38

64 7. Inspect interior, crown, roots of plant. Cut open stems, crowns, flowers, fruits, and roots. Are there any hidden, internal symptoms/signs of disease? Sample submission methods a. Take samples before applying pesticides, otherwise the ability to recover pathogens may be limited. b. Submit generous amount of plant material representing a range of symptoms. c. Do not add water or pack a wet sample. d. Keep samples refrigerated after collection until submission. After collection of good samples, do not let these bake in the sun or on the back seat of a car, prior to submission as this will ruin the samples. e. Do not mix different samples in the same submission bag. Moisture from root samples will cause foliage samples to decay if mixed together. f. Plant disease identification procedures do not utilize soil. Excess soil can be hand shaken from root systems, but leave enough soil to keep roots at field moisture levels. g. Important to mark sample packages Warning if the sample has thorns or spines. h. All samples must be accompanied with a completed Plant Clinic Diagnostic Form available at all extension offices or online. Provide complete information asked in the form and keep it separate from the sample. Complete a separate form for each sample and plant problem. i. Remember to note recent pesticide history on the Plant Diagnostic Form accompanying the sample. j. Mail samples early in the week to avoid the weekend layover in the carrier facility. k. For emergency samples, use overnight courier services or surface mail. Complete mailing addresses and map locations are necessary if owners want to be informed of diagnosis or the site must be revisited Diagnostic methods Diagnostic tests for identification of biotic causal agents A major problem in the identification of biotic causal agents is the inability of some infectious pathogens to grow on artificial media. Viruses, as well as some fungi (e.g. powdery and downy mildew causing agents) and some prokaryotes (e.g. phytoplasmas), require a living host in order to grow. In cases where the plant pathogen finds it difficult or impossible to grow on artificial media, other methods may be used for their detection, such as the use of serological tests for viruses. Viral identification is often accomplished utilizing the ELISA (enzyme-linked immunosorbent assay) method. Other techniques for virus identification include negative staining and electron microscopy to view the viral particles in plant tissue or suspensions. PCR (Polymerase Chain Reaction) and ELISA tests, as well as other laboratory tests, may be used for organisms that grow on artificial media. Additional tests may include analysis of fatty acids in organisms, carbohydrate utilization (a BIOLOG test), and enzyme activity testing (pectinase, isozyme patterns). Diagnostic tests for identification of abiotic plant disease causal agents It is extremely important to look for abiotic factors that may be important in observed symptoms. Soil and water tests may be necessary to determine ph, nutrient composition, salinity and other factors such as pesticide residues that may induce various symptoms. It 39

65 may also be important to get samples of plant tissue analysed for nutrient content to determine if there are macro or micronutrient deficiencies or toxicities. 3.7 Plant disease management The goal of plant disease management is to reduce the economic and aesthetic damage caused by plant disease. Traditionally known as plant disease control, the term control, however, is considered as absolute and rigid under today s social and environmental values. Disease management can be viewed as proactive whereas disease control is reactive, although it is often difficult to distinguish between the two concepts, especially in the application of specific measures Principles of plant disease management Avoidance of pathogen: It comprises proper selection of the geographical area, selection of the field, sowing date, choice of disease-escaping varieties, selection of disease-free seed and planting stock, and cultural practices. Exclusion of pathogens: It includes quarantine measures, seed certification, plant disease notification and prevention of sale of diseased plants. Reduction and eradication of pathogen inoculum: This can be achieved through cultural, physical, mechanical, biological and chemical practices. Resistance to pathogens: Host resistance and production of resistance varieties. Integrated approach: It combines disease management strategies with the overall aim to develop sustainable disease management systems based on a sound understanding of the entire crop ecosystem Disease epidemiology and factors affecting spread of disease Epidemiology or epiphytology is the study of the outbreak of a disease, its course, intensity, cause and effects, and the various factors governing it. Based on occurrence and geographical distribution, these are classified as endemic, epidemic and sporadic as described earlier. An epidemic may cause widespread or mass destruction of crop in a short time or may persist for long periods depending on the host, pathogen and environment. A disease is sometimes sporadic and assumes epidemic proportions under special circumstances. The essential conditions for an epiphytotic or the factors governing epidemics can be grouped under the heads of Nature of host, Nature of pathogen, and Environment Components of IDM Quarantine and regulatory measures, cultural, genetic resistance, physical and mechanical, biological and chemical. 40

66 Quarantine and regulatory measures Plant quarantine is the legally forced restriction on the movement of diseased plant materials or of fungi, bacteria or viruses that cause disease in plants. Quarantine legislation has been enacted in most agriculturally advanced countries. When plant pathogens are introduced into an area for the first time, these are likely to have a much more catastrophic impact than existing pathogens. Some of the worst plant disease epidemics, (e.g. downy mildew of grapes in Europe and bacterial canker of citrus) are examples of failure of quarantine regulations. It is extremely difficult to predict accurately whether an exotic organism will become established, and once established, become economically important. The purpose of a national quarantine law is to prevent the introduction in the country of any insect, fungus or other pest, which is or may be destructive to crops. The significance of plant quarantine has increased in view of the liberalization of the international trade in plants and plant material in the wake of the Sanitary and Phytosanitary (SPS) Agreement under the World Trade Organization (WTO). Phytosanitary certification of agricultural export commodities is also undertaken through the scheme as per International Plant Protection Convention (IPPC), Cultural practices These have an important role in plant disease prevention and management. The benefits of cultural control begin with the establishment of a growing environment that favours the crop over the pathogen. Reducing plant stress through environmental modification promotes good plant health and helps reduce damage from some plant diseases. Deep ploughing of the field exposes propagules to higher temperatures and physically kills the pathogen. This can be regarded as dry soil solarization. Summer ploughing is effective in reducing populations of cyst nematodes and increasing wheat yield. Flooding of the field is similar to soil disinfestation. Long-term summer soil flooding, with or without paddy culture, decreases populations of soil-borne pathogens. Sanitation practices that exclude, reduce or eliminate pathogen populations are critical for managing infectious plant diseases. It is important to use only pathogen-free transplants. In order to reduce the dispersal of soil-borne pathogens between fields, stakes and farm equipment should be decontaminated before being moved from one field to the next. Pathogen survival from one season to another may be reduced by crop rotation and destroying volunteer plants. Avoid soil movement from one site to another to reduce the risk of transferring pathogens. For example, sclerotia of Sclerotinia sclerotiorum and Sclerotium rolfsii are transported primarily in contaminated soil. Minimizing wounds during harvest and packing, reduces post-harvest disease problems. Depending on crops and other factors, soil sanitation can be achieved to some degree by solarization. Crop rotation is a very important practice, especially for soil-borne disease control. For many soil-borne diseases, a three-year rotation using a non-host crop, greatly reduces pathogen populations. This practice is beneficial for Phytophthora blight of pepper and Fusarium wilt of watermelon, but longer rotation periods of between five and seven years may be needed. Crop rotation should be done in such a way that no two subsequent crops have the same pest spectrum. Vegetable fields should be located as far away as possible from inoculum and insect vector sources. 41

67 Weed control is important for the management of viral diseases. Weeds may be alternate/collateral hosts for many important vegetable viruses. Eliminating weeds might reduce primary inoculum. Non-host cover crops help to reduce weed populations and primary inoculum of soil-borne pathogens. Excessive handling of plants, such as in thinning, pruning and tying, may spread pathogens, particularly bacteria. It is advisable to handle plants in the field at their driest stage. Because some pathogens only enter the host through wounds, avoid situations that promote plant injury. When applicable, plants can be staked and tied for improved air movement in the foliar canopy. A more open canopy reduces dampness, discouraging growth of most pathogens. Soil aeration and drying can be enhanced by incorporating composted organic amendments in the soil. The pathogen inoculum can be reduced by removing plant material (infected and healthy) after the harvest. Polyethylene mulch can be used as a physical barrier between soil and plant parts above the ground. This is an important practice for fruit rot control in vegetables in the field. Highly UV-reflective (metalized) mulches repel some insects that transmit viruses as vectors Genetic resistance It is the inherent ability of a plant to prevent or restrict the establishment and subsequent activities of potential pathogens. A particular host may be resistant to all races of the pathogens (horizontal resistance) or may be effective against a few races of the pathogens (vertical resistance). Control measures using the development of new varieties resistant to diseases, are being applied in almost all economically important plants. If a new variety with high yield is not resistant to local pathogens and pests, it cannot be recommended to farmers. Breeding disease resistance is achieved by methods such as introduction, selection, hybridization, mutation, polyploidy, budding and grafting. For resistant varieties, farmers should contact nearest research centres/local extension functionaries Physical and mechanical measures Mechanical and physical controls kill pathogens directly or make the environment unsuitable for their survival. These include: 1. Collection and destruction of disease-infected plant parts. 2. Soil sterilization at 50 C to 60 C for about 30 minutes kills all soil-borne pathogens. 3. Some seed-borne diseases can be treated by immersing infected seeds in hot water at temperatures as follows: loose smut of wheat (52 C for 11 min), leaf scald (50 C for 2-3 hours), red rot (54 C for 8 hours) and ratoon stunting of sugarcane (50 C for 3 hours) and black rot of crucifer (50 C for minutes) 4. Hot air treatment removes excess moisture from plant organs and protects from fungal and bacterial attack. Several virus-infected dormant plants are treated by hot air at temperatures between 35 C to 54 C for 8 hours. 5. Refrigeration is the most common method of preventing post-harvest diseases of perishable fruits and vegetables. 6. Colour traps like yellow for aphids and whitefly, and blue for thrips can be used for control of insect vectors of viral diseases. 42

68 Biological control The use of biocontrol agents for disease management is increasing, especially among organic farmers. Biocontrol agents are considered safer for the environment and the farmer than conventional chemicals. Examples of commercially available biocontrol agents include the fungi Trichoderma viride/harzianum and Gliocladiumvirens, anactinomycete Streptomyces griseoviridis, and a bacterium Bacillus subtilis. Bacteriophages (phages) are an effective biocontrol agent for managing bacterial spot on tomato. Phages are viruses that exclusively infect bacteria. Paecilomyces lilacinus, a common saprobic, filamentous fungus has been isolated from a wide range of habitats and frequently detected in the rhizosphere of many crops. The fungus has shown promising results as a biocontrol agent against destructive root-knot nematodes. Cross protection is a modern biocontrol method for disease management. In this method, the mild strain of the virus or microorganisms is inoculated in the host plant. This protects host plants from viruses and microorganisms that can cause severe damage (e.g. papaya ring spot disease and citrus tristiza disease). A limitation biocontrol agents is the inability to survive in certain field conditions. However, biocontrol agents can improve disease management when integrated with other management options described in this document. A number of botanicals were tested against fungal disease like sheath blight. Some commercially used botanicals against plant diseases are extract of neem (Azadirachta indica, A. Juss), garlic (Allium sativum, Linn., eucalyptus (Eucalyptus globulus, Labill.), turmeric (Curcuma longa Linn.), tobacco (Nicotiana tabacum Linn.), ginger (Zingiber officinale Rosc.) and essential oils of nettle (Urtica spp.), thyme (Thymus vulgaris Linn.), eucalyptus (Eucalyptus globulus Labill), rue (Ruta graveolens Linn.), lemongrass (Cymbopogon flexuosus (Steud. Wats.) and tea tree (Melaleuca alternifolia). Foliar sprays with neem 20 ml/l or neem 3ml/l were found significantly effective in reducing sheath blight and increasing grain yield. Leaf extracts of Eucalyptus globosus (5 per cent) and Azadirchta indica (5 per cent) have exhibited greater antifungal activity against A. brassicae and Albugo candida and significantly reduced the severity of Alternaria blight and white rust diseases Chemical control When all the above methods are not effective and pathogens are destroying crops, chemical measures become necessary. Fungicides and bactericides are important in many disease management programmes. It is important to remember that chemical use should be integrated with other appropriate methods described in this chapter. Information regarding a fungicide's physical mode of action helps producers in improving fungicide application timing. The physical mode of action of fungicides can be classified into four categories, namely protective, after infection, pre-symptom, and anti-sporulant (post symptom). Protectant fungicides include the bulk of foliar spray material available to producers. In order to be effective, protectant fungicides, such as copper compounds and mancozeb, need to be applied on the leaf (or plant) surface prior to pathogen arrival. Systemic (therapeutic) fungicides, based on their level of systemic nature, are active inside the leaf, penetrating at different rates through the cuticle. Systemic fungicides may stop an infection after it starts and prevent further development of the disease. 43

69 3.8 Constraints in IDM and future thrust After an in-depth study of constraints to IDM implementation in developing countries, the consultant group of the IDM Task Force has identified the following institutional, sociological, economic and political issues: a. Institutional: IDM requires an interdisciplinary approach to solve pest problems and the lack of coordination among different institutions is a challenge. Research programmes based on farmer needs are lacking. b. Informational: Farmers and extension workers lack of information on IDM. Lack of IDM training. c. Sociological: Some farmers find IDM risky compared to use of pesticides alone. d. Economic: Lack of funds for training farmers and extension workers on the use of IDM. Other constraints: 1. By offering seeds, fertilizer and fungicide to farmers on credit, fungicide dealers can jeopardise implementation of IDM. 2. Pesticides companies popularize their products through mass media. 3. Farmers on becoming more dependent on subsidies get used to seeking financial support for adopting NPM (Non-chemical Pest Management) methods. 4. Biopesticides, biocontrol agents and other IDM components are not readily available. 5. Large farmers discourage small farmers from adopting IDM methods by emphasizing their risky and unstable nature. 6. Scientific community constrained in recommending IDM for feat that farmers may seek compensation in case of failures. Future thrust: The above considerations show that the use of fungicide reduction techniques in and around the home, workplace and/or school, and community, is a wise move towards ecological stewardship. Recent market trends find the public increasingly aware of the need of fungicide-free consumption with the growth in sales of virtually every organically grown commodity, from vegetables to pet food to lawn care products. IDM practices that emphasize fungicide reduction and organic practices, provide real-world solutions for a healthier environment. 3.9 Conclusion Disease is caused in plants by biotic and abiotic means. This chapter summarizes the history, types of plant disease and their integrated management. The history of plant disease management shows the evolution of traditional, chemical and integrated approaches to disease management. Abiotic means environmental factors while biotic includes microbes, phanerogamic plants, viruses and nematodes, among others. Abiotic and biotic factors cause several diseases in plants like necrotic symptoms, abnormal growth and development of plant tissues, gummosis, wilting, rust and mildews. The factors responsible for the transmission of these diseases are described in this chapter as the disease triangle and disease cycle. The success and sustainability of IDM, especially for resource-poor farmers, greatly depends on their involvement in generating locally specific techniques and solutions suited to their particular farming systems and integrating control components that are ecologically sound 44

70 and readily available. Training and awareness promotion among farmers, disease survey teams, agricultural development officers, extension agents and policymakers are important for the successful implementation of IDM strategies. All direct stakeholders including farmers, extension workers and local crop protection technicians should have a practical understanding of the ecology, etiology and epidemiology of major crop diseases. Intensive training through participatory approaches can empower farmers with appropriate knowledge to become better managers of their own fields, translating this knowledge into appropriate decision-making tools and practical control tactics. 45

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72 4 Principles and Concepts of Integrated Nematode Management in Major Crops 4.1 Introduction Plant parasitic nematodes are hidden enemies of crops and the symptoms of the damage caused by these are not easily recognizable. Their microscopic size also reduces the chance of nematodes being recognized as the causal organisms of damage. Some nematodes predispose plants to other pathogens, while others act as vectors. Worldwide, these worms are estimated to cause crop yield losses of over $78 billion per year. Such losses are estimated to be over 14 per cent and 9 per cent of total losses in developing and developed countries respectively. Nematode damage is much higher in tropical than in temperate regions. The limited nematological expertise and lack of awareness, widespread occurrence of highly pathogenic nematode species, temperatures that are conducive for reproduction for most of the year and longer crop growing seasons, are among major reason for greater nematode damage in the tropics. Most developing countries in subtropical regions have inadequate expertise to identify, demonstrate and manage crop damage caused by nematodes. Economically important nematodes associated with crops Root-knot nematode (Meloidogyne incognita, M. javanica, M. arenaria, M. graminicolaand and M. indica) Reniform nematode (Rotylenchulus reniformis) Cyst nematode (Heterodera zeae and H. cajani) Lesion nematode (Pratylenchus coffeae, P. indicus, P. thornei and P. zeae) White tip nematode (Aphelenchoides besseyi) Ufra nematode (Ditylenchus angustus) Burrowing nematode (Radopholus similis) Citrus nematode (Tylenchulus semipenetrans) Potato cyst nematode (Globodera rostochiensis and G. pallida) Wheat seed gall nematode (Anguina tritici) Rice root nematode (Hirschmanniella spp.) Stunt nematode (Tylenchorhynchus brevilineatus) In India, nematodes are estimated to cause a national loss worth Rs 21, million annually. 47

73 4.2 Assessment of the situation The extent of crop damage (reduction in yield) by plant parasitic nematodes is directly related to their population. Here, quantitative estimation of nematodes is imperative before control measures are initiated. Economic losses start when initial nematodes populations (Pi) reach threshold or pathogenic level. Mathematical models have been developed to forecast the extent of crop losses based on data on Pi, weather parameters and epidemic factors, among others. Figure 4.1 Knot/Gall formation due to root knot nematode infestation on bitter gourd roots Figure 4.2 Reniform nematode and its egg mass Plant parasitic nematodes or eelworms are microscopic worms found in the soil around host roots and are often ectoparasitic, but many endoparasitic species are abundant in rhizosphere soil. Some plant-parasitic species are less harmful. Those causing noticeable damage are considered pathogenic. Soil-inhabiting ectoparasitic forms become economically important when their population reaches the so-called economic threshold and causes considerable damage. For management options, such as chemical, biological, physical or cultural, accurate nematode identification is of utmost importance. Determining pathotype or race may also become important in a particular group such as Heteroderidae. It is equally important to know the species, host and the pathological impact of the species on plant growth and yield. 48

74 Different stages in nematode assessment and management Stage 1: Look for and assess of symptoms of nematode damage Stage 2: Collection of soil and plant tissue samples Stage 3: Extraction of nematodes from samples Stage 4: Identification of nematodes Stage 5: Nematode density assessment Stage 6: Nematode damage analysis Stage 7: Management decision-making Sampling Having observed symptoms indicating possible nematode infestation, the next stage is the collection of samples from affected plants and the soil around roots for laboratory analysis to identify the nematodes and, if possible, their density. The following field characteristics have implications for the sampling method and should, therefore, be considered at this stage: Aggregated distribution of nematodes due to host root system and the seasonal behaviour of the nematode Crop type and history Areas planted to different varieties Soil moisture Soil compaction Soil type Temperature and seasonal change Losses from nematodes are often underestimated because nematodes are hidden in the soil. Testing for nematodes is needed to diagnose nematode-related problems and is also useful before taking a decision on planting resistant varieties or rootstocks, soil fumigation or treatment with a nematicide Sampling to determine presence, absence and abundance of key species Surveying large areas for the presence or absence of plant nematodes is conducted using statistical designs to obtain a reliable estimate of nematode populations. Fields and patches in a large area should be selected at random and sampling procedure should be based on standardized techniques. Nematode population assays should be conducted to determine both quality and quantity of important species and to relate their population levels to crop damage. Non-agricultural areas adjoining cultivated land and non-crop plants in and outside that area should also be surveyed to identify potential pest problems. This will help in understanding alternative hosts and biological aspects of nematode species. Biological data, including damage symptoms, life cycles, population trends and agroclimatic information on soil types, climatic conditions, cropping sequences and the times of sampling are also important as nematode populations depend on these. This knowledge is of utmost importance when control measures are contemplated. 49

75 Figure 4.3 Cobb s decanting and sieving method for extraction of nematodes Soil, plant and roots are tested for presence of nematodes. Only plant parasitic or free living nematodes can be counted from the soil. A qualitative test (visual examination) of roots is needed to determine the presence of galls or nematode egg masses, females or cysts. The damage caused, affected plant part and nature of damage, whether on external or internal part of the affected host and symptoms on the host, and whether above and below the ground, are also important in the identification of economically important nematodes. Ectoparasite: The nematode remains outside of the plant and uses its stylet to feed from the plant root cells Semi-endoparasite: The nematode penetrates the plant partially and feeds at some point in its life cycle Migratory endoparasite: The nematode spends much of its time migrating through root tissues destructively, feeding on plant cells Sedentary endoparasite: The J2 stage of the nematode invades the plant near a root tip and migrates through the tissue to developing vascular cells. The nematode is completely embedded in the root during its initial stage of development, but later the cyst nematode protrudes from the root Determining host status of intended or current crops Phytoparasitic nematode parasitize plants for food. Generally, these nematodes search the host by active movement and rarely by passive movement. Host root exudates are the main source of attraction for the nematode which remains in the rhizosphere during the active root growth stages of the host. Root exudates are not the result of plant and parasite interaction, but are naturally produced during the growth of the host Population levels in relation to economic thresholds The population level for presence, absence and abundance differs from species to species. Often, the number of nematodes per gram of soil and disease-causing threshold level of population are considered in quantitative reports. Knowledge of the number of plant parasitic nematodes present, helps to determine control strategies. If the population level is high enough to cause economic damage (i.e. at or above 50

76 the economic density threshold for that species), then control strategies are recommended. Table 4.1 Economic thresholds for soil and root populations of plant parasitic nematodes Nematode Soil (Nematodes/kg soil) Economic threshold Root (Nematodes/50g dry root) Root Lesion Strawberry Crops Vigorous growing processing tomato varieties Most other crops Root Knot 0 0 Carrot, parsnip, tomato Onions, potatoes Most other crops Pin Most crops Dagger Most crops Bulb and Stem Most crops Sugarbeet Cyst Soybean Cyst larvae or eggs (> 250 cysts) larvae or eggs (> 250 cysts) --- Sugarbeet, cruciferous crops --- Soybean 4.3 Avoidance of nematode problem Nematode characteristics limit their long-distance dispersal, including their restricted active movement, obligate parasitism, narrow host ranges, sharp population decline without a host, and dependence on environmental conditions and crop management practices for survival. Thus, long-distance dispersal of the parasites is largely passive and by chance. The key means of dissemination include movement of soil on equipment and plant parts, crop transplants, water, animals and contaminated containers such as burlap bags. Measures to avoid dissemination and establishment of new nematode problems, should be a component of national/regional nematode IPM programmes Selection of biogeographic area A nematode may not be found naturally within a particular area or it may not establish itself in an area because the soil and climatic environment are unsuitable. Distribution largely depends on farming factors. Thus selection of a particular geographic area free from a particular nematode will help in the production of disease-free crop by minimizing nematode infestation Selection of planting site While naturally ubiquitous, there are places where pathogenic nematodes either do not exist or are found at a subminimal level. Such areas are identified as disease-free. Thus, in India, potato seeds produced in places other than the Niligiri hills are most sought after by potato 51

77 growers since these are cyst nematode free-areas. In the Netherlands, many commercial growers prefer nematode-free sites for the cultivation of orchids and cole crop vegetables. Choosing an un-infested field site is the best way to avoid problems with lesion nematodes Selection of planting date The nematode life cycle depends on climatic factors and adjusting the planting time can help avoid nematode damage. Crops may even be planted in winter as nematodes are not active at low temperatures. Early potatoes and sugarbeets grow in the soil during the cold season and escape cyst nematode damage as the nematodes are not active Selection of planting stock In plants, propagated by vegetative means, nematodes can be eliminated by selecting the vegetative part from healthy plants. The golden nematode of potato, the burrowing, spiral and lesion nematodes of banana can be eliminated by selecting nematode-free plant material. The wheat seed gall nematode and rice white tip nematode can be controlled by using nematode-free seeds. 4.4 Exclusion of problem nematodes Crop losses caused by plant parasitic nematodes can be avoided by preventing the introduction of specific nematodes or nematode problems in unaffected areas. The focal point of exclusion is the target nematode species. Exclusion procedures should be used as a first-order defence to prevent dissemination and establishment. Exclusion procedures include sanitation, certified plant material, nematode-free soil or planting media, population reduction or eradication procedures and regulatory activities. Quarantine methods can prevent or check the spread of plant parasitic nematodes. Certified plant material and nematode-free planting media or equipment should be used for nematode exclusion. All available exclusion procedures should be considered in system evaluation and design of the INM programme Inspection, certification, quarantine Cultivation of crops in a pest-free area is preferable to nematode management. Pre-sowing field inspection helps in avoiding nematode-infested plots and seeds. Identification of a pestfree area enables production of quality seeds and reducing the risk of movement of nematodes from one location to other. Nematodes are usually spread by the transfer of infested seed material and propagate. Often, the transport of soil adhering to plant material and vehicles, also pose the threat of nematode dispersal. Seed material that has been tested/certified as free of Potato Cyst Nematode (PCN), which is the most serious potato pest problem, should be used if potato tuber is to be planted. The seed lot has to be inspected, tested for nematode absence and certified by the designated authority. In Australia, commercial potato crop cultivation is prohibited without PCN certification. Potato seed also cannot be marketed without such certification. All seed producers and growers selling seed from commercial crops should be registered under certified schemes in all States of Australia. 52

78 Quarantine measures aim to restrict the movement of infected plant material and contaminated soil across international borders and also to areas unaffected by pests within national borders Treatment of infected plant material The use of planting material free of disease or pathogen is the best method of nematode exclusion. However, if such material is not available, infected plant material must be treated before planting. The generally suggested treatments are exclusion/removal of the infected part, hot or cold treatment, fumigation or dressing, drenching, soaking or seed/seedling dip. Treating peeled (pared) banana suckers for minutes in hot water at 50 C will reduce nematode and weevil infestation in the plant crop and successive cycles (ratoons) of both plantain and cooking banana Restriction of spread people, equipment, animals, water, wind Nematodes are spread by water run-off, infested plant material and infested soil. Plantfeeding nematodes can move only between a few centimetres to a few metres, on their own. Typically, nematodes are spread by the movement of infested soil and/or infected plants. Potato cyst nematode can easily be spread by the movement of the host plant or the soil attached to the plant, bulb, pre-infested tree and agricultural equipment. Root knot nematode may be spread by planting infested tubers, which do not necessarily show symptoms. The movement of nematodes in soil is quite slow if unaided. Active movement might be between 1 to 2 metres per year and may only take place if food is available within that radius. However, significant movement in nematodes is generated by natural and anthropogenic forces. Nematodes with stages resistant to desiccation may be spread widely and for long distances by blowing dust. The spread of cysts of Heterodera avenae by wind, across desert regions between cereal production areas, has been measured in Australia. Nematodes are rapidly spread through and among fields by irrigation water run-off, engineered drainage systems and flood water. Tillage and land levelling also rapidly spread nematodes across a field. Many nematodes, particularly endoparasites, are consumed in plant material by birds and other animals (Martin). Nematodes are also spread by contaminated soil adhering to vehicles and custom tillage and harvesting equipment. The movement of the soybean cyst nematode (Heterodera glycines) is associated with the purchase of used equipment from established soybean areas for use in new areas. Thus, the most significant factor determining nematode spread is not the organism s innate activity but the unpredictable effects of physical conditions, cultural operations, topography and market patterns. Sanitation and good cultural practices are the best preventive measures against nematode spread Grower and public education Awareness of nematode damage to crops is minimal among farmers and extension workers. Extension workers should be made aware of the problem and demonstrations organized to familiarize farmers with nematode damage and the benefits of control. 53

79 4.5 Eradication, reduction or management Nematode eradication is difficult and there is a gradual shift towards the concept of management of the pest. The focus is shifting towards Integrated Nematode Management (INM) systems relying more on biological control, based on ecological and economic considerations Cultural practices, environmental manipulation Most nematode management programmes focus on measures aimed at reducing the initial nematode population density and/or the suppression of pest reproduction. The following nematode management measures limit crop damage: Fallowing: As obligate parasites, nematodes cannot survive without a host and moisture for more than a few weeks. Hence, keeping the field fallow for a period of time would reduce the nematode population drastically. Flooding: Keeping land submerged in water decreases soil oxygen and kills nematodes by asphyxiation. The practice may not be economical but is effective against root knot and stunt nematodes on vegetables. Cover crops: Some cover crops are naturally suppressive of certain nematode species. The cover crop plant may be a non-host and, therefore, the nematodes starve, which reduces their population. Crop rotation: Cultivating a non-host crop in the period between the growth cycles of two susceptible crops, reduces the nematode population level below the damage threshold. Crop rotation with mustard/chickpea for 1-2 years is the most effective means of controlling molya disease caused by Heterodera avenae in wheat. Destruction of infected/infested plants, roguing: Nematodes feed and multiply on crop root systems. With high soil temperatures, every month of a root system s life represents an additional generation, and a potential about 10-fold increase of many nematodes. Therefore, destroying root systems as soon as a crop is harvested can stop nematode reproduction and should speed their decline through normal mortality. Early detection and removal of infested plants reduces nematode spread. Antagonistic crops: A number of plants are antagonistic to nematodes. Rapeseed is a host for Pratylenchus penetrans but a green manure amendment of rapeseed tops can reduce P. penetrans populations. It may also be possible that a growing or decomposing plant encourages microbial antagonists. Certain crops like mustard, marigold and neem have chemicals or alkaloids as root exudates that repel or suppress plant parasitic nematodes. In marigold (Tagetes spp.) terthinyl and bithinyl compounds, mustard allyl isothiocyanate is present and kills nematodes. Such antagonistic plants can be grown with the main crop or included in the crop rotation. Clean planting stock: In plants propagated by vegetative means, nematodes can be eliminated by selecting the vegetative part from healthy plants. Nutrient and water management: Adequate potassium levels may enable a number of plants to tolerate large nematode populations. Ammonium sources of nitrogen have been shown to suppress a number of nematodes, including soybean cyst nematode Heterodera glycines. Soil profile manipulation: The clay content also affects nematode movement. Often, higher nematode populations and spreads are noticed in red soil and sandy soils compared to black and deep black soil. 54

80 Soil building and improvement: Deep ploughing during the onset of summer and the resulting exposure of pests to the hot sun, kills the nematodes. Application of farm yard manure or compost is also a help as these contain chemicals toxic to nematodes. In general, the addition of large amounts of organic matter to the soil reduces the population of plant-feeding nematodes. For dagger nematode control, two years of rapeseed green manure is effective. Development and use of resistant cultivars: In annual cropping systems, resistant crops can reduce nematode populations to levels non-damaging to subsequent crops, thereby enabling shortening and modification of rotations. Nematode-resistant varieties have been reported from time to time in different crops. Plant tolerance to nematode infection is highly desirable Biological control Biocontrol agents are considered the best alternative method of nematode management. Introduction: Fungi such as Paecilomyces lilacinus, Trichoderma viride, T. harzianum and Aspergillus niger have been found to suppress root knot and reniform nematodes. The bacteria Pasteuria penetrans can suppress root knot nematodes. Identified biocontrol agent can be introduced to manage the nematode population. Augmentation: This mainly involves increasing or supplemental release of natural enemy populations. These biocontrol agents are isolated from soil, mass-produced and formulated in appropriate media for better application. Conservation: The greatest success in the biological control of nematodes has been conservation and enhancement of natural antagonists present in soil. In England, the cereal cyst nematode, Heterodera avenae, is controlled successfully by growing monocultures of small grains which support high biomass of certain nematophagous fungi. Plant products as nematicides: Several plants from different botanical families, possess nematicidal or nematostatic properties. Investigations on extracts from various indigenous plants and neem products have revealed that some are effective against nematodes. Commercial formulations of these are already available. Neem-based formulations have nematicidal potential, particularly against plant parasitic nematodes. Application of neem leaves and oilseed cake to the soil can reduce nematode population densities. Seed dressing with neem seed kernel 5-10 per cent w/w has also been found to reduce nematode attack. Some commercial neem-based formulations have been effective Physical methods It is very easy to kill nematodes in the laboratory by exposure to heat, irradiation and osmotic pressure, but it is extremely difficult to use these methods in field conditions. A relatively small but important group of physical methods are typically utilized either alone or in combination with cultural and chemical management techniques, as follows: Heat: Most nematodes cannot survive at temperatures above the 50 C-60 C range and hot water treatment of planting material is highly successful in nematode control. 55

81 Nematode-infested planting material like bulbs, corms, tubers, rhizomes, roots, runners and seeds are exposed to specific temperature for a definite time period before use. Heat solarization can be an effective nematode management tactic on small land plots. Steam: Steam sterilization is followed for greenhouses and ploy houses for protected cultivation of flowers and vegetable crops. Hot water dip treatment: Hot water treatment of planting stock has been used for nematode management since at least the early 1900s. Before planting, seed material such as banana corms, onion bulbs, tubers seeds and roots of seedlings can be dipped in hot water at 50 C 55 C for 10 minutes. Table 4.2 Hot water treatment for control of nematode in planting material Planting material Nematode Temp. (ºC) Time (min.) Rice seed A.besseyi Banana sucker M.incognita R.similis Grape root stock Meloidogyne spp Citrus root stock T.semipenetrans Ginger rhizome Meloidogynespp Wheat Anguinatritici Potato Meloidogyne spp. Pratylenchuscoffeae Electricity: Passing electricity through soil before planting reduces the nematode population to some extent. It was developed in 1950 but has not been used widely. Irradiation: Irradiation kills nematodes. Cysts of G. rostochiensis exposed to 20,000 g contained only dead eggs. At 40,000g exposure, the eggs lost their content. UV light also kills nematodes. But irradiation is not feasible under field conditions. Ultrasonics: Ultrasonic waves have little effect on Heterodera spp. The use of ultrasonics is not practically feasible Chemical nematicides Although highly effective in nematode control, the use of nematicides is discouraged for several reasons. The main consideration is the cost as nematicides are generally very costly. Secondly, its use is fraught with side effects like residue problems and nematode resurgence. As such, nematicide use is recommended only when the nematode population is very high, the crop is of high valuable and quick results are warranted. Several methods can make the use of nematicides economically feasible and safer. Nematicides can broadly be grouped into two categories: fumigants and non-fumigants. Although there is much data to support the efficacy of nematicides, very little information is available for a better understanding of their precise activity in nematodes, with most information coming from known effects in insects and mammals. 56

82 Fumigants Soil fumigants are chemicals that are injected into the soil and emit toxic fumes that penetrate air spaces in the soil and kill microorganisms. Fumigants must be sealed into the soil with water or a plastic sheet to ensure a lethal concentration and exposure time. As fumigants are harmful to all living plants, a certain amount of time (from two weeks to two months) must pass between treatment and planting to avoid crop damage. Several nonfumigant nematicides are available for different vegetable crops and are usually systemic compounds that may also be effective in insect control. Most pre-plant fumigants such as dichloropropene (Telone II), chloropicrin, or metam-sodium (Busan, Nemasol and Vapam), can be used for nematode control. The ideal fumigation time is when soil temperatures at a 15 cm depth, range between 20 o C and 30 o C, and the soil has a moderate amount of moisture. The fall period months are usually the best time for fumigation. Pre-plant fumigation in the spring should be done CAUTIOUSLY as some fumigants may linger in cool and wet soils and increase the possibility of injury to young plants. The field must be prepared for soil fumigation before planting a vegetable crop. The soil should contain little or no crop debris, be free of clods and the moisture level must be adequate to support seed germination. If the soil moisture level is low, the field should be irrigated. If the field is not prepared properly, soil fumigation will be not effective due to lack of penetration of all soil particles by the gaseous fumigant. Soil fumigants are injected to a depth of 15 to 20 cm. Immediately after application, the soil should be dragged and rolled to delay fumigant loss. Metam-sodium is soluble in water and can be injected and applied using irrigation systems such as a solid set sprinkler or drip/trickle. Metam-sodium must be injected for the entire time that the field is irrigated. Rinse the irrigation system with clean water only long enough to clear the system. Too much rinsing or heavy rainfall within 24 hours of application will reduce the efficacy of the treatment. The following multipurpose soil fumigants should be used to provide disease and nematode control: Hologented hydrocarbon- D.D., EDB (Ethylene Di Bromide), MBr (Methyl Bromide), Chlorophicrine,DBCP (Nemagon) MIT- Dazomet, Metam sodium 57

83 Table 4.3 Nematicides available in world markets Chemical name Trade name Formulation Fumigants Methyl bromide Dowfume Gas 1,3 dichloropropene Telone/DD-95 Liquid Ethylene dibromide Dowfume W-85 Liquid Metam-sodium Vapam Liquid Dazomet Basamid Dust (prill) Methyl isothiocyanate Di-Trapex Liquid Chloropicrin Larvacide Liquid Organophosphates Thionazin Nemafos Granular or emulsifiable liquid Ethoprophos Mocap Granular or emulsifiable liquid Fenamiphos Nemacur Granular or emulsifiable liquid Fensulfothion Dasanit Granular Terbufos Counter Granular Isazofos Miral Granular or emulsifiable liquid Ebufos Rugby Granular or emulsifiable liquid 58

84 Table 4.4 Recommended nematicidal dosages and treatments for some important crops Crop Nematode pest Nematicide Application rate (kg a.i./ha) Application techniques Potato Globodera spp. Aldicarb Incorporated in row Tomato, cucurbits Citrus Oxamyl Carbofuran Meloidogyne spp. Aldicarb 3.36 Incorporated in 30-cm bands Tylenchulus semipenetrans Grape Meloidogyne spp. Fenamiphos (e.c. formulation) Banana Ethoprophos Incorporated in bands OxamyI Incorporated in bands Fenamiphos Incorporated in bands Dazomet g/m 2 Incorporated in bands and irrigated Time interval before planting Fenamiphos Annual treatment; applied along drip-line Aldicarb Annual treatment; applied along drip-line 10.0 In bands for nursery use Xiphinema index Aldicarb 5-10 In bands for nursery use Radopholus similis and/or Carbofuran 2-4 ga.i. per plant Applied around plant, 2-3 times per year Helicotylenchus multicinctus and/or Ethoprophos 2-4 ga.i. per plant Applied around plant, 2-3 times per year Pratylenchus spp. and/or Fenamiphos 2-4 ga.i. per plant Applied around plant, 2-3 times per year Meloidogyne spp. Isazofos 2-4 ga.i. per plant Applied around plant, 2-3 times per year Ebufos 2-4 ga.i. per plant Applied around plant, 2-3 times per year Non-fumigants Several non-fumigant nematicides can be used on selected crops. These nematicides do not volatilize in the soil like fumigants. Therefore, soil temperatures and moisture requirements are not as critical, but always check the label before using any of these chemicals. Non- fumigants i. Organophosphates Common name Ethoprop Fenamiphos Phorate Thionazin Trade name Mocap Namacur Thimet Nemaphos 59

85 ii. Carbamates Common name Trade name Aldicarb Temic Carbofuran Furadan Metham sodium Vapam Oxamyl Vydate Types of treatment i. Before sowing: soil application of Carbofuran 1-3 kg/ha (3-6 g/m²). ii. At the time of sowing: Seed/seedling treatment before sowing. a. Seed dressing/treatment: Carbofuran 3G. b. Seed soaking: Carbosulfan 25 EC, monocrotophos 36 SL, dimethoate 30 EC can be 0.05 per cent to 0.2 per cent. The duration of soaking depends on the nature of the crop and varies between 4-12 hours. iii. Seedling dip treatment: In transplantable crops like tomato, chilli and brinjal, seedling bair root dip treatment can be 0.05 per cent-0.02 per cent. iv. Foliar treatment: Systematic compounds such as carbosulfan, monocrotophos can be used to control the nematode ppm (0.12 per cent) at an interval of 15 days. Advantage of using these chemicals Also effective against some insects Effective at low dosages Easy to handle and apply Less phototoxic Systemic in nature Economizing namaticide use Seedling bare root deep treatment Seed treatment (coating or dipping) Nursery bed treatment Row and spot application in wider spaced crops Systemics These are non-fumigant nematicides generally used for soil application, which enter the plant systemically and provide protection against nematodes. When systemic nematicides are applied to moist soil, the active ingredients are rapidly released (even by the granules) and absorbed by plant roots. The amount of toxicant absorbed is related to the number of roots in contact with the toxicant in soil solution. Systemic nematicides, when absorbed by roots have been shown to be more protective in nature, to reduce nematode invasion, and in some cases to slow nematode development. However, in most cases, the main effect of systemic nematicides appears to be in soil rather than by systemic action in the plant. Temik and Vydate, although readily taken up by plants, are believed to act as nematicides mainly in the soil solution by interfering with the locomotion and feeding of newly hatched nematode larvae and causing their death by starvation or poisoning. Thus, a good distribution of nematicide in the rooting zone is essential when hatched larvae are moving towards roots. 60

86 4.6 Conclusion Plant-parasitic nematodes must be addressed in crop production and IPM systems if sustainable agriculture is to meet world demands for increasing food and fibre production. Annual crop losses worldwide due to nematode damage have been estimated to be 12.3 per cent of total production on average, amounting to some $77 million annually. Nematodes can cause economic damage of between 40 to 50 per cent of crop value, and sometimes even result in a complete crop loss. The main nematode problems throughout the Asia- Pacific region are caused by root knot nematodes, Meloidogyne spp. Other nematodes include Rotylenchulus reniformis, Radopholus similis, Tylenchulus semipenetrans, Helicotylenchus multicinctus, Pratylenchus spp. and Ditylenchus dipsaci, and cyst nematodes (Globodera/Heterodera spp.). Integrated nematode pest management is a relatively recent development and involves the development and deployment of nematode control strategies and measures with favourable socioeconomic and environmental consequences. Strategies and measures for controlling nematodes include the use of resistant varieties, cultural practices, rotation, biological control and physical treatment such as solarization. The following measures are recommended for effective integrated nematode pest management in affected countries: Nursery bed treatment with 0.3 g a.i./m 2 followed by field application of 1 kg a.i./ha, 40 days after transplanting in endemic spots in fields for management of root knot nematode (Meloidogyne graminicola) and rice root nematode (Hirschmanniella oryzae) in rice. Hot water treatment of rice seeds for 10 minutes at 50 C to 55 C, followed by foliar spray with carbosulfan ( per cent, 40 days after transplanting to reduce infestation of white-tip nematode (Aphelenchoides besseyi). Soil solarization of nursery beds by a transparent polythene sheet (25μm -50μm) for 15 days during summer, and application of 0.3 g a.i./m 2 before sowing, followed by root dip treatment of transplantable seedlings of vegetable crops with carbosulfan ( ppm before transplanting to main field against root knot nematode disease of tomato, brinjal and chilli. Deep summer ploughing in areas with a hot and dry summer reduces infestation of root-knot and cereal cyst nematodes. Solarization of nematode-infested field + seed dressing of direct-seeded crops with carbosulfan (25 3 per cent a.i. (w/w) in mung bean, cowpea, black gram, okra, cucurbits and others, reduces attacks of root knot, reniform and lesion nematodes. Use of bioagents, namely Pseudomonas fluorescens/trichoderma 10 g/kg seed has been found effective against root knot nematodes and pigeonpea cyst nematode (Heterodera cajani) infecting pulse crops. Seed treatment of chickpea with neem-seed kernel powder or Trichoderma 10 g/kg seed has been recommended for effective management of Pratylenchus thornei. Use of organic amendments, including neem and castor 1 ton/ha has been found to reduce root knot nematode damage in vegetables and groundnut. Combinations with seed treatment of carbosulfan (25 3 per cent a.i. (w/w) results in enhanced efficacy in reducing nematode populations and boosting yield significantly. 61

87 Farmers advised to sow groundnut with castor as an inter-crop (row ratio 2:1) along with soil application of 1.0 kg a.i./ha to reduce the population of root knot nematodes infecting groundnut. Seed-dressing treatment with plant growth promoting rhizobacteria (PGPR) and soil application of 1.0 kg a.i./ha has been found effective against root-knot nematode (Meloidogyne incognita) infecting cotton. Paring and hot water treatment of banana suckers at 55 C for 20 minutes combined with neem-cake 1 kg/plant and 16.6 g/plant in the pit before planting, was effective against nematode disease complex of banana. 62

88 5 Integrated Rodent Pest Management 5.1 Introduction Rodents are a unique order Rodentia in the mammalian class and their peculiarity goes far beyond the fact that the order consist of 2,277 of the 5,419 mammalian species. The order rodentia comprises 34 families that include 389 genera throughout the world. Rodents are the most serious and important vertebrate crop pests, inflicting damage from sowing onwards until harvesting, storage, distribution and actual consumption of the produce, besides acting as a reservoir of major diseases such as plague, murine typhus, leptospirosis and salmonellosis. The order Rodentia is named thus because of their gnawing teeth (Rodere = to gnaw; dent = teeth). Rodents have only a single pair of incisors, three pairs of molar in upper and lower jaws, and no canines. Rodents are segregated into different groups that include porcupines, squirrels, voles, marmots, gerbils, mice, moles and rats but have a common characteristic of gnawing teeth. Rodent management measures often ignore the types of species. A basic principle for effective rodent management is a species approach. Although there are thousands of rodent species, no more than three to five are a cause for major concern at any given area and time. Hence, the rodent species in a given area need to be known for planning control options. 5.2 Identification of different rodent pest species Group I. Porcupine Indian crested porcupine, Hystrix indica: A larger rodent species, the porcupine s body is covered with long tapering quills having alternate black and white bands. The quills are a self-defense mechanism. With long crest bristles from the forehead on the dorsal side and a short tail covered with short white quills, the adult porcupine weighs between 10 and 18 kg. It is nocturnal and terrestrial, living in rock caves or in burrows 8-20 m long and having wide chambers, in areas with soft soil. Usually living in family groups, porcupines cause huge damage to sweet potato, potato, beetroot, onion and carrot crop fields. 63

89 Figure 5.1 Indian crested porcupine Group II. Squirrel a. The five striped squirrel, Funambulus pennant: The squirrel is medium-sized, weighs about 90 g and has a bushy tail. The dorsal side is greyish brown with five distinct white stripes, separated by four off-white bands. The tail is white with a blackhued middle section and white-hued tip. The body is covered with soft fur. Squirrels live close to human habitations, orchards, gardens, parks and in areas with a number of trees. The peak breeding period is from February to September. Squirrels cause severe damage to rice nurseries, maize, fruits and vegetables. b. Three striped squirrel, Funambulus palmarum: This has three distinct white stripes, a bushy tail equal to the combined length of the head and body, weighs g, is diurnal and arboreal (living/making nests on tree trunks/leaves). It infests horticultural and plantation crops and is a serious pest in cocoa, cardamom, coconut, coffee, arecanut and fruit orchards. Figure 5.2a Five-striped squirrel Figure 5.2b Three-striped squirrel 64

90 5.2.3 Group III. Gerbil The Indian gerbil, Tatera indica: Light brown in colour, varying from sandy brown to grey on the dorsal side and pure to off-white ventrally, this has white feet, large beautiful eyes and weighs between 100 and 150 g for males and g for females. It is also regarded as a reservoir of the plague bacillus. T.indica excavates simple burrows, preferring to build a burrow at higher levels in irrigated crop fields. The burrows are easy to spot because of the beaten paths or runways leading from one opening to another. Gerbils are nocturnal and destructive to almost all cultivated crops at every stage. Figure 5.3a Indian Gerbil, Tatera indica Figure 5.3b Burrows of T. indica Group IV. Bandicoot a. Lesser bandicoot, Bandicota bengalensis: The lesser bandicoot rat, B. bengalensis is the predominant rodent pest species found in crop fields and urban areas. It is a robust rodent with a body weight of g, a rounded head and a broad muzzle. The tail is shorter than the combined head and body length, and the dorsum is coloured brown and has coarse hair. These are found in various ecological conditions. Bandicoots are nocturnal and fossorial, living in self-constructed burrows and causing extensive damage to agriculture crops. Figure 5.4a Lesser bandicoot rat Figure 5.4b Burrows of lesser bandicoot rat b. Larger bandicoot, Bandicota indica: It is the largest commensal rodent with a body weight of 500-1, 500 g. The body is robust with rounded ears and a short, broad muzzle. It is covered with piles of long hairs which stand erect on being excited. The tail is shorter than the body and is naked with short hairs throughout its length. It is 65

91 omnivorous and nocturnal, living in villages, burrowing the mud walls of huts, and in backyards and gardens. It also consumes soil invertebrates like earthworm and insects. Figure 5.5 Larger bandicoot Group V. Rat The three commensal rodents include the Brown or Norway rat, the Black or Roof rat and the House mouse. a. Roof rat: Roof rats (Rattus rattus) are small sized with a body weight of g. Their bicoloured and ringed tail is longer than the combined length of the head and body. Living in the upper floor of sheds but sometimes seen in sewers, the roof rat is also called black rat, house rat or ship rat. It is nocturnal and has a traveling range of 30 m. b. Norway rat: The Norway rat (Rattus norvegicus) is medium-sized with a thick body and weighs around 120 g. Aggressive and burrowing in nature, it is found around dumps, sewers, buildings and close to food and water. The Norway rat is also called sewer rat, brown rat, common rat or wharf rat and has a running range of 30 to 50 m. It can eat anything, but particularly likes poultry, fish, cereal, fruits and vegetables. c. Soft furred field rat, Millardia meltada: A small rodent weighing g with a soft furry body, a light grey dorsumand bicoloured tail equal to or shorter than the combined head and body length. Found in semi-arid areas with vegetation, it lives in irrigated fields and grasslands. Nocturnal, fossorial and living in a small, simple burrow, it is a pest for rice, pulses, cotton and groundnut crops. This species is mainly associated with B. bengalensis. 66

92 Figure 5.6a House rat Figure 5.6b Norway rat/ sewage rat Figure 5.6c Field rat Group VI. Mice a. House mouse: The house mouse (Mus musculus) is small in size with a body weight of about 15 g and a slightly pointed nose and hairless tail with scale rings. Its tricoloured tail is longer than the length of the head and body. It makes its nest in walls, cabinets, old furniture and godowns and has a travelling range of between 3 and 10 m. b. Indian field mouse, Mus booduga: A tiny mouse weighing about g, with a slender, short and naked body and a bicoloured tail. It is nocturnal and fossorial and found in crop fields, especially irrigated. Individually, it is a minor pest, but in larger numbers, can cause much damage. Figure 5.7a House mouse Figure. 5.7b Field mouse 5.3 Rodent problems in different sectors Agriculture Agricultural plots in developing countries of the Asia-Pacific region are generally small and dispersed and are intermixed with fallow land, providing fertile breeding grounds for rodents in the lean cropping season or when the crop is not at a suitable stage for rodent infestation. Rodents also contribute to contamination and deterioration of consumable items and enhance human susceptibility to fungal and bacterial infestations. Rodents affect almost all field crops at almost all stages of the crop from sowing to harvesting. The nature of damage and estimation protocols for identified crops are as follows: a. Rice: In Asia, the pre-harvest loss of rice, Oryza sativa due to rodents is estimated to be 5 per cent of production, or approximately 30 million tons (i.e. enough rice to feed 180 million people for a year). The post-harvest losses are likely to be similar. 67

93 b. Wheat: Tillers are damaged at a height of cm above ground level as with rice. In the process of eating the grains, the straws are broken into small pieces and strewn all over the area. c. Sugarcane: Rodents damage the sugarcane crop by eating the buds of seed sugarcane pieces, apical growing points of young and mature stalks and the millable part of the cane. In addition, their burrowing habits damage the root system, leading to the total drying of the cane. d. Groundnut: The field symptoms of rodent damage are the presence of loose soil heaps with wilting and shells of immature groundnut pods strewn in the attacked area. In red soils, groundnut crops are more susceptible to rodent infestation and damage Horticulture a. Coconut: Typical rodent damage to tender coconut is an about 5 cm small hole near the perianth region. After gnawing the husk, the rodent eats the inner content and the damaged nut may fall to the ground in two to six days. b. Cocoa: While squirrels damage the cocoa pod in the centre, rats cause damage near the peduncle. The intensity of damage to cocoa by rats and squirrels is always on the higher side. c. Cardamom: Rodents damage the capsules at the base of the clump. Damage coincides with crop maturity. d. Oil palm: Rodents damage oil palm at the seedling, flowering and maturity stages. The damage is more to seedlings and young pods Storage loss The estimated loss of stored commodities due to commensal rodents in tropical and subtropical areas ranged from 2 to 15 per cent. According to an estimate by the World Health Organization (WHO), rodents in India s metropolis of Mumbai damage enough foodgrain to feed 90,000 people every year. Various reports also indicate a wide range of post-harvest losses varying from 2.5 to 30 per cent in different climatic conditions of the world. 68

94 Table 5.1 Estimated losses caused by rodents in major agricultural crops in Asia Crop Country (State) % of damage Source Rice Bangladesh >50 Singleton (2003) China 5-10 Indonesia Lao PDR Malaysia 5 Myanmar 5-40 Philippines >20 Thailand 6-7 Viet Nam Upland > ha India (Madhya Pradesh State) 6 Patel et al. (1992) India (Meghalaya State) 12.5 Singh et al. (1994) India (Andhra Pradesh State) Rangareddy (1994) India (Karnataka State) 2-44 Chakravarthy et al. (1992) India (Tamil Nadu State) 4-30 Neelanarayanan (2008) Sakthivel & Neelanarayanan (2014) Wheat India (Himachal Pradesh State) 7 Sheikher and Jain (1991) India (Punjab State) 3-12 Ahmad and Parshad (2001) India (Uttar Pradesh State) 8-10 Rana et al. (1994) India (Rajasthan State) Jain et al. (1993) Sugarcane Thailand 5.3 Flotow (1980) Pakistan 11 Beg et al. (1979) Pakistan (Punjab Province) 7.2 Fulk et al. (1980) Pakistan (Sindh Province) 4.2 Fulk et al. (1980) India (Punjab) 9% Ahmad and Parshad (1987) Kocher and Kaur (2007) Singla and Parshad (2010) India (Uttar Pradesh) 7 Singh et al. (1988) India (Tamil Nadu) 8-10 Saravanan and Kanakasabai (1999) Black gram India (Tamil Nadu) 3-5 Sakthivel & Neelanarayanan (2015) Green gram India (Tamil Nadu) 60 Neelanarayanan (2008) Coconut India (Tamil Nadu) 5-11 Dept. of Agriculture Soybean India (Tamil Nadu) 43 Dept. of Agriculture Ground nut India (Tamil Nadu) Neelanarayanan et al. (2008) Oil palm India (Andaman and Nicobar Islands) Subiah (1983) India (Tamil Nadu) 11 Dept. of Agriculture Sesamum India (Tamil Nadu) 11 Dept. of Agriculture Cumin India (Rajasthan) 10 Chaudhary & Tripathi (2008) Pineapple India (Tamil Nadu) 44 Dept. of Agriculture Cotton India (Tamil Nadu) 55 Neelanarayanan (2008) 69

95 Figure 5.8 Rodent damages in field crops and storage a. Rat damage in paddy (tiller cut at 45 o ) b. Rodent damage in wheat crop c. Rodent damage in sugarcane d. Rodent damage in groundnut e. Rodent damage in Black gram f. Rodent damage in cotton 70

96 Figure 5.9 Rodent damage in horticultural crops and poultry a. Rat damage in coconut b. Rodent damage in cocoa c. Rodent damage in tomato d. Rodent damage in pineapple e. Rodent damage in watermelon f. Rodent damage in orange g. Rodent damage in grapes h. Rodent damage in poultry 71

97 5.4 Integrated rodent management strategies Although rodent control in crop fields has been practised for centuries, the problem is still acute because of the haphazard strategy, aimed at removing pests during outbreaks. It is important to recognize that rodent control is an ecological operation involving the regulation of populations and not the destruction of individuals. Rat control can be best achieved by being aware of the rat s basic needs such as food and shelter and then limiting the factors that favour rats. Several cultural practices can be used to limit rat population growth Harbourage reduction/habitat management Garbage, junk and other hiding and nesting material provide harbourage to rodents in stores and godowns. The periodic removal of rubbish and maintenance of good hygiene/sanitation discourage rodents. It also means removing spilled grains and food scraps left over from feeding pets or domesticated animals. Deep ploughing and removal of weeds, both within the crop and along the bunds, has an important limiting effect on the rat population. Clearance of weed and bush overgrowth around rice fields also limits rodent numbers by reducing the source of food and shelter in lean periods and increasing their exposure to predators. Reduce the size and number of bunds to limit burrowing sites and places for weeds to grow. Synchronized planting of rice with varieties having the same duration, over wider areas, acts as natural check to rat population growth as rat breeding is linked with the growth phases of the rice crop. The availability of the rice crop in its reproductive stage for longer periods will lead to extended rat breeding and very high levels of rat infestation. Proper water management in rice fields may prevent rodent damage to germinating seeds in nursery. Complete removal or destruction of rice stubbles after the harvest limits the rodent population, which otherwise provides food during the lean period Rodent-proofing Rodent-proofing of storage structures is the first line of defence. Improvements to reduce losses in traditional storage structures involve adoption of rat-proof techniques such as: a. A concrete or reinforced brick floor as the base for straw-roped structures. b. A wooden platform with metallic cones (indoor) or a masonary platform with GI sheet roofing (outdoors) for bamboo storage structures. c. Nailing a metallic sheet to the bottom of wooden storage structures. d. Improved storage structures like metallic drums Mechanical control a. Trapping: The most used method of mechanical control is trapping. Locally available traps should be placed on rodent paths, their success depending on proper placement and selection of bait. Different types of rodent traps are available, both commercially (box trap, Sharman trap, metal snap trap and sticky/glue traps) and traditional (Tanjore kitty and Butta trap). Most local traps/snap traps are made of small bamboo sticks and are effective in controlling field rodents. 72

98 Figure 5.10a Tanjore kitty/trap Figure 5.10b Butta trap/palmyrah trap Figure 5.10c Multi-catch trap b. Burrow smoking: Most field rodents live in burrows and the use of smoke is an age-old control measure. A Burrow Fumigatoris a simple metal container in which straw is burned to generate smoke. Air is pumped through one end using a hand operated pumping machine and the smoke ejected from the other end can be directed through pipes into the burrows Repellants a. Ultrasonic devices: Rodents hear at frequencies above 20 khz and extending well into the ultrasonic range. Ultrasonic sound devices have been used to repel rodents, although, so far no convincing evidence has been found of their effectiveness due to rodent acclimatization to the sound over time. b. Chemical repellents: There is no chemical that both repels rodents and is non-toxic to humans. Field rodents often damage rodent-repellent cables in telecommunication networks. Although pheromones seem to be promising in regulating rodent reproduction behaviour and masking bait shyness, such pheromones are still to be scientifically identified and isolated Chemical control The control of rodents with rodenticides is the most common practice. It is better to undertake rodent control using poison baiting during the lean periods when the rodent population is at its minimum. The two most used groups of rodenticides are: 1. Acute rodenticides like aluminium phosphide and zinc phosphide 2. Chronic rodenticides like Warfarin and Bromadiolone Among anticoagulants, single dose of anticoagulants (bromadiolone, broadifacoum and flocoumafen) are more effective than multi-dose anticoagulants and are widely used. a. Acute rodenticides: Acute rodenticides are fast acting, bringing mortality within 24 hours usually. Two inorganic chemicals in this category are barium corbanate and zinc phosphide with the latter being used the most. Zinc phosphide: Zinc phosphide is a greyish-black powder with a smell of garlic and produced by the direct combination of zinc and phosphorus. It is the most used acute rodenticide in the world. It is insoluble in water and alcohol, stable when dry, but 73

99 decomposes gradually in moist air. It is decomposed quickly by acids, leading to the production of the lethal gas phosphine, which is very toxic to mammals. The acute oral toxicity of zinc phosphide to rodents is as follows: Tatera indica (35mg/kg), Rattus rattus (40.1 mg/kg), Bandicota bengalensis (25.0 mg/kg) and Mus musculus (250 mg/kg). This poison is widely used against field rat and mouse infestations. Baits with 2 per cent, are generally recommended. Respiratory poisons: Aluminium phosphide pellets of 0.6 g are recommended for rodent burrow 2 pellets per burrow. This is a restricted rodenticide to be used under the supervision of technically competent persons. The burrows of B. bengalensis can be effectively treated with this fumigant. Rodent burrows are fumigated with aluminium 3 g per burrow and the burrows must be closed with wet mud after the application. As aluminium phosphide is highly toxic, this should be done under technical supervision. b. Slow acting rodenticides (Anticoagulants): Slow-acting rodenticides all belong to the category of anticoagulants, which act primarily by preventing blood coagulation. Anticoagulants introduced in the initial years are first generation anticoagulants. However, with the advent of resistance among residual populations, more potent anticoagulants have been developed. These are second-generation anticoagulants with the added advantage of effective kill of even resistant populations, with a reduced quantity of poison baits. Warfarin: A first-generation anticoagulant that kills rodents after uptake of 4-5 daily doses of 0.2 mg/kg per day. Its acute toxicity is 173 mg/kg. It has been extensively used for controlling rodents in storage. It is recommended at per cent a.i. in cereal baits and in liquid bait. However, warfarin is not commonly available in the market at present. Bromadiolone: A second-generation anticoagulant that kills resistant rodents. The acute oral toxicity is 3-5 mg/kg. Single feeding of baits also kills rodent population (40-60 per cent three days after application. Hence, it is recommended as a 'Pulsed baiting' technique. It is formulated as concentrate powder (0.25 per cent) and as ready-to-use bait (0.005 per cent). It is recommended at per cent a.i. in solid bait by mixing 1 part of the concentrate in 49 parts of bait material for controlling rodents in storage and agricultural situations. Application in 10 paper packets gives significant results in field conditions. In domestic situations, usage in simple bait stations yields good results. The ready-to-use cake is coated with a thin layer of wax to protect the bait from the weather. The cakes are recommended for use in inaccessible situations in field conditions. c. Bait preparation: To prepare 500 g solid bait, take 450 g (four tea cups) of locally preferred, crushed cereal bait, 15 g (three teaspoons) of sugar and 10 g (two teaspoons) of oil. Mix these thoroughly and add 25 g (five teaspoons) of anticoagulant. Mix thoroughly. Placement of bait burrow baiting: Identify live burrows and place 10 g of bromadiolone (0.005 per cent) bait (96 parts of rice brokens + 2 parts of edible oil + 2 parts of bromadiolone concentrate) inside the burrow. Station baiting: A quantity of g prepared cereal/ready to use bait is placed in bait stations and kept at selected points. 74

100 Table 5.2 Action plan for rodent control measures in field Day 1 Day 3 Day 4 Day 5 Day 14 Identify live burrows and place 20 g of pre-bait material inside the burrow and leave the bait for 2-3 days. Place 10 g zinc phosphide/15 g bromadiolone poison bait inside the burrow. Collect and bury dead rats, if any, and close all burrows. Eliminate the residual population by trapping or burrow fumigation with burrow fumigator in the case of zinc phosphide poisoning. Treat opened burrows with aluminum phosphide 2 pellets per burrow. Eliminate residual population by trapping or burrow fumigation in the case of bromadioline poisoning Biological control Role of predators: The cat, spotted owlet and barn owl are predominant rodent predators inside the house and in the field, respectively. Rodents are prey for snakes such as cobra, russel viper (75 per cent), krait (29 per cent) and scaled viper (22 per cent). However, snakes have a feeding rate of only one rodent in three days. Among predators, the barn owl can consume up to six rodents per night with an average of 1.58 rodents a day. To increase the barn owl population in fields, an artificial nest box (90 x 45 x 50 cm) and T- shaped owl perches can be used. The T-shaped owl perch is being popularized in cereal crops as an IPM practice. However, its use is not desirable after the flowering stage of the crop as grainivorous birds utilize the perches for feeding on the crop. Keeping raptors and owls in nesting boxes is a practice followed in countries like Indonesia, Kenya, Malaysia and Tanzania. It has been reported that the erection of one barn owl nest box per 10 ha is sufficient to reduce crop damage by rodents in rice fields in Malaysia. 5.5 Conclusion No single rodent control method suits all situations and even under ideal conditions, most control methods have variable results. This makes it imperative to use several rodent control approaches. Modern pest management is essentially an application of different control measures in an integrated manner in keeping with biotic and abiotic factors. Like other pest control measures, rodent control can rely on physical, mechanical, biological and chemical methods. Poison-baiting, fumigation and trapping techniques sometimes produce good results. However, effective and long-lasting results require different methods in sequence or in combination. Decisions on methods are, however, made on the basis of effectiveness, cost, potential side effects and cultural acceptability. 75

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102 6 Integrated Weed Management 6.1 Introduction Weeds are unwanted plants and can be a serious threat to primary production and biodiversity, reducing farm and forest productivity, displacing native species and contributing significantly to land and water degradation. Weed invasion is ranked second only to habitat loss as a cause of biodiversity decline. Weed management is an important component of plant protection that improves the production potential of crops. It includes management of the weeds so that the crop sustains its production potential without being harmed by weeds. There are mechanical, cultural and chemical methods of weed management. Biological control methods are still in their early stages. Herbicides are an important and much-used weed management method and new weed management tools have been designed. 6.2 Weed characteristics and classification Sound weed management strategies depend on correct identification of weed plants. Many classifications are used, but for practical purposes and easy identification, weeds are generally classified by morphological characteristics as grasses, sedges, and broad leaves. Some times ferns and algae are also included in this classification Grasses (family-poaceae or Gramineae) Important morphological characteristics: Round, cylindrical stem called culm. Stem has nodes at regular intervals from which leaves arise. Portion between nodes is called inter-node and is usually hollow. Leaves are aligned up and down the stem, alternately in two rows. The upper portion of a leaf is called leaf blade and is parallel-veined. The lower portion of a leaf is called leaf sheath, usually overlapping to form a tube around the stem. At the junction of the leaf blade and leaf sheath, there is a papery membrane called ligule. The primary root has a shorter duration and is soon replaced by adventitious roots, which form the fibrous root system, and sometimes a bundle of fleshy roots. 77

103 The inflorescence contains a pistil, three stamens enclosed by a pair of unequal bracts. The lower and larger is called lemma, and the upper and smaller is called palea. Florets comprising the flower, lemma and palea are arranged in spikelets, each having a central axis, a pair of bracts or glumes at the base, and a single or several florets above these. The fruit, called grain or caryopsis, has a single seed and the fruit coat adheres permanently to the seed. Examples: Cynodon dactylon, Echinochloa colona, Digitaria sanguinalis Sedges (family-cyperaceae) Similar to grasses, but with the following distinguishing features: Solid triangular stem. Three-ranked leaves with each new leaf arising one-third of the way around the stem from the leaf below. Leaf sheath fused to form a tube around the stem. Absence of ligule. Flowers are not enclosed by a pair of bracts but are usually in the axis of a single bract. Examples: Cyperus rotundus, Cyperus iria, Cyperus difformis, Fimbristylis littoralis Broad-leaves All dicotyledonous and some monocotyledonous plants belong to this category. Some important characteristics of this group: Usually wider leaves that are flatter and bigger than those of grasses and sedges and with different shapes. Venation in broad-leaved plants is mostly of the reticulate type. Primary roots often persist and become strong tap roots, with smaller secondary roots. Examples: Celosia argentea, Amaranthus viridis, Eclipta alba, Commelina benghalensis, Monochoria vaginalis, Ipomoea spp Parasitic weeds Tall, bright green stem and leaves; hemi-parasite; usually white flowers. In case of S. densiflora, the plant is robust, less branched and with white flowers. Examples: Striga lutea and S. densiflora. 78

104 Figure 6.1a Grass-Cynodon dactylon Figure 6.1b Grass-Echinochloa colona Figure 6.1c Grass-Digitaria sanguinalis Figure 6.2 Sedge-Cyperus rotundus Figure 6.3a Broad leaf-celosia argentea Figure 6.3b Broad leaf-amaranthus viridis 79

105 Figure 6.3c Broad leaf-eclipta alba Figure 6.3d Broad leaf- Commelina bengalensis Figure 6.3e Broad leaf- Monochoria vaginalis Figure 6.3f Broad leaf- Ipomoea aquatica Figure 6.4a Parasitic weed-striga lutea Figure 6.4b Parasitic weed-cuscuta spp. 6.3 Impact of weeds on crops Weeds are an important pest group affecting farming in a variety of ways. Besides competing with crops for inputs, weeds also affect human health with some being poisonous. Weeds have the following impact: Compete with crops for moisture, light and nutrients. Yield losses may be small with only a few weeds, but a heavy infestation can cause complete crop failure. Weed seeds contaminate grain and the removal of weed seeds from grain for export is expensive. Unpalatable pasture weeds reduce forage quality. Many weeds cause hay fever by reducing pollen. Aesthetically unpleasing and can lower property values temporarily. 80

106 Harbour inoculum of insects and crop diseases and in many cases act as alternate hosts. Cause environmental damage and threaten natural resource diversity. Introduced weeds can displace native vegetation, including rare and endangered species. Weed problems in commercial crops vary with agroecological conditions and management levels. Climatic, edaphic and biotic factors determine the composition of weed flora to a large extent. Weed species also differ in their proportion from crop to crop, field to field and the crop cultivation season. Critical period of crop-weed competition: A fundamental principle of plant competition is that early occupants of the soil tend to exclude those that follow later. This principle is used in practical weed control. Weeds accumulate dry matter faster than crop plants. Thus, the duration of weed infestation and the time of weed removal have a significant influence on growth and yield. However, the nature of competition between the weed and crop depends on many factors including type, diversity and extent of the crop and weed species. In crops like sugarcane, cotton, jute and tobacco, frequent irrigation, heavy fertilization and wider row spacing, results in rank growth of weeds, smothering the crop and causing heavy yield loss. Depending on these factors, the reduction in the economic yield of major commercial crops is as follows: Sugarcane: Cotton: Jute: Potato: Tobacco: Up to 90 days after planting (60-80 per cent loss) days after sowing (40-50 per cent loss) days after sowing (50-60 per cent loss) days after sowing (30-60 per cent loss) Up to 70 days after planting (40-60 per cent loss) Good crop husbandry: There is no substitute for good crop husbandry methods as a weed control method. These are also referred to as ecological control methods or good agronomic practices. Good agronomic practices are modified and improved on the basis of factors such as agroclimatic conditions, cropping patterns, magnitude of weed menace and the feasibility of control methods. These proven improved weed management methods or techniques recommended for field application are usually referred to as advanced agronomic practices for weed management. Agronomic practices weaken weed growth through crop competition and indirectly help in improving the efficacy of other weed control methods. 6.4 Integrated weed management Integrated weed management (IWM) may be defined as the combination of two or more weed control methods at a low input level to reduce weed competition in a cropping system. The IWM approach is a combination of mechanical, cultural, biological and chemical practices in a planned sequence so as not to affect the ecosystem. IWM uses a variety of technologies in a single weed management system, with the objective of producing optimum crop yield at a minimum cost, taking into consideration ecological and socioeconomic constraints of the agroecosystem. FAO has defined IWM as the use of all economically, ecologically and toxicologically justifiable methods to keep harmful organisms below the threshold level of economic damage, keeping in the foreground, the conscious employment of natural limiting factors. 81

107 Integrated weed management can be implemented as a preventive or a post-emergence management strategy Preventive weed control This includes all measures to prevent the introduction and/or establishment of weeds. A weed control programme cannot be successful if adequate preventive measures are not taken to reduce weed infestation. Effective and economic weed management requires longterm planning. The following preventive control measures should be adopted wherever possible: 1. Avoid using crop seeds infested with weed seeds. 2. Avoid using feed material containing weed seeds. 3. Avoid adding weeds to manure pits. 4. Clean farm machinery thoroughly before moving it to another field. This is particularly important for seed drills. 5. Avoid use of gravel sand and soil from weed-infested area. 6. Inspect nursery stock for the presence of weed seedlings, tubers and rhizomes. 7. Keep irrigation channels, fence lines and uncropped areas clean. 8. Inspect the farm frequently for strange-looking weed seedlings. Destroy such new weed patches by digging deep and burning the weed along with the roots. Sterilize the spot with a suitable chemical. 9. Quarantine regulations need to be adhered strictly to prevent the entry of invasive alien weed species Weed management strategies It is very difficult to control weeds through preventive strategies alone. Eradicative strategies are also needed, which normally aim at total eradication. It is normally followed in greenhouse conditions and for high-value crops. Weed management strategies usually aim to reduce and not eliminate the infestation. IWM strategies seldom aim to kill weeds but severely restrict their growth Mechanical weed control Mechanical or physical methods of weed control include tillage, hoeing, hand weeding, digging, cheeling, sickling, mowing, burning, flooding and mulching. Tillage: Tillage uproots weeds from the soil, or may weaken weed plants through root injury and stem pruning, and reducing competitiveness or regenerative capacity. Tillage also buries weeds. Both top and underground growth of perennials is destroyed by tillage. Hoeing: This centuries-old method is still highly effective and economical, supplementing the cultivator in row crops. Particularly effective on annuals and biennials as weed growth can be completely destroyed. Hand weeding: The oldest weed conrol method involves physical removal of weeds by hand or with the help of small mechanical implements and is still a practical and efficient method. Digging: Digging is very useful for perennial weeds as it removes the underground propagating parts of the weed from the deeper soil layer. 82

108 Burning: An economical and practical weed control method, it is used to (a) dispose of vegetation (b) destroy dry and mature weed tops (c) kill green weed growth, where mechanical/manual weeding and other common methods are impracticable. Normally practised after the harvest when weed seeds are also burned. Flooding: Effective against weed species that cannot withstand long periods of submergence. Flooding kills plants by reducing oxygen availability for plant growth. Success requires complete submergence of weeds for long periods. Mechanical weeders: Manual and power operated. The former include dry land weeder and cono weeder while the latter range from small rotary weeders to tractordrawn weeding implements such as multiple rotary weeders and ridgers Cultural methods Appropriate tillage, planting, fertilizer application and irrigation practices help in controlling weeds. However, cultural methods alone cannot control weeds and should be used in combination with other techniques. Aspects like the choice of variety, time of sowing, cropping system and farm cleanliness also help in controlling weeds. Cultural methods include: Selective crop stimulation: This is achieved by planting proper crops and their varieties, maintaining high plant populations, applying adequate fertilizer and using quality seed, among others. Adequate plant population and early vigour: Creating narrow space between rows of plants and increased crop density, lead to early crop canopy closure and help maximize the effect of crop competition. Stale seed bed: Seed bed management induces crops to germinate and grow faster, thereby smothering weeds. A stale seed bed is one where one to two weed flushes are destroyed before planting the crop. Most weeds germinate from the top 4 to 5 cm of the soil surface. If planting is delayed on a finally prepared seed bed and the topsoil has adequate moisture content, a flush of weed seedlings will appear in about a week s time. The weed seedlings can be destroyed either by herbicide or using a shallow, noninverting tillage implement like a blade harrow. Crop rotation: Crop rotation aids in weed control by changing the crop environment and avoiding an increase in the weed population. Two to six or more crop rotations are possible over numerous seasons. Multiple cropping systems: Inter-cropping or companion planting, offers more diversity and complexity within the same season or rotation. Carrots can be shaded by tomatoes and loosen the soil below. Double-cropping usually involves sequential cultivation of two different crop species in the same season. Such systems can maximize the benefits of the rotation while making effective use of available land resources. Summer fallowing: Soil and weed vegetation is exposed heat in absence of rainfall or irrigation. This dries seeds and sedges, and rhizomes, the overheated plant parts losing reproductive capacity on account of desiccation. Minimum tillage: Deep and frequent tillage brings more dormant weed seeds and rhizomes to the topsoil. The practice of zero tillage avoids weed seed buried in the soil. Time of sowing: An appropriate planting times helps the crop to be established and develop normally. Delayed sowing enables weeds to germinate and grow fast, utilizing soil nutrient, water, light and other resources. 83

109 Sowing or planting method: A planting method that leaves the soil surface rough and dry discourages early weed growth. In India, winter crops are sown after pre-sowing irrigation which leaves the top 3-5 cm of soil above the crop seeds in rough and dry tilth, deferring weed germination. By this time, the crop plants are sufficiently grown to fight weeds. Lowering area under bunds and paths: Uncropped areas are ideal places for rapid weed growth, creating potential production sources of weed seeds/roots or suckers every year. Therefore, the least possible area of land should be kept uncultivated. Weed control practices should also be adopted in these areas. Mulching: This suppress weed growth by increasing soil temperature and reducing exposure of the weed canopy between crop rows to sunlight. Straw, grass, leaves, compost and rotted sawdust can be used for organic mulching though plastic mulching is becoming more popular in commercial crops and vegetables Biological control Use of living organisms such as insects, disease-causing organisms, herbivorous fish, snails or even competitive plants. This does not eradicate weeds but reduces the weed population. This method is not useful with all types of weeds. Introduced weeds are the best targets for biological control. Differential growth patterns and the competitive ability of crop varieties, prevent weed growth. Thus, fast growing groundnut and cowpea are good weed suppressers. Insects kill plants by exhausting plant food reserves, defoliation, boring and weakening the structure of the plant. Pathogenic organisms damage host plants through enzymatic degradation of cell constituents, production of toxins, disturbance of hormone systems, obstruction in the translocation of food materials and minerals, and malfunctioning of physiological processes. Bioagents for weed control should meet the following criteria: Feed on or affect only one host and not other useful plants. Free of predators or parasites. Adapt readily to environmental conditions. Must be capable of searching the host by itself. Must be able to kill the weed or prevent reproduction. Must have sufficient reproductive capacity to overtake increase of its host species. The following are examples of biological weed control: a. Larvae of Coctoblastis cactorum, a moth borer, control prickly pear Opuntia sp., by tunnelling through the plants and destroying it. In India, it is controlled by cochinial insects Dactylopius indicus and D. tomentosus. b. Lantana camara is controlled by larvae of Crocidosema lantana, a moth that bores into the flower and stems, eating flowers and fruits. c. Cuscuta spp. is controlled by Melanagromyza cuscutae. d. Cyperus rotundus Bactra verutana a moth borer. e. Ludiwigia parviflora is completely denuded by Altica cynanea (steel blue beetle) Chemical control Herbicides are chemicals that kill or inhibit plant growth and have been greatly improved weeding efficiency over the past four decades, together with conventional weeding methods. 84

110 Over 150 herbicides are widely used for selective and non-selective weed control. These chemicals vary greatly in their (a) molecular structure, (b) mobility within plants, (c) selectivity, (d) fate in soils and (e) environmental response. Proper selection of the herbicide, its rate, time and method of application are very important for effective weed control and crop selectivity. Many developing nations have made a good beginning in the use of herbicides in agriculture, but more research is needed before extending herbicide use to new situations. Advantages Herbicides were developed in the West primarily to overcome the shortage of farm labour. However, over the past 40 years, developing countries have become aware of the following advantages of herbicides. Incessant monsoon rain makes physical weeding difficult. Herbicides are useful during the early crop growth period when many fields need weeding at the same time. Herbicides can control weeds emerging from the soil and eliminate weed interference with the crop even at a very early stage of crop growth. Herbicides can kill many weeds that survive by mimicry, for example, wild oat (Avena spp.) in wheat and barnyard grass (Echinochola spp.) in rice. Weeds that resemble crop plants usually escape physical weeding. Herbicidal control does not require strict plant row spacings. Herbicides ensure longer lasting control of perennial weeds and bushes than is possible with any physical control method. Many modern herbicides can translocate considerably deep in and damage the underground system of weeds. Herbicides are convenient to use on spiny weeds which cannot be removed manually. Herbicides are safe on erodible lands where tillage may accelerate soil and water erosion. Herbicides kill weeds in situ without permitting their spread tillage, on the other hand, may fragment the vegetative propagules of weeds and drag them to new sites. Herbicide sprays easily reach weeds growing in obstructed situations, such as utilityright-of-way, under fruit trees and on undulating lands. Other benefits of herbicides include (a) fewer labour problems, (b) greater possibility of farm mechanization, (c) easier crop harvesting and (d) lower cost of farm produce. In dryland agriculture, effective herbicidal control ensures higher water use by crops and less crop failures due to drought. Limitations Like any other method of weed control, herbicides have limitations, although these can be overcome with proper care. Important limitations in the use of herbicides: There is no automatic signal to stop a farmer applying the chemical incorrectly till the results are evident in the sprayed crops or in rotation crops that follow. Even when applied correctly, herbicides may interact with the environment with unintended results. Herbicide drifts, wash-off, and run-off can cause considerable damage to neighbouring crops. Depending upon farming diversity, a variety of herbicides must be stocked to control weeds in different fields. Requires considerable skill on the part of the user and any error can be very costly. 85

111 Crop failures in herbicide-treated soils, usually, cannot be made up by planting any alternative crop of one s choice. The selection of the replacement crop has to be based on its tolerance to the herbicide that has already been applied. 6.5 Case study - Integrated weed management in vegetable crops Weed interference is a major constraint to the production of vegetable crops. Nearly all vegetables grow slowly during the first few weeks following emergence and tend to be less competitive with weeds than many arable crops. The first third of the crop cycle is considered the critical period for weed competition for most vegetable crops, but this period is variable and depends on crop morphology, rate of growth and development, planting distance and weed species present in the field. Weed control in vegetable production is mainly based on cultural practices, including: Crop rotation Land preparation Relay cropping and inter-cropping Inter-row weeding or cultivation Use of mulching material such as paper, plastic film or plant residues. Chemical control is relatively poorly developed in vegetable crops. Thus, weed control practices should be integrated as much as possible at the smallholder farming level in tropical and subtropical zones Seed-bed management Many vegetable crops are grown in seed-beds to develop suitable seedlings for transplanting in the field. In such areas, weed interference can easily reduce the seedling stand and growth rate by up to a half or more. Therefore, good weed control is required to obtain high quality seedlings. Land preparation and crop rotation as described for directseeded and transplanted crops is also applicable for seed-beds. In this case, large soil clumps should be broken into small particles to enable the farmer to control the depth of seeding of small-seeded crops and to obtain good crop emergence. Hand weeding: Hand-weeding in vegetable seed-beds is tedious and time-consuming work, requiring at least person-days/hectare for a single hand-weeding. In short cycle seedbeds of around one month, three hand-weeding operations are necessary to obtain suitable seedlings. Soil fumigants: In developed countries, the ideal weed control practice for vegetable seedbeds is soil fumigation 2-3 weeks before seeding with potent chemicals such as methylbromide and allyl alcohol. These and other treatments such as dazomet and liquid metamsodium are also effective in the control of soil-borne pests and diseases.soil fumigation is usually costly and can be used for high-value crops. Solarization: An effective method for the control of weeds and other soil-borne pests in warm climates, this technique is safe for the operator and environment-friendly. Transparent 86

112 or black polythene film is used to cover the surface of wet soil for days before seeding during the warmest and most sunny period of the year, when temperatures reach at least 35 C-40 C. The method is cost-effective if the plastic film is reused. The technique offers the advantage that pest control in the soil allows reseeding of the area after the first harvest of seedlings, thereby increasing the availability of soil nutrients for crops. Combined with further mulching, this practice reduces the weed stand for seven months and increases tomato and squash yields by two and four times, respectively, compared to traditional farming methods. Many difficult-to-control weeds such as Imperata cylindrica L. Raeuschel, can be effectively controlled by this method. The purple nut sedge (Cyperus rotundus L.) is the most resistant weed to soil-solarization. The stand of this species is only reduced by per cent in solarized areas and complementary hand weeding is necessary to control plants emerging from below the heated soil layer. Another useful method in irrigated areas, is to prepare and irrigate the seed-beds to promote early emergence of weeds and to control these through cultivations or with the use of postemergence herbicides such as glyphosate (1.44 kg a.i./ha). After 10 days, the farmer may sow the treated area. This technique greatly reduces weed infestation, minimizing further hand weeding Direct-seeded and transplanted crops Crop rotation: The best approach to reduce weed infestation in vegetable growing areas is to develop a good crop rotation sequence. Effective crops include: sweet potato, which also has some allelopathic effects on many grass weeds and sedges, densely cropped maize and sorghum and some fast growing leguminous plants able to produce a leaf canopy in days after seeding such as yard-long bean and mung bean. Land preparation: When perennial grass weeds dominate, it is best to plough in such a way that roots, rhizomes and other subterranean propagules are exposed on the soil surface, facilitating desiccation by wind and sun. Ploughing should be as deep as the equipment will allow in heavy soils and one pass may not be enough to achieve ploughing depth. Deep ploughing buries weed seeds, generally delays their germination and distributes these throughout the worked soil zone where these remain viable, but dormant, until returned to the soil surface by further cultivation. Relay-cropping and inter-cropping: Relay-cropping is widely practised in Asia, involving the planting of a second crop before the first one is harvested. Usually, a vegetable crop is seeded or transplanted between rows of rice immediately after draining the irrigation water from the field for the last time (i.e. two weeks before harvesting the rice crop). Another practice used more often is simultaneous inter-cropping, usually resulting in higher total leafarea development and possibly, higher plant population. A high crop stand significantly reduces weed infestation. There are several combinations of inter-cropping vegetable crops such as mung beans or bush beans + corn, brassica crops + celery, tomato or onions, carrot + lettuce, onions, leek or peas, cucumber + pole beans, eggplant, radish, peas or sunflower, onions or garlic + 87

113 tomato, lettuce or carrot, tomato + onions, lettuce, parsley, carrot, Chinese cabbage or radish, leek + onions, celery or carrot. Use of mulching material: Several types of paper, black plastic film or dry straw and other crop residues have been used successfully for weed control and for the retention of soil moisture in several horticultural crops. In the Philippines, rice straw mulching is normally combined with manual weeding for weed control in vegetable farms. In India, mulching with sugarcane trash is a common method to control weeds in vegetable crops. In China, non-mulched areas required more person-days of hand-weeding/hectare than the black polyethylene mulch treatment. Plastic material should be placed on the surface of the cropping row, to prevent weed emergence, with holes to allow for crop growth. Chemical weed control: The best approach to minimize inputs and to avoid environmental problems such as herbicide residue build-up in the soil, is to apply weed killers in the crop row to a width of 20 cm. Band application reduces herbicide use by up to 75 per cent compared to an overall application. Weeds along the cropping row are controlled and the ones in inter-rows are removed through early cultivation. 88

114 Table 6.1 Selective herbicides for weed control in vegetable crops Herbicide Rate/dose (kg/ha) Recommended in vegetable crops Time of application Weeds controlled Alachlor (Lasso, 50 EC) Butachlor (Machete, 50 EC) Fluchloralin (Basalin, 45 EC) Metribuzin (Sencor, 70 WP) Methabenzthiozuron (Tribunil yield, 70 WP) Oxyfluorfen (Goal, 25 EC) Simazine (Tafazine 50 WP) Atrazine (Atrataf 50 WP) Trifluralin (Treflan, 48 EC) Oxadiazon (Ronstar, 50 EC) Metolalchlor (Dual 50 EC) kg/ha kg/ha kg/ha kg/ha kg/ha kg/ha Tomato, French bean, okra, ridge gourd, bottle gourd, pea, cabbage, cauliflower, onion, radish Tomato, okra, French bean, bottle gourd, ridge gourd, pumpkin, watermelon, squash, bitter gourd Tomato, okra, chilli, potato, brinjal, onion, garlic, bran's, cabbage, cauliflower, bottle gourd, bell pepper Potato, tomato, asparagus Peas, broad bean, garlic, onion Potato, onion, garlic, cauliflower, cabbage Pre-emergence Pre-emergence Pre-plant incorporation (PPI) Pre-plant and pre-emergence Pre-emergence Pre-emergence Control annual grasses and certain broadleaved weeds Control grasses and broadleaved weeds Broad-spectrum herbicide, controls annual grasses and some broad-leaved weeds Control annual weeds, grasses and broadleaved weeds, partial control of Cyperus Numerous grasses and broad-leaved weeds Control most grasses and some broad-leaved weeds 0.75 kg/ha Potato Pre-emergence -do (same as above) kg/ha Potato Pre-emergence -do (same as above) kg/ha kg/ha kg/ha Tomato, brinjal, chilli, garlic, brassica crops and many other umbelliferous vegetable crops Tomato, brinjal, chilli, onion and mustard Pre-plant incorporation (PPI) Pre-emergence Control annual grasses and broad-leaved weeds Annual broadleaved weeds, grasses and some sedges Pea, carrot, potato Pre-emergence Broad-spectrum control of weeds. Mostly annual grassy and few broad-leaved weeds 89

115 6.6 Conclusion In any weed management programme, it is often the little things that spell success or failure and it is often these same items that affect the cost of weed control. As with other aspects of successful farm management, weed control requires an equally high level of management to obtain optimum control while minimizing costs. A successful weed management programme requires accurate diagnosis of the problem, proper planning and implementation of the programme and finally, monitoring the success or failure of the programme. A good IWM should be flexible enough to incorporate innovations and the practical experience of local farmers, should have been developed for the whole farm and not just for one or two fields and hence, should be extended to irrigation channels, road sides and other non-crop surroundings from where most weeds find their way to crop fields. It should also be economically viable and practically feasible. 90

116 7 Integrated Nutrient Management 7.1 Introduction SOIL can be an acronym for Soul of Infinite Life as it sustains life on earth. The soil derived from parent rock or sediments by the process of weathering, consists of mineral inorganic components from the parent material, along with organic residues derived from living organisms plus water and air. As a natural source for mineral content and as a source and sink of organic matter, soil is essential for sustaining life. The Green Revolution, which launched intensive use of high yielding crop varieties coupled with other inputs like chemical fertilizer and irrigation, succeeded in boosting food supply, but also gave rise to challenges in terms of imbalanced fertilization the primary cause of soil degradation and decline in soil fertility. The real challenge is to sustain the pace of agricultural production despite decreasing per capita availability of arable land. Researchers have estimated that food production of 200 million tons and fertilizer consumption of 17 million tons would result in nutrient removal of 25 to 27 million tons, leaving a nutrient gap of about 10 million tons. Several soil and plant nutrient management options have been evaluated to sustain soil fertility to feed a growing population. These have focused on integrated nutrient management, balanced use of chemical fertilizers, use of organic manures and biofertilizers as well as the integrated farming system approach to improve both cropping systems and rural livelihood opportunities. 7.2 Soil texture and structure The physical properties (mechanical behaviour) of soil greatly influence its use and behaviour towards plant growth. Root penetration, drainage, aeration, retention of moisture and plant nutrients are linked with the physical condition of the soil. Physical properties also influence the chemical and biological behaviour of soil. The physical properties of soil depend on the amount, size, shape, arrangement and mineral composition of its particles. The properties also depend on the organic matter content and pore spaces. The important physical properties of soils are 1. texture, 2. structure, 3. area, 4. density, 5. porosity, 6. colour and 7. consistency. Soil texture refers to the relative proportion of particles or the relative percentage by weight of the three soil separates, namely sand, silt and clay, or to the size of soil particles. The 91

117 proportion of each size group in a given soil (the texture) cannot be easily altered and is considered as a basic property of a soil. Soil separates are defined in terms of diameter in millimetres of the particles. Soil particles less than 2 mm in diameter are excluded from soil textural determination. Stones and gravels may influence the use and management of land because of tillage difficulties, but these larger particles make little or no contribution to soil properties such as water-holding capacity and capacity to store plant nutrients and their supply. Gravel: 2-4 mm Pebbles: 4-64 mm Cobbles: mm Boulders: > 256 mm Another soil characteristic, soil structure is different from soil texture. Structure refers to the combination or aggregation of sand, silt and clay particles into larger secondary clusters. If one grabs a handful of soil, good structure is apparent when the sand, silt, and clay particles are aggregated into granules or crumbs. Both texture and structure determine pore space for air and water circulation, erosion resistance, looseness, ease of tillage and root penetration. However, while texture is an innate property of the native soil and does not change with agricultural activities, structure can be improved or destroyed readily by the choice and timing of farm practices. 7.3 Importance of soil ph on nutrient availability Soil ph is a measure of soil acidity or alkalinity and is sometimes called soil water ph. This is because it is a measure of the ph of the soil solution, which is considered the active ph that affects plant growth. Soil ph is the foundation of essentially all soil chemistry and nutrient reaction and should be the first consideration when evaluating a soil test. The total range of the ph scale is from 0 to 14. Values below the mid-point (ph 7.0) are acidic and those above ph 7.0 are alkaline. A soil ph of 7.0 is considered to be neutral. Nutrient availability is influenced strongly by soil ph. This is especially true for phosphorus, which is most available between ph 6.0 and 7.5. Elements such as iron, aluminum and manganese are especially soluble in acid soils. Above ph 7.0, calcium, magnesium and sodium are increasingly soluble. Phosphorus is particularly reactive with aluminum, iron, and calcium. Thus, in acid soils, insoluble phosphorus compounds are formed with iron, aluminum and manganese. At ph levels above 7.0, the reactivity of iron, aluminum, and manganese is reduced, but insoluble phosphorus compounds containing calcium and magnesium can become a problem. To maximize phosphorus solubility and hence availability to plants, it is best to maintain soil ph within the range of 6.0 to 7.5. Overliming can reduce phosphorus availability just as quickly as under liming. In general, the availability of nitrogen, potassium, calcium and magnesium decreases rapidly below ph 6.0 and above ph 8.0. Aluminum is only slightly available between ph 5.5 and ph 8.0. This is fortunate because, although plants require relatively large quantities of nitrogen, phosphorus potassium and aluminum can be toxic to plants. If managed properly, soil ph is a powerful regulator of nutrient availability. Manganese, zinc and iron are easily available when soil ph is in the acid range. As the ph of acid soil approaches 7.0, manganese, zinc 92

118 and iron availability decreases and deficiencies can become a problem, especially in soils that do not contain appreciable amounts of these elements. These micronutrients must frequently be supplemented with fertilizer when soil levels are low, when overliming has occurred, or when soil tests indicate a deficiency. There is a delicate balance between soil ph and nutrient availability. It is important for soils to be tested regularly and to maintain the ph in the recommended range for maximum efficiency of soil and fertilizer nutrients. 7.4 Role of nutrients in plant health Plant nutrient is a mineral element, considered essential to plant growth and development if the element is involved in plant metabolic functions and the plant cannot complete its life cycle without the element. Sixteen elements are considered essential for plants and are grouped according to their relative abundance in plants. Over 60 non-essential elements are also found in plants. The nutrients are classified into the following three categories based on the functions and abundance of the particular nutrient in the plant system Primary or major nutrients These are required in relatively large quantities by the plant for its growth. Nutrient Function Nitrogen (N) Phosphorus (P) Potassium (K) Basic component of proteins and chlorophyll (the pigment that gives the plants its green colour). Essential for plant growth. Also feeds soil microorganisms. Important for root growth and promotes establishment of young plants, flowering, fruiting and ripening, photosynthesis, respiration and overall plant growth. Moves through the plant. Promotes movement of sugars, turgor and stem rigidity. Also increases overall plant resistance to cold, disease and insect pests. Promotes the formation of flower buds, hardening-off of woody plants and fruiting Secondary nutrients Required by plants in moderate amounts and given secondary importance in its supply and management. Calcium (Ca) Plays a vital role in plant structure, because it is part of and holds cell walls together. Promotes development of the root system and the ripening of fruit and seeds. Found in the growing parts of plants (apex and buds). Magnesium (Mg) Sulphur (S) Micronutrients An important part of chlorophyll. Helps fruit ripening and seed germination. Reinforces cell walls and promotes absorption of phosphorous, nitrogen and sulphur by plants. A component of several proteins, enzymes and vitamins. Contributes to chlorophyll production. Helps plants absorb potassium, calcium and magnesium. Utilized by plants in relatively smaller quantities, but are equally essential to plants as macronutrients. 93

119 Iron (Fe) Boron (B) Manganese (Mn) Molybdenum (Mo) Chlorine (Cl) Copper (Cu) Zinc (Zn) Nickel (Ni) Silicon (Si) Cobalt (Co) Sodium (Na) Vanadium (Va) Essential for chlorophyll production. Also contributes to the formation of some enzymes and amino acids. Essential for overall plant health and tissue growth. Promotes fruit formation and water absorption. Promotes seed germination and speeds plant maturity. Plays important role in photosynthesis by contributing to chlorophyll production. Essential for nitrogen assimilation and protein formation. Essential for nitrogen assimilation by plants and nitrogen fixation by bacteria. This means that it is needed for the production of nitrogen-based proteins. Stimulates photosynthesis. Activates various enzymes. Also plays a role in chlorophyll production. Plays an important role in the synthesis of proteins, enzymes and growth hormones. Key component of selected enzymes involved in N metabolism and biological N fixation. Strengthens cell walls, energy transfer and resistance to drought. Reduces water loss and prevents fungal infection. Essential in N fixation. Na replaces K in certain functions in halophytes plants. For C4 plants having dicarboxylic photosynthetic pathway. Essential for green algae. 7.5 Importance of soil organisms Soils are tilled by soil organisms, not machinery. Once fertilized, the fertility is used again and again and never leaves the soil. Native soils are covered with a layer of plant litter and/or growing plants throughout the year. Beneath the surface litter layer, a rich complexity of soil organisms decompose plant residue and dead roots, then release their stored nutrients slowly over time. Topsoil is the most biologically diverse part of the earth. Soildwelling organisms release bound-up minerals, converting these into plant-available forms that are taken up by plants growing on the site. The organisms recycle nutrients again and again from the death and decay of each new generation of plants growing on the site. There are many different types of creatures on or in the soil and each has a role. These organisms work for the farmer's benefit if their survival is ensured. Consequently, these may be referred to as soil livestock. A great variety of organisms contribute to soil fertility, such as earthworms, arthropods and the various microorganisms, which merit particular attention Living soils Soil may seem lifeless, but is very much alive with millions of small organisms, if healthy and rich in organic matter. Some soil organisms can be seen with the naked eye, such as earthworms and small insects, but most can only be seen through a microscope. These microscopic organisms include nematodes (tiny worms), bacteria, fungi and even some insects. These living organisms make the soil alive and give it a good structure and texture. A living soil ecosystem nurtures and nourishes plants by providing a healthy medium to take roots and through a steady supply of nutrients. 94

120 The use of chemicals in fertilizer and pesticides destroys the natural soil ecosystem, damages soil health and ultimately kills the soil. Deteriorated/dead soils result in poor plant growth and reduce agricultural productivity. Stagnant and declining yields are quite evident in intensively cultivated areas. The creatures living in the soil are critical to soil quality, affecting soil structure and, therefore, soil erosion and water availability. These are central to decomposition and nutrient cycling and, therefore, affect plant growth and the amounts of pollutants in the environment. Finally, the soil is home to a large proportion of the world's genetic diversity Bacteria Bacteria are tiny, one-cell organisms. Most are decomposers that consume simple carbon compounds, such as root exudates and fresh plant litter. By this process, bacteria convert energy in soil organic matter into forms useful to the rest of the organisms in the soil food web. A number of decomposers can break down pesticides and pollutants in soil. Decomposers are especially important in immobilizing or retaining nutrients in their cells, thus preventing the loss of nutrients such as nitrogen, from the rooting zone (e.g. nitrifying bacteria) Fungi Fungi are microscopic cells that usually grow as long threads or strands called hyphae and push their way between soil particles, roots and rocks. Fungi perform important services related to water dynamics, nutrient cycling and disease suppression. Along with bacteria, fungi are important as decomposers in the soil food web, converting hard-to-digest organic material into forms that other organisms can use. Fungal hyphae physically bind soil particles together, creating stable aggregates that help increase water infiltration and soil water holding capacity Mycorrhizal fungi Mycorrhiza is a symbiotic association between fungi and plant roots and is unlike either fungi or roots alone. Most trees and agricultural crops depend on or benefit substantially from mycorrhizae. The exceptions are many members of the Cruciferae family (e.g. broccoli, mustard) and the Chenopodiaceae family (e.g. lambsquarters, spinach, beets), which do not form mycorrhizal associations. The level of dependency on mycorrhizae varies greatly among some crop varieties, including wheat and corn Soil protozoans Protozoa play an important role in mineralizing nutrients for use by plants and other soil organisms. Protozoa have a lower concentration of nitrogen in their cells than the bacteria they eat. Bacteria eaten by protozoa contain too much nitrogen for the amount of carbon protozoa needed. Protozoa release excess nitrogen in the form of ammonium (NH4+), usually near the root system of a plant. Bacteria and other organisms rapidly take up most of the ammonium, but some is used by the plant Nematodes Nematodes are non-segmented worms typically 1/500 th of an inch (50 µm) in diameter and 1/20 th of an inch (1 mm) in length. The few species responsible for plant diseases have received a lot of attention, but far less is known about the majority of nematodes that have 95

121 beneficial roles in soil. An immense variety of nematodes function at several trophic levels of the soil food web. Some feed on the plants and algae (first trophic level); others are grazers that feed on bacteria and fungi (second trophic level); and some feed on other nematodes (higher trophic levels) Arthropods Many bugs, known as arthropods, make their home in the soil and are named after their jointed (arthros) legs (podos). Arthropods range in size from microscopic to several inches in length and include insects such as springtails, beetles and ants; crustaceans such as sowbugs; arachnids such as spiders and mites; myriapods, such as centipedes and millipedes; and scorpions. Nearly every soil is home to many different arthropod species. Arthropods can be grouped as shredders, predators, herbivores and fungal-feeders, based on their functions in the soil. While feeding, arthropods aerate and mix the soil, regulate the population size of other soil organisms and shred organic material Earthworms Of all members of the soil food web, earthworms need the least introduction. As major decomposers of dead and decomposing organic matter, earthworms derive nutrition from the bacteria and fungi growing upon such material. Their fragmentation of organic matter makes a major contribution to recycling the nutrients it contains. Earthworms are found in most temperate and many tropical soils and at all depths, divided into 23 families, more than 700 genera and more than 7,000 species. The earthworm s length ranges from 2 cm to 2 m. In terms of biomass and overall activity, earthworms dominate the world of soil invertebrates, including arthropods. Earthworms dramatically alter the soil structure, water movement, nutrient dynamics and plant growth. While not essential for all healthy soil systems, their presence is usually an indicator of a healthy system. Earthworms perform several beneficial functions. 7.6 Soil testing Soil testing is defined as a programme for procedural evaluation of soil fertility by rapid chemical analysis particularly to assess the available nutrient status and reaction of a soil. A soil test is a chemical method for estimating the nutrient supplying power of a soil. Compared to plant analysis, the primary advantage of soil testing is its ability to determine the nutrient status of the soil before the crop is planted. The result of a soil test is known as soil test value which measures a part of the total nutrient supply in the soil and is only an index of nutrient availability. A soil test does not measure the exact quantity of a nutrient potentially taken up by a crop. To predict crop nutrient needs, a soil test must be calibrated against the response of crops in nutrient rate greenhouse and field experiments. Thereafter, interpretation and evaluation of the soil test values primarily form the basis for fertilizer recommendation Soil sampling The most critical aspect of soil testing is obtaining a soil sample that is representative of the field. There is considerable chance of a sampling error. If a sample does not represent a 96

122 field, it is impossible to provide a reliable fertilizer recommendation. Soils are normally heterogeneous and there can be wide variability even in uniform fields. Intensive soil sampling is the most efficient way to evaluate variability. The sampling error in a field is generally greater than the error in the laboratory analysis. Normally, for all field crops, a soil sample is obtained from up to 15 cm depth. For deep-rooted crops and tree crops, samples from up to 1-2 m depth may be necessary. When sampling, a uniform portion is first taken from the surface to the desired depth and then the same volume is obtained from each area Soil health card The soil health card evaluates the health or quality of a soil as a function of its characteristics, water, plant and other biological properties. The card is a tool to help farmers monitor and improve soil health based on their own field experience and working knowledge of their soils. Regular use allows them to record long-term trends in soil health and assess the effects of different soil management practices. The card is most effective when completed by the same person over time. It provides a qualitative assessment of soil health, and evaluation ratings do not represent absolute measures or value. The purpose is not to compare one soil type against another, but rather to use indicators that assess each soil s ability to support crop production within its capabilities and site limitations. Table 7.1 Model soil health card for paddy Source: Personal communication: Mobile Soil Testing Laboratory, Tamil Nadu State Agricultural Department, Tamil Nadu, India. 97

123 Table 7.2 Model soil health card for maize Source: Personal communication: Mobile Soil Testing Laboratory, Tamil Nadu State Agricultural Department, Tamil Nadu, India. 7.7 Soil nutrient management strategies Assessing soil health and biological activity A basic soil audit is the first, and sometimes, the only monitoring tool used to assess changes in the soil. Most farmer-recognized criteria for healthy soils include, or are created by soil organisms and soil physical properties. A better appreciation of these biological and physical soil properties, and how these affect soil management and productivity, has resulted in the adoption of several new soil health assessment techniques. A quick ways to identify a healthy soil is to feel and smell it. Does it have an earthy smell? Is it loose and crumbly with some earthworms present? The surface of the earth, if crusted, tells something about tillage practices used, organic matter and structure. Two more easy observations are counting the number of soil organisms in a square foot of surface crop residue and to pour a pint of water on the soil and record the time it takes to be absorbed. Comparisons can be made using these simple observations along with the soil health card (i.e. soil test results above to determine how farm practices affect soil quality). Some of the soil quality assessment systems discussed above utilize these and other observations and provide record observations sheets. 98

124 7.7.2 Techniques to build soil Bulky organic amendments have to be added to supply both organic matter and plant nutrients. It is particularly useful to account for nutrients where organic fertilizers and amendments are utilized. Knowing the amount of nutrients needed to supply the crop, guides the amount of amendment applied and can lead to significant reductions in fertilizer purchase. In addition to containing major plant nutrients, organic fertilizers can supply many essential micronutrients. Animal manure: Manure is an excellent soil amendment, providing both organic matter and nutrients. Typical rates for dairy manure would be 25 to 75 tons per ha. At these rates, the crop would get between 60 and 150 kg of available nitrogen per ha. A lot of carbon would also be added to the soil, resulting in no loss of soil organic matter. High crop residues grown from this manure application would also contribute organic matter. Compost: Composting farm manure and other organic materials is an excellent way to stabilize their nutrient content. Compost releases nutrients slowly, minimizing losses. Good quality compost has more humus than its raw components because of primary decomposition during the composting. Unlike manure, compost can be used at almost any rate without burning plants. Cover crops and green manure: Many types of plants can be grown as cover crops that maintain or increase soil organic matter if allowed to grow long enough to produce high herbage. In addition to the organic matter benefits, legume cover crops provide considerable nitrogen for crops that follow them. Consequently, the nitrogen rate can be reduced following a productive legume cover crop taken out at the correct time. Cover crops also suppress weeds, help break pest cycles and through their pollen and nectar, provide food sources for beneficial insects and honeybees. Reduced tillage: While tillage has become common in many production systems, its effects on the soil can be counterproductive. Tillage makes the soil surface smooth and reduces natural soil aggregation and earthworm channels. Porosity and water infiltration are decreased following tillage. Tilled soils have much higher erosion rates than soils covered with crop residue. Due to problems associated with conventional tillage, the area under reduced tillage systems is increasing. Minimized synthetic nitrogen fertilizer use: If possible, add carbon to nitrogen sources. Animal manure is a good way to add both carbon and nitrogen. Nitrogen fertilizer should be used at a time when heavy crop residue is being added to the soil. For example, a rotation of corn, bean and wheat would benefit with the addition of nitrogen after the corn residue is rolled down or lightly tilled in. Following the wheat crop, a legume cover crop can be planted Monitoring soil health improvement Experimenting with new practices and amendments should be accompanied by monitoring of the soil for changes, using tools discussed in the Assessing Soil Health and Biological Activity section. Effective INM requires the adoption of a microwatershed-based agricultural diversification through farming systems approach, comprising crop and animal husbandry, horticulture, bee-keeping and pisciculture. The goal of the farming systems approach is to 99

125 increase and stabilize farm production and farm income. Diverse enterprises create opportunities for recycling so that pollution is minimized because the waste of one enterprise becomes the input for another. Risk minimization, employment generation and sustained/increased household income are benefits associated with multi-enterprise farming systems. Appropriate and situation-specific farm diversification models need to be developed and diffused. Efforts are underway in different locations to develop farm diversification models involving a judicious mix of enterprises to generate attractive income besides meeting household demands. 7.8 Integrated nutrient management (INM) strategies for sustainable agriculture Adequate plant nutrient supply holds the key to improving foodgrain production and sustaining rural livelihoods. Farmers usually do not apply fertilizer at recommended rates as they think fertilizers are very costly and involve risk, particularly in dry conditions. Therefore, INM has an important role in promoting a mix of organic and inorganic fertilizers to fill the nutrient gap. Integrated nutrient management aims to maintain or adjust plant nutrient supply to achieve a given level of crop production by optimizing benefits from all possible sources of plant nutrients. While bulky organic manure may not supply adequate nutrients, its role becomes important in meeting the above objectives. Long-term studies indicate the possibility of substituting a part of the N need of kharif crop by Farm Yard Manure (FYM) without adverse effect on total productivity in major cropping systems such as rice-rice, rice-wheat, maizewheat, sorghum-wheat, pearl millet-wheat, maize-wheat and rice-maize. Organic manure alone cannot supply sufficient P for optimum crop growth because of low P concentration. Organic manure is known to decrease P adsorption/fixation and enhance P availability in P- fixing soils Recycling crop residues and green manuring Management of crop residue involves one of three methods removal, burning or incorporation into soil. In situ recycling of crop residue in rice-wheat rotation reduces the yield of both cereals. Therefore, most farmers recycle crop residue not by choice, but because of combine harvesting, burning the residue, resulting in the loss of precious organic matter, plant nutrients and environmental pollution. Experiments show that incorporation of green manure and crop residue of wheat and rice, reduces the adverse effect of unburned crop residue on crop yields Role of biofertilizers in INM Several studies have clearly indicated that Rhizobium is more effective among different biofertilizers. Considering an average N fixation rate of 25 kg N/ha per 500 g application of Rhizobium, it is expected that 1 ton of Rhizobium inoculants will be equivalent to 50 tons of nitrogen. On the other hand, Azotobacter, used in non-legume crops, has inconclusive results. Similarly, Blue Green Algae (BGA) and Azolla have been reported to be effective only in certain traditional rice growing areas. If BGA applied at 10 kg/ha, fixes 20 kg N/ha, then 1 ton BGA has an equivalent fertilizer value of 2 tons of nitrogen. The beneficial effect 100

126 of organisms like Azospirillum and Azotobacter in the suppression of soil-borne pathogenic crop diseases is yet to be established on a pilot scale. Another important biofertilizer role is the liberation of growth substances promoting germination and plant growth. There are several constraints to effective utilization and popularization of biofertilizers such as: Unlike mineral fertilizer, biofertilizer is crop-and location-specific. A strain ideal in one location may be ineffective in another due to competition from native soil microbes, poor aeration, high temperature, soil moisture, acidity, salinity and alkalinity and presence of toxic elements. Low shelf life of microorganisms. Unlike mineral counterparts, biofertilizers need careful handling. Lack of suitable carrier material for restoration and longevity in actual field conditions INM strategies for major cropping systems The following INM strategies for major cropping systems give an idea of integrating green manuring, biofertilizers, animal manure, farm yard manure with synthetic chemical fertilizers. Table 7.3 INM strategies for major cropping systems Cropping system Rice-wheat Rice-rice Rice-potatogroundnut Sugarcane-based cropping systems Maize-based cropping systems Soybean-wheat Pulses Sorghum-based cropping system Cotton Oilseeds (mustard, sunflower etc.) INM strategy Green manuring of rice with sun hemp equivalent to 90 kg fertilizer N with 40 kg N/ha produces yield equivalent to 120 kg N/ha. In acid Alfisol soil, incorporation of lantana camera days before transplanting of rice helps increase N use efficiency. Apply 75% NPK + 25% NPK through green manure or FYM at 6 t/ha to rice and 75% NPK to wheat. Inoculation of 10 kg/ha provides about kg N/ha. Use of organic sources, such as FYM, compost, green manure and azolla, meets 25-50% of N need in kharif rice and can help curtailing NPK fertilizers by 25-50%. Apply 75% NPK + 25% NPK through green manure or FYM at 6 t/ha to kharif rice and 75% NPK to rabi rice. Successful inoculation of blue green 10 kg/ha provides about kg N/ha. Use 75% NPK with 10 t FYM/ha in rice and potato. Combined use of 10 t FYM/ha and recommended NPK, increases cane productivity by 8-12 t/ha compared to chemical fertilizer alone. Apply 50% recommended NPK as fertilizer and 50% N as FYM in maize and 100% of recommended NPK as fertilizer in wheat. To produce 2 t soybean and 3.5 t wheat, apply 8 t FYM/ha to soybean and 60 kg N + 11 kg P/ha to wheat or apply 4 t FYM + 10 kg N + 11 kg P/ha to soybean and 90 kg N + 22 kg P/ha to wheat. Integrated use of FYM at 2.5 t/ha and 50% recommended NPK fertilizer plus rhizobium inoculation, helps save 50% chemical fertilizers. Substitute 60 kg N through FYM or green leuceana leaucocephala loppings to get higher yields. 50% of recommended NPK can be replaced by 5 t FYM/ha. Substitute 25-50% chemical fertilizer through 10 t FYM/ha for higher yield. 101

127 7.9 Conclusion Substantial research on integrated nutrient management has led to the development of INM practices for major crops; an understanding of the enhanced role of organic manure in increasing efficient input use due to the favourable effect of organic manure on the physical, chemical and biological condition of the soil; and the acceptance of the advantages of the integrated use of organic manure in improving nutrient cycling in different production systems in various soils. INM recommendations for different crops are not based on soil testing and nutrient release behaviour of the manure. The nutrient balance/flow analysis vis-à-vis soil fertility management practices, with special reference to INM at the farm level, needs to be worked out. The nutrient release characteristics of farm residues have to be determined in relation to their quality, to develop decision support systems. Biofertilizers were not included as an INM component in many cases, and the Integrated Farming Systems (IFS) approach needs to be encouraged to sustain rural livelihoods, particularly for small and marginal farmers. 102

128 8 Role of Pest Surveillance in IPM 8.1 Introduction The current trend in plant protection is to limit the application of pesticides through nonchemical methods such as planting pest-tolerant or resistant varieties, adoption of suitable cultural and mechanical measures and the use of natural enemies. This is popularly known as the Integrated Pest Management approach where pesticides are the last resort. Pest surveillance determines the need, area and the time for pest control. It also aims to study the trend and sequence of pest development in a given crop ecosystem, to identify resurging and potential problems, irrespective of the current level of damage and losses caused by the pests. This enables determination of research priorities to find solutions to emerging problems. Another objective of pest surveillance is to generate field data on the pest ecology for some years for correlation with various crops and weather parameters in order to develop advance warning systems. Vital information, such as the occurrence of pest biotypes, crop reaction to pests and disease in a given region, and magnitude of crop loss can also be obtained through pest surveillance. Pest surveillance can also provide information on likely biocontrol agents in field conditions. This is essential for determining the type of control measures needed for the Integrated Pest Management programme. 8.2 Survey, surveillance and forecasting Pest survey The survey is a planned activity measuring and recording factors observed in a single period or over an extended period of time. Most surveys involve a number of field workers. It is important to minimize variation in data collection caused by personal preferences, by standardizing the survey methodology and preferably keeping it simple. Data recording is best done with standard scales that assign numerical values for collected data. Pro forma data collection sheets should contain such scales so that field workers only have to note the approximate numerical design for the factor being reported. There are two types of surveys, based on the methodology of the survey, namely roving survey and fixed plot survey. 103

129 Roving survey: This is used to assess pest population/damage from randomly selected spots in a large area. Fixed plot survey: This assesses the pest population/damage in a fixed plot/field. The data on pest population/damage is recorded periodically from sowing till harvest. In both the cases, field workers enter the field and walk at least 10 m before starting to select 25 plants at random, following a zig-zag route. Observations are recorded at weekly intervals (e.g. 1 m² plots, randomly selected from twelve spots in a crop area of one ha in case of rice). Ten plants are selected at random from each plot. Total tillers and tillers affected by stem borer in these 10 plants are counted. Total leaves and number affected by leaf folder are observed. Damage is expressed as a percentage of damaged tillers or leaves. Population of Brown Plant Hopper (BPH) from all tillers in the 10 plants is observed and expressed as number/tiller. Specific survey: Procedure by which National Plant Protection Officers (NPPOs) obtain information on the pest of concern in specific sites in an area over a defined period of time. A survey can also be categorized as: Detection survey: Conducted in an area to determine if pests are present (e.g. to detect fruit fly species). Delimiting survey: Conducted to establish the boundaries of an area considered to be infested by or free from a pest. Also considers the extent of a problem (e.g. to detect presence of Mango stone weevil, determining spread of Paracoccus marginatus). Monitoring survey: Ongoing survey to verify characteristics of pest population. Repeated to identify trends and evaluate effectiveness of steps to contain, suppress or eradicate the pest Pest surveillance Pest surveillance refers to the constant watch on the population dynamics of a pest, its incidence and damage on each crop, at fixed intervals to forewarn farmers of crop protection measures. Pest surveillance is the systematic monitoring of biotic and abiotic factors of the crop ecosystem in order to predict the pest outbreak or it is the study of the ecology of the pest which provides necessary information to determine the feasibility of a pest management programme. Pest surveillance programmes provide information on pest population dynamics and key natural mortality factors in field conditions for devising appropriate management strategies Pest forecasting Forecasting pest incidence or outbreak, based on information obtained from pest surveillance. 8.3 Basic components of pest surveillance Pest surveillance has three basic components: 1. Determination of the level of incidence. 2. Determination of the loss the incidence will cause. 3. Determination of economic or other benefits of control. 104

130 The above information is of immense use in determining the need for a pest control measure. The mere presence of a few numbers of a pest species should not be the criterion for pesticide application which requires sufficient justification. Surveillance can provide the necessary information to determine the feasibility of a pest control programme. The usefulness of pest surveillance can be best illustrated by the example of the rice tungro virus transmitted by green leaf hopper in north-east India some years ago, which caused serious losses for two years. Effective surveillance began from the third year of the outbreak and the problem was checked, avoiding the use of large quantities of insecticide. Another example was the brown plant hopper epidemics in India s south-western State of Kerala in Initially, farmers could not identify the pest because it feeds at the basal portion. The following year, the State Government set up surveillance units and the pest was brought under control. 8.4 Sampling techniques and their application It is not feasible to count every individual in the pest population and it is more efficient to estimate population density by sampling. The sampling technique depends on: i. Pest activity (flying/mobile/sessile; diurnal/nocturnal) and feeding behaviour [chewing (internal/external) or sucking]. ii. Disease occurrence soil-borne/air-borne/seed-borne, part of the plant/whole plant affected, plant death (incidence)/necrotic lesions on part of the plant (e.g. leaf) and severity Types of sampling Random sampling: This is the easiest method with a number of samples from the population selected at random to ensure equal chances of selection for every sample. Stratified random sampling: The population is divided into different strata and random samples obtained from these. The strata are subdivisions of the samples, based on knowledge of the distribution of the population. Cluster sampling: Area is considered in clusters. Variance is calculated separately for clusters within the area. Sequential sampling: Total number of samples to be taken in an area is unknown when sampling is begun. This type of sampling usually allows the decision to be made with fewer samples, saving time and money. Systematic sampling: Sampling at fixed intervals. The first sample is taken at the reference point and subsequent samples regularly along this route. 105

131 8.4.2 Sampling methodologies These depend on the type of pest, its distribution and stage Direct sampling Direct sampling, counting or observation of pest stages (i.e. directly visualizing pests). Done with direct observation or using devices including traps. a. Net sweeping: The points to be considered in this method are (1) the time of sampling (2) density and height of the crop (3) the number of sweeps required and (4) the type of insect pest being studied. A sweep consists of a half circle or 180 swing with the hoop of a 43-cm insect net with a handle length of 1 m. Usually, 10 sweeps may be sufficient to assess the general population of any species and the population is reported in terms of number per 100 sweeps. This method is useful for insects like adult beetle, leaf hopper, nymph and adults of bug and grasshoppers. b. Waterpan method: A wide mouthed plastic container is used with water. A few drops of detergent solution or teepol are added to reduce the surface tension and/or facilitate the easy settling of insects at the bottom of the container. The plastic container with water is placed at the bottom of rice plants and the hills are tapped three times so that insects fall into the container. At least 10 hills are tapped and the insects collected may be separated into pests and defenders. This method is useful for insects feeding at the basal portion of the rice plant. c. Sudden trapping: The insects in a unit area are trapped suddenly with a suitable trap without causing any disturbance and counted. This method is useful for insects like grasshopper and sorghum earhead bug. d. Light trap: Useful for quantitative estimation of the seasonal abundance of several species of many adult moths and other insects attracted to light. The brood emergence of the rice stem borer Scirpophaga incurtulas is fixed by light trap catches. e. Suction trap: In this method, the flying insects are trapped by sucking air into a trap with a suction apparatus operated either by hand or a motor. With a timing mechanism, it is possible to have hourly catches. f. Adhesive or sticky traps: A suitable, persistent adhesive material like grease or taris spread on strips of paper and supported on a cylinder. The sticky trap is set in a field and traps flying insects. Factors like wind velocity, temperature and colour of the trap have a bearing on the number of insects caught. It is important to collect and clean the traps often to maintain their efficiency. g. Bait traps: A variety of bait, ranging from raw plant material and crushed insects, to refined chemical attractants stimulating sexual or food odour, are known to attract insects. This type of sampling is more complex and utilized in the case of fruit flies. h. Crop samples: The population of the insect in the crop samples drawn is counted and recorded. This method is widely followed for insect pests such as the rice stem borer, 106

132 sorghum stem borer, gall midge, aphid, thrip and bollworm. However, the techniques are still to be improved depending upon pest species and crop. For example, to estimate the population of aphids, leaf hoppers and thrips in cotton, leaves from terminal, central and basal portion of the plant are examined. i. Fixed volume or area of soil: Soil insects like grubs are counted from a fixed area and depth of soil by cutting out cylinders of soil 10 cm in diameter and 25 cm deep. A sample of 50 quadrates (i.e. 50 cylinders of soil) is taken from 1 ha and it can be multiplied by 1,247,400, which is the number of quadrates that can be taken from 1 ha, to estimate the population in 1 ha (e.g. white grub) Indirect sampling a. Direct injury: Sampling techniques involved with most of these measures are the direct observation of results of insect injury such as the number of leaves mined by leaf miners, percentage defoliation by hairy caterpillars and armyworms, number of wilted or dead plants with dead hearts/white ears/silver shoots caused by borers/midges. b. Insect products: Larval and pupal skins, frass, honey dew (e.g. secreted by aphid, whitefly), nests of colonial insects are used as indicators in sampling (e.g. the measurement of frass drop in a collecting tray) to assess the population size of several forest pests. 8.5 Sampling programmes and parameters Sampling programmes a. Intensive sampling Designed for specific objective, mostly research (e.g. population ecology research) For population dynamics research All or most stages in the life cycle of an insect are sampled with a high degree of precision Sampling is done frequently b. Extensive sampling Designed for broad objective (e.g. to determine species distribution) The status of injurious insect stages Usually a single insect stage is sampled Only a few samples taken per season Sampling parameters The assessment of the insect population is very important as the population density of the pest is generally related to the extent of damage it causes. The study involves two major aspects, namely (i) stage of the pest whether egg, larva or nymph, pupa or adult at counting and (ii) actual process of counting and estimating. It may not be possible to count all insects on a crop in the field and population assessment should use samples. The essential aspects of sampling include the distribution of pests, nature of the sample, mode of sampling, size and number of samples, and population estimation by computation and analysis of sample 107

133 counts. It is desirable to take samples at regular intervals and to the extent possible, at the same time of the day. a. Insect stage to be sampled: Basically the population of the most injurious stage of the pest is counted like the larvae or the nymphs or both nymphs and adults. b. Number of sampling units: It is desirable to fix the minimum sampling number depending on the nature of the crop and pest distribution. However, it is always better to have a larger number of samples. The sampling units should be representative and homogeneous. c. Time to sample: Samples may be taken regularly (once or twice per week), depending on the pest and crop cycle. d. Pattern of sampling: The most used sampling patterns are X, W, U, diagonal, microplot and a fixed row length. Edges are usually avoided in making estimates unless required by species distribution (e.g armyworms, grasshoppers, stalk borers). 8.6 Designing a surveillance programme When planning a new survey, the details of the design need to be carefully recorded and justified. The reasons for a specific survey include: To develop a list of pests or hosts present To demonstrate a pest-free area or places of low pest prevalence for trade purposes To develop a baseline list of pests before monitoring for changes in pest status For pest management and control For early detection of exotic pests For early detection of established organisms that become pests The designing of specific surveys includes the following steps: 1. Selection of a title and assignment of authors 2. Identification of target pest: pest name, vector, diagnostic characteristics, collection of reference insect specimens and images, pest information sheet including all information regarding host range and others. 3. Identification of target host: weeds or alternative plants 4. Review of earlier survey plan 5. Site selection, area, district selection and sampling sites selection 6. Calculation of sample size 7. Timing and frequency of survey 8. Planning how to collect data in the field 9. Analysis of data 10. Reporting of results Code Numbers for recording general information in rapid roving survey of rice: i. Variety: Local (1)/Dwarf (2) ii. Planting method: Broadcast (1)/Transplanted (2) iii. Crop stage: Seedling (1)/Tillering (2)/Booting (3)/Heading (4)/Milk (5)/Mature (6) iv. Crop appearance: Healthy (1)/Yellowing (2)/Browning (3)/Dead (4) v. Soil moisture: Flooded (1)/Muddy (2)/Dry (3) vi. Weather: Sunny (1)/Rainy (2)/Cloudy (3)/Windy (4)/Drizzle (5) vii. Weeds: Trace (1)/Slight (2)/Moderate (3)/Heavy (4) viii. Suspects: NPK (1)/Microelement deficiency (2)/ Virus (3)/Physiological(4) 108

134 Stem borer (Dead Heart /White Ear) Gall midge Stem borer moth Stem borer egg Green leaf hopper Brown plant hopper White backed plant hopper Leaf roller Rice Hispa Case worm Whorl maggot Army worm Climbing cutworm Rice earhead bug Mealy bug Thrips Root weevil Grasshopper Table 8.1 Scale and methodology for roving pest survey in rice (For recording insect pest incidence, 0-9 scale is used) Select randomly at five places in field and examine five hills in each location; count total number of tillers and number of Dead Heart/White Ear. Galls to be worked out and put in a 1-9 scoring scale according to severity. Score: 0= nil; 1= less than 1%; 3=2-4%; 5=5-10%; 7=11-20%; 9=more than 20% Number of moths to be disturbed by 10 steps inside the field and to be put in 1-9 scale. 0=nil; 1=1-2; 3=3-5; 5 =6-10; 7=11-20; 9=more than 20 Stem borer egg mass recorded per clump while examining 25 clumps for stem borer/dead Heart/White Ear and placed in 1-9 scale. 0=nil; 1=less than 1; 5=1-2; 9=more than 2; 9=more than 2 10 clumps in an acre, examined diagonally across and number of adults per hill recorded and placed in 1-9 scale. By single knock to 20 hills at (10+10 clumps) to be examined diagonally across and counted on per hill basis and placed in 1-9 scale. 0=nil; 1= less than 1 per hill; 3=2-4 per hill; 5=5-10 per hill; 7=11-50 per hill; 9=more than 50 Same as for brown plant hopper. 25 hills examined and damaged leaf per hill. Counted; placed in 1-9 scale. 0=no damage; 1= less than 1; 3=1-2; 5=2-3; 7=4-10; 9=more than 10 damaged leaf/hill. Same as for leaf roller. Same as for leaf roller. 25 clumps/hill examined as for stem borer DH/WE and number of damaged leaves recorded according to 1-9 scale. 0=no damage; 1=2 leaves damage; 3=5 leaves damaged; 5=50% of the total leaves damaged; 7=75% of the total leaves damaged; 9=more than 75% of total leaves damaged Using visual observation, estimate scores as follows: 0=none; 1=light; 5=moderate; 9=severe Same as for army worm. Ear heads of 10 hills examined and number of bugs counted on per hill basis. 0=none; 1=1 No./hill; 3=2-5 No./hill; 5=6-10 No./hill; 7=11-20 No./hill; 9=more than 20 No./hill Visual observation of patches caused by attack of mealy bug and scored from 0 to 9. 0=No damage; 1=2% of area damaged; 3=2-4% of area damaged; 5=5% of area damaged; 7=6-10% of area damaged; 9=more than 10% area damaged Visual estimation to estimated % of damage. 0=none; 1=5% damage (light); 5-10% damage (moderate); 9=more than 50% damage Uproot clump with soil and splash in water. Count number of white grubs per hill by examining three clumps. The average number of grub per plant/hill recorded and reproduced in scale 1-9. Number counted as for stem borer moth. 109

135 8.7 Establishment of pest surveillance system in various countries Rice pest surveillance system in Asia began as early as the 1940s when heavy pest infestations in Japan led to food shortages. Pest surveillance started in India in 1969, after a widespread epidemic of tungro. Malaysia established a pest surveillance system in 1979 following outbreaks of the brown plant hopper. Pest surveillance and early warning systems were initiated in the Philippines in 1975 and in Thailand in 1983 with support from the German Agency for Technical Cooperation. In Indonesia, pest surveillance began in 1975 and there are now more than 2,000 pest observation units in the country. The Repubic of Korea initiated pest surveillance in 1958 and 151 observation units now collect rice pest and disease information in the country. Pest surveillance is an important component of rice pest management in China with more than 4,000 pest observers said to be employed by plant protection stations across the country. India established Locust Warning Organizations in 1929 and Central Pest Surveillance Stations were established in Advances in pest surveillance a. Remote sensing: Remote sensing methods such as radar, can automatically monitor the height, horizontal speed, direction, orientation, body mass and shape of insects. Imagery from remote sensing satellites can be used to identify pest-affected areas and the intensity of pest damage. The technique is useful for pests producing visible symptoms of crop damage over a large area (e.g. hopper burn symptoms in paddy and to identify long-distance pest migration as in locusts). b. E-pest surveillance: This uses a special device with provisions for sending real-time data to a computerized system which issues suitable advisories. c. Mobile pest surveillance: Mobile phones with necessary software enable data to be uploaded for receiving advisories. 8.9 Conclusion Pest surveillance is the most important step in plant protection programmes, including domestic route surveillance and quarantine pest surveillance. Pest surveillance must be proactive so that the timely management measures can be adopted and epidemics avoided. Pest surveillance facilitates the management, eradication, suppression or containment of plant pests. There are various types of surveillance activities. General and Specific Surveys are designed according to needs and objectives. Special surveys like detection, delimiting and monitoring need to be combined at times. Fixed Plot and Rapid Roving Surveys are conducted as routine surveillance activity to detect and manage domestic crop pests for implementation of effective IPM programmes. 110

136 9 Role of Biological Control Approaches in Pest Management 9.1 Introduction In agroecosystems, the components of modern intensive agriculture such as high yielding varieties and excessive use of fertilizer and irrigation, alter the crop physiology, morphology and phenology, attracting insect pests and diseases. Synthetic pesticides were developed in the early 1940s. With the success of pesticides, biological, cultural and mechanical controls were often underutilized or disregarded as viable pest management strategies. Further consequences of overreliance on pesticides became apparent over the following decades. The first requirement for pest management is the knowledge of crop and associated organisms. Biological control is one of the most important components of integrated pest management, promoting natural enemies of key crop pests. IPM is a sustainable, viable and ecological solution to the pest problem, using three approaches, namely importation, conservation by modifying the environment and periodic release by mass multiplying bioagents. 9.2 Biological control agents Entomophages These are organisms feeding on insects. Predator: Attacks and feeds entirely from the outside of the host, usually by piercing the host organism cuticle and damaging its internal organs before sucking. Some larger predators devour the entire body. In many predatory insects, only the larval stage actively feeds on the prey. Adults survive on insect honeydew, plant nectar and pollen. However, in predators such as ladybird beetles, both the larval stage and the adult feed actively on the prey. Parasitoid: A parasitoid usually has a free-living adult stage and a larval stage that develops on or within a single host organism, ultimately killing the host. Parasitoids can be further classified as ectoparasitoids that live and attack from the outside of the host and endoparasitoids that develop from an egg laid within the host. Eretmocerus eremicus and Encarsia formosa are both parasitoids of whitefly nymphs. Parasitoid wasps can be further classified by dividing their ovipositional lifestyles into either idiobionts or koinobionts. Idiobionts totally paralyse their host, the majority being ectoparasitoids that deposit an egg (or more) next to the host that develops outside the prey body, sucking nutrients from the 111

137 living but paralysed body (e.g. the leaf miner parasitoid Diglyphus isaea). Koinobionts are endoparasitoids and cause no signs of parasitism until the host has reached a suitable size and the young hatched parasitoid larva begins to grow and consume the host. The leaf miner parasitoid Dacnusa sibirica is a koinobiont, developing only when the leaf miner has pupated; however, the majority of parasitoids attack the young stage of the exposed host. Both parasitoids and host develop together to pupation (i.e. aphid parasitoid Aphidius spp.) Entomopathogens These are microorganisms infecting and causing disease in their host and killing it. Major pathogens are fungi, viruses and bacteria. Some nematodes also cause diseases in some insect pests. Important examples of fungi include different species of Hirsutella, Beauveria, Nomurae and Metarhizium. Among viruses, the most important examples are of nuclear polyhedrosis viruses (NPV) and granulosis viruses. Among bacteria, Bacillus thuringiensis (B.t.) and B. popillae are common examples Fungal antagonists These are biological control practices for plant protection from fungal pathogens using the deployment of antagonistic fungal microorganisms in the field before or after infection. Although many microorganisms interfere with the growth of plant pathogens in the laboratory, greenhouse or in the field, and provide some protection from disease, so far only few microorganisms have been registered and are commercially available. Examples include Trichoderma harzianum/t. viridae for control of several soil-borne plant pathogenic fungi Mycopathogenic bacteria These are bacterial agents antagonistic to plant pathogenic bacteria and can be applied as soil treatment or as foliar spray. Examples include Pseudomonas fluorescens against Rhizoctonia and Pythium and Bacillus subtilis Nematopathogens These kill plant parasitic nematodes. Many soil-inhabiting microorganisms like bacteria, fungi and protozoans are parasites and antagonistic to plant parasitic nematodes. For example, nematophagous fungi are microfungi that capture, kill and digest nematodes, using special mycelial structures, their so-called traps, or spores to trap vermiform nematodes, or hyphal tips to attack nematode eggs and cysts before penetration of the nematode cuticle, invasion and digestion. A few fungal nematopathogens such as Paecilomyces lilacinus and Verticillium chlamydosporium, and bacterial nematopathogens such as Pasteuria penetrans and Pseudomonas fluorescens are commercially available for field use. 9.3 Biological control approaches Biological control approaches can be categorized as (i) classical biocontrol or importation of natural enemies or biocontrol organisms for the management of exotic pests, (ii) augmentation through inoculative or inundative approaches and (iii) conservation of biological control agents available in the nature. The three approaches can be practized 112

138 alone or in combination Classical biological control The intentional introduction of an exotic, usually co-evolved, biological control agent for permanent establishment and long-term pest control of exotic pests is called classical biological control. Insects are often introduced into new areas either accidentally or by design. Sometimes, the introduced insects, also known as exotic or non-indigenous insects, find a suitable host plant(s) in their new habitat for survival and reproduction. When an exotic insect is introduced, it often does not have any co-evolved natural enemies. As a result, the exotic insect soon becomes a pest. This is probably the most successful, yet controversial biological control method. For classical biological control to be successful, the natural enemy should also originate from a region with a climate similar to the one in which it is being introduced. Obviously, if the exotic natural enemy cannot survive and reproduce, it will not be an effective biological control agent Augmentation This is a method of increasing the population of a natural enemy, either a parasitoid or predator and can be done by mass-producing in a laboratory and releasing at the proper time. Another method is periodic colonization by natural enemies. There are two basic approaches of augmentation inoculation and inundation. Inoculation biological control: The intentional release of a living organism as a biological control agent with the expectation that they will multiply and control the pest for an extended period, but not permanently. Inoculation is used where a native natural enemy is absent or an introduced species is unable to survive permanently. Inoculative releases are made at the beginning of the season for seasonal control (i.e. to colonize the area for the duration of the season or crop) and prevent pest build-up. Inundation biological control: The use of living organisms to control pests when control is achieved exclusively by the released organisms themselves. Releases made with biological control through inundation involve very large numbers of native or introduced natural enemies, in a way similar to the application of chemical pesticides. The natural enemies selected for inundative release need not possess all attributes desired of a species imported for permanent establishment. However, their ability to cause high host/prey mortality and the rearing and application cost are of outstanding importance in an inundative release programme. Examples: Mass release of Trichogramma egg parasitoid, Acerophagus papayae predators like Coccinellids spp., Chrysoperla zastrowii sillemi and Reduviids Conservation of natural enemies Modification of the environment or existing practices to protect and enhance specific natural enemies or other organisms to reduce the effect of pests is termed as the conservative approach in biological control. Conservation is achieved by using pest control measures that preserve or enhance natural enemies (e.g. planting refuge crops) or by avoiding pest control measures that harm natural enemies (e.g. broad-spectrum pesticides). It can be an 113

139 important alternative to the widespread use of pesticides as well as a significant component of sustainable agriculture. Conservation of natural enemies can be achieved in the following manner: i Preservation of inactive stages: This is the most critical approach, when there is a small reservoir of natural enemies outside the cropped area ( e.g. Pupae of Epipyrops are found in large numbers on the trashes of sugarcane leaves at the time of harvesting). These are left around harvested fields to augment the supply of natural enemies in the pre-monsoon season against pyrilla. ii iii iv v Avoidance of harmful cultural practices: Cultural practices like burning can be harmful to natural enemies (e.g. burning of sugarcane trash destroys the resting stages of Epipyrops). Such practices can be modified to avoid harmful effects. Maintenance of diversity: The concept that the more the diversity, the more the stability, holds true because diverse systems may provide alternate hosts as sources of food, overwintering sites and refuge ( e.g. mixed cropping, intercropping). Natural food, artificial food supplements and shelters: Many parasitoids and predators require food/alternate hosts, frequently not available in monoculture. The availability of predatory mites was related to the availability of pollen. Artificial honeydew and pollen in the form of food sprays induced early oviposition of Chrysoperla spp. Protection from pesticides: All pesticides have adverse effects on natural enemies. The solution lies in the use of relatively resistant strains of natural enemies and the selective use of pesticides. 9.4 Mass production and use of biological control agents Mass production of host insects Many biological control agents can be produced only through in-vivo technologies. For this purpose, mass production of the host is an important component of biocontrol agent production Mass production of rice moth, Corcyra cephalonica With the increased awareness of integrated pest management among farmers, there is increasing emphasis on the utilization of bioagents. The rice meal moth, Corcyra cephalonica stainton (Lepidoptera: Pyralidae) ranks first in the mass culturing of entomophagous insects due to its amenability to mass production, adaptability to varied rearing conditions and positive influence on the progeny of natural enemies. It has proved to be a most efficient surrogate host for rearing a wide range of biological control agents. The important among these are egg parasitoids Trichogramma spp. egg larval parasitoids Chelonus blackburni, larval parasitoids Bracon spp., Goniozus nephantidis and Apaneteles angaleti. Insect predators Chrysoperla carnea, Mallada boinensis and Cyrtorhynus feltiae (Neoaplectana carpocapsea) are reared on the larvae of C. cephalonica. Some entomopathogenic nematodes such as Steinernema feltiae are also reared on the larvae of Corcyra cephalonica. Only an efficient and healthy insect mass rearing medium can result in the mass production of effective biological control agents. Corcyra can be mass multiplied 114

140 throughout the year in all ecological zones of India at 28 C ± 2 C and 65 ± 5 per cent relative humidity, considering the economics as well as quality of eggs produced. Rearing basins: The host rearing containers (basins) are made of a non-toxic and cheap material of optimum size to permit mating and host-searching, and easily cleaned. The basins (40 cm diameter) used for Corcyra multiplication are thoroughly cleaned with 0.5 per cent detergent wash and rinsed in tap water followed by wiping with a dry and clean used towel and drying in the shade. Whenever the trays are emptied after a cycle of rearing, these should be cleaned with 2 per cent formaldehyde and stored until further use. The cleaning steps are repeated on reuse. Preparation of feed material: Corcyra feed may be prepared from bold white sorghum grains without any insecticide residue. This can be tested by taking a sample of 100 g from each bag. The crushed sample is fed to 20 numbers of 1st/2nd instar Corcyra larvae for 2-3 days. Based on the mortality of the larvae, the suitability of grains may be decided. The requisite quantum of sorghum is milled to make 3-4 pieces of each grain. Sorghum grain is heat-sterilized in an oven at 100 C for 30 minutes and sprayed with 0.1 per cent formalin. This treatment helps in preventing the growth of moulds and restores grain moisture lost due to the heat, to the optimum of per cent level. Grain is then air-dried. Preparation of Corcyra eggs: The primary source of Corcyra eggs are reputed laboratories and commercial producers for bulk preparation. If it is intended to begin production with a nucleus colony, the adult moths can be collected from warehouses where food is stored. The eggs used for building up the Corcyra colony have to be free from contaminants like moth scales and broken limbs and should not be exposed to UV light. Collections of eggs laid overnight are measured volumetrically to ascertain the number of trays that can be infested with eggs. One cc of eggs is known to contain approximately 16,000-18,000 eggs. Corcyra charging: The overall production scheme involves initial infestation of the sorghum medium with Corcyra eggs in desired quantities. This is accomplished by sprinkling the freely flowing eggs on the surface of the medium in individual basins. Per basin, 0.5 cc eggs of Corcyra are infested. The basins are then covered with clean khada cloth and held tightly with rubber fasteners. Yeast, groundnut kernel and streptomycin are added to enhance egg-laying capacity of the adult moths and for enriching the diet. The basins are carefully transferred to racks. 115

141 Handling the trays: The larvae that hatch out in 3-4 days begin to feed on the fortified sorghum medium. At this stage, light webbings are noticed on the surface. As the larvae grow up, they move down. During this period, the larvae are allowed to grow undisturbed in the trays. Collection of moths: After about days of charging, moths start emerging and the emergence continues for two months. 10 to 75 moths emerge daily with peak emergence between the 65th and 75th day. Adults are either aspirated with mechanical moth collector or collected with specimen tubes. The whole operation is carried out inside a mosquito net. This prevents large-scale escape of moths, which can migrate to the storage area and spoil stored grains by laying eggs. Workers involved in the moth collection should wear face masks continuously to avoid inhalation of scales. Collect moths daily and transfer to the specially designed oviposition cages or oviposition 1,000 pairs per drum at a time for egg-laying. The oviposition drums of 30 x 20 cm are made of galvanized iron. The drums rest on tripod frames with legs 5 cm high. The drum bottoms have wire meshes for the collection of eggs. The drum walls have two vents (ventilation holes) opposed to each other. The vents are again covered with wire mesh. The drum lids have handles besides slots for introducing the moths and adult feed. The oviposition drums filled in a day are maintained for 4 to 7 successive days for egg collection and then emptied and cleaned for the next cycle of use. The adults are provided feed containing honey solution. The adult feed is prepared by mixing 50 ml honey with 50 ml water and 5 capsules of vitamin E (Evion). The feed is stored in a refrigerator for later use. A piece of cotton wool tied with a thread is soaked in the solution and inserted into the drum through the slot at the top. Moths can be collected from a basin for up to 90 days, after which the number of moths emerging dwindles and keeping the basins is not economical. Handling of eggs: Moths lay eggs in large numbers and loosely. Scales and broken limbs are also found in larger quantities with the eggs. This can be hazardous to workers after years of working in a Corcyra laboratory. To minimize the risk of scales freely floating in the air, the oviposition drums are placed on sheets of filter paper in enamel trays which trap the scales. Sets of several oviposition drums are kept in a ventilated place near an exhaust fan for the workers comfort. Every morning, the oviposition drums are lifted up and the wire-mesh bottoms are brushed to collect the eggs of Corcyra. The collections are cleaned by gently rolling the eggs on filter paper to another container. These are then passed to sieves in series and finally the clean eggs are collected. The eggs are quantified in measuring cylinders and used for building up stocks and natural enemy production. 116

142 About 100 pairs of adults produce 1.5 cc of eggs in a 4-day laying period inside the oviposition drums. From each basin, 2,500 moths are collected on average. Hence from each basin, cc of eggs can be obtained in 90 days. Maintenance of history sheet: Accurate information is needed on the history of individual basins. The following information is furnished: 1. Date of egg infestation 2. Date of preparation of feed 3. Source of egg 4. Expected date of adult emergence 5. Daily collection of moths 6. Problems encountered with the basin during production 7. Personnel handling the basin Rearing of Helicoverpa armigera and Spodoptera litura on artificial diet Diet preparation: The larvae of gram pod borer and tobacco caterpillar can be multiplied by using a chickpea- based semi-synthetic diet. The composition of the diet for rearing larvae is as follows: Fraction Name of the ingredient Quantity of the ingredient 'A' fraction: Chickpea (Kabuli channa) flour g Methyl para-hydroxy benzoate 2.00 g Sorbic acid 1.00 g Streptomycin sulphate 0.25 g 10% formaldehyde solution 2.00 ml 'B' fraction: Agar-agar g 'C' fraction: Ascorbic acid 3.25 g Yeast tablets 25 tablets Multivitaplex 2 capsules Vitamin E 2 capsules Distilled water ml Fraction A of the diet is mixed with 390 ml of water in the blender for 2 minutes. Fraction B is boiled in the remaining 390 ml water. Fraction A and B are mixed in the blender again for 1 minute. Finally, fraction C is also added to the mixture of A and B in water and the blender run again for 1 minute. Formaldehyde solution is added in the end. The diet is poured as per requirement, either on the petri plate or plastic container for rearing up to 5-7 days-old larvae or in tray cells for rearing above 5-7 days-old or poured into a sterilized petri plate and allowed to solidify. The diet can be stored in the refrigerator for up to two weeks. The quantity of diet ingredients has to be calculated according to the number of larvae to be reared. 117

143 Initiation of the culture: The adults collected in a light trap can be used for egg-laying, which can be used for initiation of the culture. Alternatively, Helicoverpa, Spodoptera larvae can be collected on a large scale from host crops in endemic areas for initiating the culture. Transfer of moths to the cage: Under a suitable temperature regime, adults emerge about 8-12 days after pupation. Females usually start to emerge 1-2 days before males. The males and females can be separated by the colour of the forewings. In males, the forewings are greenish. In females, the colour varies, ranging from pink to dark brown. Every morning, after the eclosion, moths are transferred to the cage. Moths are provided with a 10 per cent honey solution or a sucrose solution in a small petri dish. Collection of eggs: The eggs are laid all over the inner surface of the covered cloth. The cloth with eggs is removed daily. The cloth with the eggs is surface-sterilized in 10 per cent formalin for 10 minutes. The eggs could also be surface-sterilized by 0.2 per cent sodium hypochloride solution for 5-7 minutes and treated with 10 per cent sodium thiosulphate to neutralize the effects of sodium hypo chlorite solution and rinsed in distilled water five times for about 10 minutes. The eggs are later placed on a paper towel under the laminar flow hood for drying by switching on the air flow, but not under the UV light. The dried cloth pieces containing eggs are kept in 2-l flasks containing moist cotton. The flasks are plugged in cotton, wrapped in muslin cloth and the bottom of the flask is wrapped with aluminium foil. Transfer of the larvae to semi-synthetic diet: The diet is poured as per requirement, either on the nylon mesh for rearing 5-7 days-old larvae or in tray cells for rearing older larvae or poured into sterilized petri plates and allowed to solidify. The larvae are removed from the top of the aluminium foil-wrapped flasks with a brush and then transferred to the diet. Larvae (around 200 in number) are transferred to the diet, impregnated on nylon mesh and placed in plastic containers or sterilized glass vials. 100 such containers are maintained daily for 5-7 days. Multicellular trays with a semisynthetic diet are advantageous for rearing a large number of larvae. Diet requirements at various stages of production of larva: 2 g/larva for young larvae up to 5-7 days-old. 4 g/larva for 5-7 days-old larvae for Ha NPV production. 6 g/larva for 5-7 days-old larvae for continuation of host culture. 1 kg for rearing field-collected larvae for augmenting nucleus stock. In host culture units, larvae start pupating when they are days-old and the pupation is over within 2-3 days. The egg, larval, pupal and adult stages of Helicoverpa larvae last for 3-4, 18-29, 7-8 and 7-9 days, respectively. The female oviposition period is about 5 days. Separation of pupae: Under the conditions mentioned earlier, the larvae stop feeding after approximately 23 days, begin wandering and burrowing into the remaining diet to form a pupation cell. Here, the larvae become the pre-pupae. The pre-pupal stage lasts for 2-3 days before pupation. Once formed, pupae should be left undisturbed for a few hours until the soft, newly formed cuticle which is pale yellow-green is fully hardened, turning redbrown, before removing from the pupal cell using blunt-nosed steel forceps. Deformed 118

144 pupae are discarded at this stage. The sexes should be kept separately in 300 ml dishes, half-filled with dry vermiculite or sterilized, insecticide-free saw dust with a maximum of 50 pupae per dish. If disease is a problem, pupae should be surface-sterilized at each generation, but not until 2-3 days after pupation, by when the pupal cuticle would have fully hardened. The pupae should be transferred 3-4 days before the start of adult emergence to Perspex cylinders, 36 cm high, with a diameter of 20 cm and having ventilated lids. The bottom of each cylinder is filled with a 2 cm layer of vermiculite on which 50 to 60 pupae are placed. Adult emergence can be delayed for about 2-3 weeks by keeping the pupae at temperatures down to 12 C. Control of pathogens in the culture: The three principal pathogens that are potential threats for the establishment of H.armigera culture are Viruses (NPV), Microsporidia/protozoa (Nosema/Vairimorpha spp.), Fungi (Aspergillus spp.) and a range of bacteria. The following precautions are taken to maintain a virus-free culture: Routine surface sterilization of eggs and pupae. Rearing equipment and reusable containers soaked in iodoform disinfectant, washed with detergent and rinsed several times in hot water at 80 C. Disposable petri dishes and 30 ml larval rearing pots used only once. Diseased and dead larvae disposed off without opening it. To control microsporidia, select healthy lines. Dead and sick larvae must be checked for Nosema/Vairimorpha for many generations. The insectary hygiene and sterilization procedure as described for NPV control also helps to reduce the incidence of Nosema. For managing fungi and bacteria, the following procedure helps reduce contamination: Equipment should be thoroughly cleaned. Sterilize ground seed flour at 70 C for three hours in dry heat. Add to diet ingredients and antibiotics, methyl-4-parahydroxy benzoate and sorbic acid to reduce spoilage. Whenever possible, keep uncovered trays of diet in a laminar flow cabinet to reduce the chances of contamination by air-borne pathogens Rearing of mealy bug on pumpkin Planococcus citri, Ferrisia virgata and Maconellicoccus hirsutus are multiplied using pumpkins and potato sprouts. Multiplication on pumpkin: Different species of mealy bugs can be produced on ripe pumpkins. Only good quality pumpkins should be selected. Pumpkins with ridges and grooves with a stalk are washed thoroughly with tap water to remove dust particles. The pumpkins are then dipped in 0.1 per cent solution of Bavistin to kill all fungal pathogens. Alternatively, alcohol or formalin can be used. Wounds on pumpkins can be plugged with hot paraffin wax. The pumpkin is then dried in a shade and infested with mealy bug crawlers (first instar). In the absence of crawlers, ovisacs of mealy bugs are placed over the pumpkin. The crawlers emerging from ovisacs then settle down on the pumpkins. Each infested pumpkin is placed in a 30 cm wooden cage having all sides covered by a white cloth or white nylon mesh. The pumpkin is placed in the cage through the front door, on a round plastic 119

145 ring. Such pumpkins are covered fully by mealy bugs within 15 days and the mealy bugs mature in another days. Fresh pumpkins should be regularly infested with mealy bugs to ensure the availability of the right stage of mealy bugs for exposing to the coccinellid predators. A novel method, tying a thread across the length and around the pumpkins, has been found to be successful in getting crawlers to settle evenly on pumpkins without ridges and furrows. The tied threads simulate ridges of pumpkin or leaf veins, and hence used as shelter by crawlers. This helps in using pumpkins without furrows Rearing of diamond back moth (DBM) on mustard seedling Cabbage seedlings or mustard seedlings are used for the mass multiplication of P. xylostella. Mustard seedlings are grown in small ice cream cups with vermiculite or in wooden trays containing an equal mix of red soil, sand and farm yard manure. The mustard seeds dibbled in ice cream cups by either way are allowed to germinate and proper moisture is provided to ensure maximum germination of the seedlings. Five days after germination, the seedlings are placed in an insect rearing cage 3 x 2.5 x 2.5 m. All sides of cage are covered by nylon mesh but the top is covered by an acrylic sheet. Two hundred DBM pupae are kept in a small petri plate and placed inside the cage. The emerging adults are fed on 30 per cent honey and water-soaked swabs. Adults are allowed to oviposit on the leaves of mustard for 24 hours. After this, the seedlings are removed and placed in trays in a cage. Upon hatching, larvae feed on mustard seedlings which are completely eaten away. The larvae from these seedlings are shifted to another set of fresh seedlings by chopping and placing remnants of the old seedlings on fresh seedlings. The pupae are formed in about 15 days, collected and placed in an oviposition cage and the production procedure continued. The pupal stock in the oviposition cages is renewed once in 5-6 days, so that a continuous supply of eggs or larvae is maintained. The mustard seedlings or trays can be raised as needed Mass production of parasitoids Mass production of egg parasitoid, Trichogramma The genus Trichogramma is cosmopolitan in distribution and present in all terrestrial habitats and is one of 80 genera in the family Trichogrammatidae. Trichogramma are primary parasitize eggs of Lepidoptera, but parasitism also occurs in eggs of other orders such as Coleoptera, Diptera, Hemiptera, Hymenoptera and Neuroptera. It is important for plant protection because of its widespread natural occurrence and its successful use as a biological control agent by mass release. As this parasitoid kills the pest in the egg stage itself before the pest can cause any damage to the crop and is also quite amenable to laboratory mass production, it has the distinction of being the highest produced and most utilized biological control agent in the world. Trichogrammatidae includes the smallest of insects, ranging in size from 0.2 to 1.5 mm. Trichogramma is difficult to identify because it is so small and has generally uniform morphological characteristics. Also, certain physical characteristics, such as body colour and the number and length of body hair, can vary with body size, season, rearing temperature and the host on which the adult was reared. A major advance in the systematics of Trichogramma was the discovery that characteristics of male genitalia can be used to identify species. This is the primary means of identification now, but body colour, wing venation and features of the antennae are supporting characteristics. 120

146 Females cannot be identified with the same level of confidence, so collections submitted for identification must include males in addition to physical characteristics. Studies of reproductive compatibility and mode of reproduction also have been especially valuable in identifying species. Preparation of Trichocards: The parasitization of Trichogramma spp., in laboratory conditions on 1 cc eggs of Corcyra cephalonica, which are uniformly spread and pasted on a 15 x 10 cm card, is called as Trichocard. The card has 12 demarcations (stamps). About 12,000 Trichogramma adults emerge from this card in 7-8 days after parasitization. To delay the emergence of Trichogramma, the cards can be stored in a refrigerator at 5 C -10 C for days. On removing the cards to room temperature, the parasitoids emerge normally. Trichocards have a shelf life of 2-3 days. However, these can be stored in a refrigerator for one month without any spoilage. Label information of the manufacturer, parasitoid species, date of parasitization and expected date of emergence is provided in the space left over. A coat of 10 per cent gum arabic is applied on the grids and the eggs are sprinkled uniformly in a single layer with the aid of a tea strainer. Excess eggs pasted are removed by gently passing a shoe brush over the card after air-drying under a fan. The egg cards are placed in polythene bags of suitable size and the nucleus card of Trichogramma are introduced. The easiest way to do this is to place a piece of Tricho egg card containing parasitized eggs (i.e. pharate adults) that are ready to yield adults and to hold these in subdued light for 2 to 3 days. The emerging parasites readily parasitize the fresh eggs. Precautions: Poor quality mass-reared Trichogramma can result in control failure. The artificial conditions of mass rearing can lead to genetic changes that reduce the effectiveness of the Trichogramma in the field. Such rearing conditions include rearing multiple generations on unnatural host eggs, the absence of plants, crowding and interference, rapid generation time and failure to rejuvenate genetic stock. Production colonies should be periodically replaced with individuals from a stock culture maintained on the natural or target host. Standards for established cultures on Corcyra are 95 ± 5 per cent egg parasitization, 90 ± 5 per cent adult emergence, and a sex ratio of 1 to 1.5 females per male. 121

147 Figure 9.1 Mass production of egg parasitoid Trichogramma Other precautions: Trichocards should be packed so that the parasitized surface is on the inner side. Emergence date should be specified on cards for the guidance of users. Trichocards should be stapled on the inner-side of the leaf to avoid direct sunlight. Card should be stapled in the morning hours and just before emergence to avoid predation. Farmers should refrain from using pesticides in the field where Trichogramma are released. If necessary, selective/safer pesticides can be used and it should be ensured that the pesticide use takes place 15 days before or after the release of Trichogramma. Figure 9.2a Packaging of Trichogramma cards Figure 9.2b Field release of Trichogramma eggs 122

148 Mass production of egg-larval parasitoid, Chelonus blackburnii A parthenogenetic egg-larval parasitoid, C. blackburnii has a fairly wide host range but the common meal moth Corcyra cephalonica has often been used for multiplication of this parasitoid. It could also be multiplied successfully on Spodoptera exigua. C. blackburnii has been used for the biological suppression of P. operculella, Earias vitella, Pectinophora gossypiella and Helicoverpa armigera on cotton and other host plants. It is becoming an important component of IPM systems on potato, cotton and other crops. Mass production procedure: A set of 100 eggs of Corcyra (not exposed to UV) that are 0-24 hours-old, are pasted on a 5 x 5 cm card. This card is exposed to 30 C. blackburnii adults in a 1.5 l container. The plastic container should have windows with plastic mesh for aeration. Two cotton swabs, one soaked in 10 per cent honey solution and the other in drinking water, are also placed inside from the side opening which is tightly closed with a cloth-covered cotton plug. After exposure to C. blackburnii for 24 hours, the egg card is removed and placed on 500 g sterilized pearl millet or sorghum medium. In 30 days, adults start emerging from the cocoons formed in the medium after completing development on Corcyra larvae. The adults live for 25 days and their fecundity is about 400 eggs Mass production of larval parasitoids, Bracon hebetor/b. brevicornis Bracon hebetor Say and B. brevicornis (Wesmael) (Braconidae: Hymenoptera) are highly polyphagous gregarious ecto-larval parasitoids of several Lepidopteran insect pests of field and horticultural crops as well as stored grains. These attack the larval stage of the insect host and lay eggs on the surface of the host insect. Upon hatching, Bracon larvae start feeding on the host body fluids by inserting mouth parts into the host. From each host larvae, two or more parasitoid larvae develop and pupate. The egg period is 1-2 days, larval period is 2-4 days, pupal period is 3-7 days and the adult lives for days. The total developmental period (egg to adult emergence) on larvae of Corcyra is 6-12 days. The eggs are laid singly or in groups of 2-8 each. A female is capable of laying 229 eggs ( ) on host caterpillars during its lifespan. The female lays between 2 and 27 eggs per day, laying the maximum number of eggs during the first 10 days of the oviposition period. Bracon spp. play a significant role in controlling important insect pests such as Helicoverpa armigera, Spodoptera litura, Hellula undalis, Crocidolomia binotalis, Earias vitella, Pectinophora gossypiella and Opisinia arenosella in various crop ecosystems. Releasing 3,000-5,000/ha can effectively control the insect pests listed above. Production procedure of Bracon hebetor/b. brevicornis Tub method: Take 250 g of roughly ground sorghum (each grain broken into 2-3 pieces) in a plastic tub and spread to a thickness of 0.5 cm. Place a cotton swab with 10 per cent honey on the inner side of the tub. Release larvae (second-fifth instars) of rice moth Corcyra cephalonica, in the tub. Release Bracon adults of mixed sex, which are either freshly emerged or 1-2 day-old in the tub, immediately covering the tub with a muslin cloth and securing it with a rubber band. Keep the tub undisturbed for days except for changing the cotton dipped in 10 per cent honey solution, once every two days and disturbing the Corcyra feeding tunnels once a week. With this method, it is possible to get 1,000-3,000 Bracon adults in days from one tub. When the Bracon adults have to be 123

149 released into the field, place the tub containing adults in the centre of the field and open the cloth. The adults will disperse in the field. Pot method: Take 50 g of roughly ground sorghum (each grain broken into 2-3 pieces) in an earthen pot of l volume. Release larvae (second-fifth instars) of C. cephalonica in the pot. Release Bracon adults of mixed sex, which are either freshly emerged or 1-2-day-old in the pot, immediately covering the pot opening with a muslin cloth and securing it with a rubber band. Take an empty 0.5 l plastic disposable water bottle and insert a piece of cotton dipped in 10 per cent honey solution in the opening of bottle. Make a small hole in the muslin cloth covering the pot opening and insert the bottle opening into it (bottle stands upside down). Change the cotton dipped in honey solution, once in two days. Add Corcyra larvae into the pot through the small hole in the muslin cloth once in five days. Bracon adults emerge continuously and are collected in the bottle. When Bracon adults have to be release in the field, replace the bottle containing adults with a new bottle and take the bottle to the field for release. Maintain the pot in a similar fashion for continuous mass production of Bracon adults. Figure 9.3a Life stages of Bracon hebetor Egg (1-2 days) Larva (2-4 days) Pupae (3-7 days) Adult (20-63 days) Figure 9.3b Mass production of Bracon in tub method Clean dry tub Tub with cotton dipped in 10% honey solution Tub with 250 g roughly ground (each grain broken into 2-3 pieces) sorghum Tub covered with muslin cloth 124

150 Figure 9.3c Mass production of Braconin (sandwich method) Mass production of Goniozus Goniozus nephantidis is the most widely used parasitoid of black-headed caterpillar. It is a sturdy gregarious larval or prepupal ectoparasitoid. The female practises maternal care of eggs and larvae. The host larvae are paralyzed and the parasitoids even feed on the host body fluid. The parasitoid is also capable of suppressing the population by stinging and paralyzing the 1st or 2nd instar larvae. Production procedure of Goniozus: The parasitoid is multiplied on Corcyra larvae in diffused light. A parasitoid pair is introduced in tube (7.5 x 2.5 cm). The adults are provided with honey in the form of small droplets on wax-coated paper. After a pre-oviposition period of six days, one healthy last instar Corcyra larva is provided in a vial. The parasitized Corcyra larva (i.e. containing eggs of Goniozus) are removed regularly from the vials till the death of the female. Such larvae are kept in strips of paper in plastic boxes covered by muslin cloth. Considering the fecundity as 20-50, the female is capable of parasitizing 6-7 larvae in three oviposition spells each separated by 4-5 days. The life cycle of the parasitoid is completed in days (incubation hours, larval feeding hours, prepupal stage hours and cocoon period hours plus resting adult inside the cocoon hours). 125

151 9.4.3 Mass production of predators Mass production of Chrysoperla carnea The green lacewings, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) is a cosmopolitan predator found in a wide range of agricultural habitats. It is important for the management of bollworms and aphids in cotton and tobacco and several sucking pests in fruit crops. It is capable of bringing down the population of the pest drastically. In India, 65 species of chrysopids belonging to 21 genera have been recorded in various crop ecosystems. Morphology and biology: The eggs are stalked and green in colour. The length of the egg in various species ranges between 0.7 to 2.3 mm and that of the stalk between 2 to 26 mm. The eggs are laid singly or in clusters. Eggs turn pale whitish and then black before hatching. The egg period lasts 3-4 days. The larva is white in colour on hatching and has three instars which are completed in 8-10 days. The larva spins a cocoon from which the adult emerges in 5-7 days. On emergence, adults mate repeatedly. Generally, the pre-oviposition period lasts for 3-7 days. Adult females start laying eggs from the 5th day and the peak egg-laying period is 9-23 days after emergence. The male has a longevity of days and the female can even live up to 60 days. Fecundity is eggs/female. The male-female ratio is 1:0.85. Adult males and females live 41 and 53 days, respectively. Mass production procedure: The adults are fed a variety of diet. The larvae are either reared in plastic tubes or empty injection vials or in groups in large containers or in individual cells. Adults are collected daily and transferred to pneumatic glass troughs or G.I. round troughs (30 x 12 cm). Before allowing the adults to emerge, a brown sheet is wrapped around the troughs and acts as the egg receiving card. About 250 adults (60 per cent females) are allowed into each trough and covered with white nylon or georgette cloth secured by rubber band. Three bits of foam sponge (13 sq cm) dripped in water are kept on the cloth outside. An artificial protein-rich diet in semi-solid form is provided in three spots on the cloth outside. This diet consists of one part of yeast, fructose, honey, Proteinex R. and water in the ratio of 1:1:1:1. Adults lay eggs on the brown sheet. The adults are collected daily and allowed into fresh rearing troughs with fresh food. The brown paper sheets with Chrysoperla eggs are removed from the old troughs. The brown paper sheet kept inside the adult-rearing trough contains a large number of eggs, each laid on a stalk or pedicel. The sheets are stored at 10 C in B.O.D. incubator or a refrigerator for about 21 days. When the eggs are required for culturing or for field release, the egg sheets are kept at room temperature for a day when the eggs turn brown and hatch 3 days later. The first larvae are either taken for culture or for field release. 126

152 Group rearing of grubs: Done in GI round basins (28 cm 250 larvae/basin, covered with cloth. The eggs of Corcyra cephalonica are provided as feeding material for the larvae in the laboratory. For rearing 500 Chrysoperla larvae, the total quantity of Corcyra eggs required is 22 5 cc/feeding for five feedings on alternate days. The Chrysoperla larvae pupate into round, white-coloured silken cocoons in 10 days. The cocoons are collected with a fine brush and transferred into 1 l plastic containers with wire mesh windows for the emergence of adults. Pale-green adults with transparent lace like wings emerge from the cocoons in 9-10 days. Figure 9.4 Mass production of green lace wing Chrysoperla carnea Individual rearing of grubs: In the first step of larval rearing, 120 three-day-old chrysopid eggs are mixed with 0.75 ml of Corcyra eggs (the embryo of Corcyra eggs are inactivated by keeping at a distance of 60 cm distance from a 15-watt ultraviolet tubelight for 45 minutes in a 27 x 18 x 6 cm plastic container). On hatching, the larvae start feeding. On the 3rd day, the larvae are transferred to 2.5 cm cubical cells of plastic one per cell. Each louver can hold 192 larvae. Corcyra eggs are provided in all the cells of each louver by sprinkling through the modified salt shaker. Feed is provided in two doses. First feeding of 1.5 ml Corcyra eggs for 100 larvae and second feeding of 2 ml for 100 larvae with a gap of 3-4 days. Total quantity of Corcyra eggs required for rearing 100 chrysopid larvae is 4.25 ml. The louvers are secured on one side by a brown paper sheet and after transfer of larvae, covered with acrylic sheet and clamped. 127

153 Brown paper is used for facilitating pupation and clear egg visibility. The louvers are stacked in racks. One 2 m x 1 m x 45 cm angled iron rack can hold 100 louvers containing 19,200 larvae. Cocoons are collected 24 hours after formation when hardened by removing orgami or paper from one side. The cocoons are placed in adult oviposition cages for emergence (Adults are sometimes allowed to emerge in louvers and released on glass window panes from where they are collected using suction pumps) Mass production of reduviids The reduviid bugs, also known as assassin bugs, are predators of insect pests. About 7,000 species of reduviid bugs have been reported worldwide. Two reduviid bugs, Rhynocoris marginatus/r. fuscipes are important and effective predators of insect pests in many agroecosystems such as soybean, groundnut, pigeon pea, cotton, castor, rice, cabbage, tobacco, pumpkin, okra, citrus, sugarcane, sesbania and apple, feeding on Spodoptera spp., Helicoverpa armigera, Achaea janata, Euproctis spp., Dysdercus cingulatus, Mylabris indica, Mylabris pustulata, Oryctes rhinoceros, Aproaerema modicella, Odentotermes spp., Chrotogonus sp, Pseudoplusia includens, Musca domestica, Pectinophora gossypiella, Aphis craccivora and Drosophila spp., among others. Predaceous reduviids are of considerable economic importance as these reduce the pest population by killing the host quickly with their highly proteolytic saliva. The effectiveness of reduviids as biocontrol agents has been demonstrated and field releases usually result in quick and effective control of target pests. Adult bugs range from 4 to 40 mm in length and usually have an elongated head with a distinct narrowed neck, long legs and a prominent, segmented tube for feeding, known as a rostrum/beak. Most species are dark in colour with hues of brown, black, red or orange. Reduviid bugs feed on a wide range of soft-bodied insects, mainly caterpillars. In the laboratory, reduviid bugs are mass-produced using rice moth (Corcyra cephalonica) larvae as hosts. The egg period is 7-10 days, nymphal period is days and the adult period is days. Mass production using plastic tub/container method Sterilized sand is added to a depth of 2 cm in a clean, dry plastic tub/container. Place a cotton swab dipped in a 10 per cent honey solution on the side wall of the tub/container. Place a piece of corrugated white paper for oviposition. Add 2-3 grown up larvae (4th-5th instars) of Corcyra. Release a pair or 2-3 pairs of young reduviid adults (male-female ratio of 1: 1) collected either from the field or obtained from a biocontrol agent production facility, into the tub/container. Cover the tub/container immediately with a muslin cloth and secure it with a rubber band. Change the cotton swab with honey solution and add Corcyra larvae every two days. 128

154 Figure 9.5 Mass production of predator reduviid bug Females lay eggs on the corrugated white paper in clusters of eggs. Collect egg masses from the white paper by cutting out the paper with eggs on it. Place the paper with the egg mass in a petri dish and cover it with a lid. Eggs hatch into nymphs in 7-10 days. Maintain the nymphs in the same petri dish for a week, adding 3 to 4, 1st/2nd/3rd instar Corcyra larvae or as needed. Place a small cotton piece dipped in 10 per cent honey solution. After a week, transfer all the nymphs to a plastic tub/container (10-20/container) with a sand layer, 2 cm thick at the bottom and a piece of corrugated white paper. Place a cotton swab dipped in a 10 per cent honey solution on the side wall of container. Add 3-5 fourth/fifth instar Corcyra larvae daily in the container. Cover the container with a muslin cloth and secure with a rubber band. Replace the Corcyra larvae and cotton dipped in honey solution every two days. Maintain the nymphs like this for days or until the adult stage (increase the number of Corcyra larvae added as the nymphs grow). During this period, nymphs go through five nymphal instars. Collect the adults and release a pair of adults (male and female) in a clean, dry tub and repeat the procedure for mass production of reduviids under laboratory conditions. The first and second nymphal instars can consume one small size host caterpillar/day; third and fourth nymphal instars can consume 2 to 3 medium-sized host caterpillars a day; fifth nymphal instar and adult can consume 3 to 4 large-sized host caterpillars a day. 129

155 9.4.4 Mass production of microbial biopesticides Identification of important biocontrol fungi Fungal pathogens, parasites and antagonists are exploited to control a variety of pests (arthropods, nematodes, weeds and crop diseases). Entomopathogenic fungi such as Beauveria, Metarhizium, Paecilomyces and Verticillium, fungi affecting nematodes like Arthrobotrys and Monacrosporium as well as egg parasitic fungi like Paecilomyces lilacinus and Verticillium chlamydosporum are used extensively. Similarly, Trichoderma spp is the fungal antagonist (biocontrol agent) for soil-borne diseases Biocontrol mechanism of fungal and bacterial bioagents Various mechanisms are reported to be involved in the biocontrol activities of biocontrol agents such as mycoparasitism, antibiosis, replacement or nutritional competition. In a broad sense, biocontrol activities are divided according to the antibiotic metabolites involved. The antagonistic activity of the biocontrol agent may be due to various compounds produced during their interaction with the target pathogen. The determination of the type of mechanism will enhance understanding of the biocontrol agent and also assist in formuling the strategy for mass multiplication Isolation of fungi and bacteria from soil, plant parts and insects Mycology and bacteriology requires the isolation in the field, from among thousands of fungi and bacteria, a single interesting species. A natural substance will have a whole community of fungi and bacteria growing on it. Each fungi or bacteria is distinct and produces a characteristic colony when grown in pure culture. The isolation of pure colonies of microorganisms is essential for a microbiological procedure. The purpose of knowing how to perform pure culture techniques is to isolate single organisms from mixed populations. There are many and often complex isolation techniques which can be quite effective in yielding only the desired fungi and bacteria (a biocontrol agent). Isolation techniques are divided into two broad categories: (1) direct and (2) selective and both are routinely used in mycology bacteriology laboratories and can be further divided into a number of subtypes. A. Direct isolation techniques Direct transfer (for fungi and bacteria): The term direct is applied to techniques involving the simple transfer of a fungus/bacterium from its natural habitat to a pure culture in the laboratory. This is done by placing a piece of the habitat or substrate under a dissecting microscope so that the fungal/ bacterial growth is easily visible. Moist chambers (for fungi): Direct isolation of fungi is often more effective if the natural substrate is kept moist for at least a week to allow moulds to grow and sporulate. The easiest method uses a container called a moist chamber. Placing decayed material in a moist chamber will often result in abundant sporulation of the guilty organism in the affected area. Moist containers hold a material such as cotton, paper, cloth, sterile sand/soil or peat moss that can be kept moist for several weeks. Direct plating: It is often most convenient to place material of interest directly on a nutrient agar medium. This technique encourages rapidly spreading microorganisms at the expense of other fungi but is widely used, nevertheless. 130

156 Streak plat technique (for bacteria): The most common technique for obtaining pure isolates of bacteria is the streaking of culture material on to agar plates. There are many different kinds of media used in the laboratory. The material to be tested is streaked on the surface of the media and isolated colonies are found. These organisms must be separated into pure colonies so further identification is possible. The test material is streaked so that individual organisms are spread across the plate. This allows each organism to grow and yield a pure colony. Dilution plating (for bacteria and fungi): This technique is used to study soil microorganism or the material, which are hard to study in nature. Dilutions are frequently used in studies on soil fungi. It is probably the most common method in this area of study. B. Selective isolation technique Baits: Many moulds have specific nutrient requirements and are specialized in using material that other fungi use with difficulty or not at all. This offers an advantage for the isolation of fungi by presenting a particular substance to the environment for colonization and then recovering it for isolation of the fungi that occupied it. The bait can be submerged in a particular habitat in nature or in a moist chamber. Selective nutrients: Essentially, it is the same technique as the baiting methods discussed above. It differs only in that the substance to be sampled is added to the bait rather than vice versa. For example, to isolate moulds that can utilize cellulose a medium using cellulose in place of sucrose is required Mass multiplication of fungal antagonist, Trichoderma Solid state fermentation Take 150 g of substrate (full grains of sorghum or pearl millet) in conical flasks or polypropylene bags heat, seal and autoclave. Inoculate the autoclaved substrate with Trichoderma mother culture under laminar flow/isolation chamber and incubate at room temperature. Solid substrate after 7-10 days can be mixed with sand or FYM/compost (1:2) and applied as soil treatment. Liquid state fermentation Czapek Dox broth or V8 broth or Richards broth or PDA broth or molasses-yeast or molasses-soy or jaggery-soy broth medium are good for liquid fermentation. Mix the ingredients of the respective medium in conical flasks/glass bottles and autoclave. After cooling to room temperature, inoculate with mycelia and spore discs from mother culture. The flasks are kept stationary or on a rotary shaker at rpm for 3-5 days. Keep in a stationary stage for 1-2 days and the mycelial mat and spore thus obtained is used to make the formulation after drying or directly mixing with talc powder. 131

157 Figure 9.6 Mass production of fungal antagonist Trichoderma spp Mass multiplication of Beauveria, Nomuraea and Metarhizium Place 250 g wheat bran in a polypropylene bag and add an equal amount of distilled water containing 10 g molasses and 1.25 g yeast extract. Autoclave the medium, and after cooling, inoculate the mother culture discs to the polyethylene bags under laminar flow and incubate at 25 C. Mycelial growth develops over the next 3 days. After 6 days of inoculation, the substrate with mycelial growth is transferred to sterilized plastic trays and covered tightly with a polythene sheet under laminar flow. The sporulation starts from 6 to 8 days, and is then refrigerated for a week. The medium is dried under the shade and the spores harvested by sieving are used to make the formulation or application, otherwise stored in the refrigerator Formulation of fungal biopesticides The biomass is added to carrier material like talc, diatomaceous earth-molasses, pyrax, wheat bran, kolin, sodium alginate, Ca Cl2, Vermiculite, Gypsum or peat, in a ratio of 1:2. Carboxy Methyl Cellulose (CMC) or gum Arabic is 0.5 per cent. In entomopathogenic fungi biomass, Tween 80 can also be 0.02 or 0.05 per cent. The addition of wetting agents like casine, gelatin, lactose, NaCl, Triton-X-100 or soap, helps 132

158 in the adjustment of the desired activity level while adhesives like molasses and methylcellulose, help reduce run-off while spraying Mass multiplication of Bacillus/Pseudomonas One hundred millilitre of Kings B broth medium for Pseudomonas sp. and nutrient broth medium for Bacillus sp. shall be autoclaved. Then the medium shall be inoculated with respective bacterial culture and incubated at room temperature on rotary shaker at 100 rpm for 48 h. Talc-based formulations can be prepared for each culture and 250 g of sterilized talc powder, 0.5 per cent CMC and 3.5 g of calcium carbonate should be added to 100 ml of bacterial broth. This is mixed thoroughly and dried in a shade. Seeds are coated in talcbased formulation at 10 gm per kg of seeds and shade-dried for two hours before use. The bacteria require a specific liquid media like oat meal broth for Bt and KB broth medium for Pf. The bacteria are mostly multiplied in liquid media and kept on a shaker incubator at 28 C- 30 C at 200 rpm. Figure 9.7 Mass production of Mycopathogenic Bacteria, Pseudomonas spp. 133

159 NPV (HaNPV and SINPV) mass production The Baculovirus group have a very narrow host range and generally infest the larvae of crop pests. The research aimed at insect pest control is, therefore, confined to nuclear polyhedrosis viruses (NPVs) and granulosis viruses (GVs). The NPV is a nucleic acid (double-stranded, circular DNA) enclosed in a protein matrix, and hence is called a polyhedral occlusion body (POB). The NPV infects the nucleus of the cell and multiplies within the nucleus. In India, extensive research has been conducted on the use of NPVs for tackling two major pests, namely Spodoptera litura and Helicoverpa armigera. Nuclear Polyhedrosis Viruses like HaNPV, SINPV are increasingly being used as alternatives to chemicals. These viruses have distinct advantages over other methods of pest control. NPVs are virulent pathogens of insect characterized by the polyhedral occlusion bodies (POB). These viruses are highly specific and do not affect beneficial insects like parasitoids and predators, and are safe to fish, birds, animals and humans. Considering the usefulness of NPVs, demand among farmers for these bioagents is growing. Spodoptera litura (Tobacco caterpillar) is a polyphageous pest which causes serious harm to tobacco nurseries. It is also a sporadic pest in cauliflower, cabbage, castor, cotton, groundnut, potato and lucerne crops. The SlNPV virus is specific and infects only Tobacco caterpillar. The NPV can be successfully multiplied on the Tobacco caterpillar and the viral extraction can be applied in the field to control the caterpillar. For continuous production of SINPV, it is necessary to rear Tobacco caterpillar larvae continuously in laboratory conditions. Gram pod borer (Helicoverpa armigera) is widely distributed and infests/damages a variety of cultivated and wild plants throughout its distribution range. It is a serious pest in commercial crops like cotton, pulses like red gram and Bengal gram, vegetables like tomato, bhendi and dolichos bean, oilseeds like sunflower, soybean and safflower, and cereals like sorghum and maize. HaNPV is a highly infective microbial biopesticide and can be used to control gram pod borer. It is derived from naturally diseased, or produced under laboratory conditions from artificially infected, larvae of gram pod borer. The mass production of HaNPV and SlNPV involves the following steps: Rearing of adult gram pod borer and Tobacco caterpillar for mass production of eggs. Rearing larvae of the above species either on host plants such as chickpea and castor under semi-natural conditions or on synthetic diet in laboratory conditions. Only the latter is considered in the model for large-scale commercial production of NPV. Inoculation of HaNPV and SlNPV into the larvae of gram pod borer and Tobacco caterpillar, respectively, through incorporation in diet, for mass multiplication of viruses and extraction of polyhedral occlusion bodies (POBs) from the diseased larvae, which are used as biopesticide on crop plants. Inoculation of larvae with HaNPV and SlNPV: For HaNPV and SlNPV production, the prepared synthetic diet is poured at 4 g/cell in the multicavity trays and the diet surface is uniformly sprayed with virus prepared in distilled sterilized water at 18 x 10 6 POBs/ml. Eighty per cent of the total 5-7 day-old larvae are utilized for HaNPV and SlNPV production. 134

160 The trays are incubated at 26 C for seven days. In case of virus-infected larval trays, the diseased larvae die after attaining maximum size, where the dead caterpillar has 2-6 billion polyhedral occlusion bodies (POB) in terms of larval equivalent (LE). One LE of H.armiegera NPV = 6 x 10 9 POBs; 1 LE of S. litura = 2 x 10 9 POBs. The larval death occurs with typical symptoms of the head-down position. Processing the dead infected larvae: The dead larvae should be collected and putrefied for 5 days in a china clay pot, covered properly with a lid. The larvae are kept moist by sprinkling water occasionally. After 5 days, the entire biomass is macerated thoroughly to obtain a homogenous content. This will release polyhedra from the putrefied tissue. The macerated content is diluted in a little water and sieved through fine cotton cloth. The filtrate contains polyhedra. A little water is sprinkled 2-3 times over the putrefied tissue to extract the residual polyhedral. For purification, the filtrate is centrifuged at rpm for 10 minutes and the supernatant containing the POBs is decanted. The tissue precipitation is discarded Isolation and mass production of entomopathogenic nematodes Nematodes causing disease within an insect are referred to as entomopathogenic nematodes (EPNs) and have the ability to kill insects. Nematode parasites of insects have been known since the 17th century, but it was only in the 1930s that serious consideration was given to using a nematode for insect control. Generally, several EPNs infect a single insect host. Infective juvenile nematodes penetrate the insect s body cavity either through natural body openings such as the mouth, anus, genital pore or breathing pore, or by breaking the outer cuticle of the insect. Heterorhabditids do this using a dorsal tooth or hook. Once inside the body cavity of the host, the infective juveniles (IJs) release bacteria that live symbiotically within the EPN s gut, but do not harm the nematode. The nematodebacterium relationship is highly specific only Xenorhabdus spp. bacteria coexist with steinernematids and only photorhabdus bacteria coexist with heterorhabditids. Once released into the host, the bacteria multiply quickly, and under optimal conditions cause the host to die within 24 to 48 hours. Isolation of entomopathogenic nematodes: Use hand shovel to collect a soil sample. Fill a small plastic sealable container with the soil sample till about the half-way mark. Then, drop about 5 or 6 wax worm larvae into the plastic container and allow it to incubate at room temperature for one week. After the incubation period, remove the wax worms from the soil container and place these in a small petri dish lined with a sheet of filter paper. Moisten the filter paper with a few drops of distilled water. Half fill a larger petri dish with distilled water and place the smaller petri dish in it. Incubate the dishes for one week. After a week, the nematodes emerge and are visible in the water of the larger petri dish. 135

161 Remove the small petri dish. Pour the nematode solution from the large petri dish into the large sealable bottle. Fill the large sealable bottle with distilled water and refrigerate for one week. This allows the nematodes to reproduce. Preparing the white trap Step 1: Place a watch glass (52 mm) with its convex side up in a large petri dish (110 x 25 mm). Place a filter paper (Whatman#1, 90 mm diameter) on the watch glass so that the lower edge of the filter paper touches the bottom of the dish. Step 2: Pour distilled water over the filter paper and let it spread on the petri dish. The level of the water should be maintained so that it is always in contact with the edges of the filter paper only. Step 3: Place wax moth cadavers on top of the watch glass. Cover the watch glass with the top cover of the petri dish, taking care that a sufficient gap is maintained between the cadavers and the top cover. Figure 9.8 White trap for EPN isolation Step 4: Place the white trap in the incubator maintained at 25±1 C and observe daily for nematode activity inside the body of the larvae. Nematodes (especially infective dauers) will start emerging out of the cadavers after exhausting the host and move to the bottom of the petri dish containing water. 136

162 Figure 9.9 Emergence of EPNs from infected larvae Step 5: Decant water with the nematodes daily into a beaker and replace with fresh distilled water. Step 6: Clean harvested nematodes repeatedly by washing with distilled water and store with 0.1 per cent formalin solution in a conical flask. The harvested nematodes should be further infected to a fresh culture of wax moth to confirm the authenticity of EPN (Koch s postulate) infection and to obtain a pure strain. Production and formulation: Entomopathogenic nematodes are currently mass-produced by different methods either in vivo or in vitro (solid and liquid culture). In vivo production is, arguably, the most appropriate technology for grower cooperatives and developing countries where labour is not expensive. In vivo production is a simple process of culturing specific EPNs in live insect hosts and requires less capital and technical expertise. In vivo production systems are based on the White trap, and take advantage of the natural migration of the IJ from the host cadaver upon emergence. The most used insect host used for in vivo production is the last instar of the greater wax moth (Galleria melonella) because of its high susceptibility to most nematodes, ease in rearing, wide availability and ability to produce high yields. Insect hosts are inoculated on a dish or tray lined with absorbent paper. The infected insects are transferred to White traps after a period of 2 to 5 days. Formulated EPNs can be stored for 2 to 7 months depending on the nematode species and storage media and conditions. Unlike other microbial control agents such as fungi, bacteria and virus, EPNs do not have a fully dormant resting stage and use their limited energy during storage. The quality of the nematode product can be determined by nematode virulence and viability assays, age and the ratio of viable to non-viable nematodes. 9.5 Conclusion The importation, augmentation and conservation of natural enemies constitute the three basic approaches to biological control of insect pests. Specific techniques within these approaches are constantly being developed and adapted to meet the changing needs of pest management. Improvements in rearing and releasing techniques and genetic improvement of natural enemies have resulted in more effective augmentation programmes. 137

163 Sustainable agriculture aims to promote technically sound, economically environment-friendly and socially acceptable use of natural resources. viable, Emphasis has been placed on the importance of pest management involving a sound knowledge of ecology of the key pests. An important component of pest management is the biological suppression of pests employing parasitoids, predators and pathogens such as viruses, fungi, bacteria, protozoa and nematodes. These organisms, if conserved and augmented, can keep some of the pests within economic injury levels. Pest management experience in agroecosystems indicates a need for the balanced use of natural resources besides controlled use of agrochemicals through IPM. As such, biological control appears to be a promising component of IPM, being ecologically safe, compatible with the other components and sustainable in the changing scenario of global agriculture. 138

164 10 Farmer Field School Approach in Dissemination of IPM Strategies 10.1 Introduction Chemical pesticides are expensive and potentially injurious to crops, environment and human health. The farmer field school approach promotes the use of IPM technology involving both trainers and trainees. It has the following main objectives: 1. Help farmers adopt IPM and provide them on-the-spot guidance for adoption. 2. To provide follow-up for a sufficiently long period of time to ensure full integration of the new agricultural technology in the farming system. This is important because farmers can abandon an adopted innovation. 3. Training programmes become particularly important as the incremental gains in productivity are achieved by adopting 'second-generation technologies' (such as better fertilizer incorporation technologies and integrated pest management) that are more knowledge-intensive and location-specific than the modern seed-fertilizer technology that was characteristic of the Green Revolution. 4. Furthermore, according to the International Rice Research Institute (IRRI), "Farmers who have the ability to learn about the new technologies discriminate among technologies offered to them by the research system, adapt the technologies to their particular environmental conditions and provide supervision of inputs to ensure the appropriate application of the technology." (Pingali et al., 1990). 5. This assessment of the capacity of farmers to learn and apply what they learn was drastically at odds with the assumption of Green Revolution extension education systems that traditional farmers required a complete refitting of their practices to become modern. The time for a new approach to farmer education had arrived in the form of a farmers participatory training method, namely Farmer Field School Genesis of Farmer Field School (FFS) The FAO regional IPM programme for Asia faced the following problems in the late 1980s. 1. Pest resurgence and resistance caused by the indiscriminate use of insecticides posed an immediate threat to the gains of the Green Revolution. 2. Research demonstrated the viability of biological control of major rice pests, but such an approach required a broader understanding on the part of farmers of the ecological principles underlying the rice field agroecosystem. 3. Green Revolution extension approaches were actually de-skilling farmers, not improving their expertise, necessitating new approaches for educating farmers. 139

165 FFS development in the Philippines The first steps towards the IPM farmer field school approach were taken in the Philippines with the initiation of a farmer training programme lasting for five consecutive planting seasons from 1978 through The training tried new methods to help farmers learn IPM. Farmers were trained in small groups and encouraged to be active in discussions during training sessions. The training tried an extended schedule of over three months with weekly two-hour sessions. Hands-on field practice was favoured rather than expensive material, theory or lectures. Follow-up sessions by extension workers in farmers' fields were encouraged. The Philippine farmer training effort made important innovations that were eventually incorporated in the IPM farmer field school in Indonesia. The rice field was used as a classroom with CROP AS A TEACHER. The ballot box pre-test was developed as a field-based diagnostic test to determine learners' needs. Live samples were used for learning rather than photographs or drawings. Methodology shifted from lectures to structured experiences and analysis of field conditions. Experiments in season-long training found that IPM training needed to be of longer duration. The approach posited that the most interesting and determinant element in the rice field was the farmer, not the insects Indonesia and Farmer Field Schools The approach to farmer education named the rice IPM farmer field school incorporated the lessons from the Philippines' experience in farmer IPM training, and was implemented first in Indonesia. The first FFS was conducted in the 1989/90 rainy season. In a few years, the approach was being used throughout the region. Field schools give small farmers practical experience in ecology and agroecosystem analysis, providing the tools needed to practise IPM in their own fields. The FFS also provides a natural starting point for farmer innovation, covering the entire range of issues relating to crop and agroecosystem management Principles of FFS The FFS approach is based on four IPM principles and practices. The principles provide a guide to the farmers role in an FFS and form the working definition of IPM for the FAO community IPM programme (see Figure 10.1 and Table 10.1). 140

166 Figure 10.1 Farmer Field School process Table 10.1 Principles and practices of Farmer Field Schools Principles Practices 1. Grow a healthy crop Apply good agronomic practices and understand plant biology. This should help FFS alumni to optimize yields and grow plants that can withstand disease and pest infestations. 2. Conserve natural enemies 3. Conduct regular field observations FFS alumni reduce insecticide use. To do this, they need to understand insect population dynamics and rice field ecology. IPM requires of farmers the ability to regularly observe, analyse and take informed decisions based on conditions of their agroecosystems. 4. Become IPM experts Farmers are better positioned to take decisions relevant to their fields than agricultural specialists in a distant city. Hence, FFS alumni should be able to apply IPM in their fields and also help others to do so Fundamental elements of Farmer Field School A Farmer Field School (FFS) consists of people with a common interest, who get together on a regular basis to study the how and why of a particular topic. The topics covered can vary considerably from IPM, organic agriculture, animal husbandry and soil husbandry, to income-generating activities such as handicrafts. The FFS is particularly adapted to field study requiring specific hands-on management skills and conceptual understanding. The following is a list of elements of successful FFS programmes: The group: A group of people with a common interest form the core of the FFS. The group may have men and women together or be separated by gender, depending on culture and topic. The group could be established already, such as a self-help, women s or youth group. The FFS tends to strengthen existing groups or may lead to the formation of new groups. The field: The FFS is about practical, hands-on topics. In the FFS, the field is the teacher and it provides most of the training material like plants, pests and real problems. Any new language learned in the course of study can be applied directly to real objects and local 141

167 names can be used and agreed on. Farmers are usually much more comfortable in field situations than in classrooms. In most cases, communities can provide a study site with a shaded area for follow-up discussions. The facilitator: Each FFS needs a technically competent facilitator to lead members through the hands-on exercises. There is no lecturing, so the facilitator can be an extension officer or a Farmer Field School graduate. In most programmes, the key objective is to move towards farmer facilitators who are often better facilitators than outside extension staff as they know the community, speak a similar language, are locally recognized as colleagues and know the area well. The curriculum: The FFS curriculum follows the natural cycle of its subject, be it crop, animal, soil or handicraft. For example, the cycle may be seed to seed or egg to egg. This approach allows all aspects of the subject to be covered, in parallel with the events on the FFS member field. The programme leader: Most FFS programmes exist within a larger programme, run by the government or a civil society organization. It is essential to have a good programme leader, who can support the training of facilitators, get material organized for the field, solve problems in participatory ways and nurture field staff facilitators. This person needs to keep a close watch on the FFS for potential technical or human relations problems. He or she is also the person likely to be responsible for monitoring and evaluation. The programme leader must be a good leader and an empowering person. He or she is the key to successful programme development and needs support and training to develop the necessary skills FFS training methodologies and approaches The FFS approach featured several new departures from earlier IPM farmer education models. These include season-long training for farmers, field experiments, a focus on plant biology and agronomic issues, a new method for agroecosystem analysis, inclusion of human (group) dynamics activities and a learning approach stressing participatory discovery learning. The basics of FFS training methodologies and approaches are: Season-long training, covering all stages of the crop from seed to seed. Participants meet on a regular basis to observe and analyse the dynamics of the field ecology, including population dynamics of crop pests and their natural enemies during various stages of the crop growth, over the full season. The training is fully field-oriented, participatory and discovery-based (i.e. learning by doing). The primary learning material is the field. The FFS uses field studies as a learning method. Simple experiments such as comparison between IPM and farmer practice (conventional practice) and study on plant compensation are usually conducted by the group. The training aims at teaching science to farmers in their own fields. The FFS uses a minimum amount of lecturing. Most concepts and skills are taught through interesting and hands-on structured learning activities run by the facilitator. Learning skills is more efficient this way. It also frees the facilitator from the burden of lecturing and allows farmers to become facilitators themselves who repeat the 142

168 facilitation process of hands-on activities. The basis for the training approach is non-formal education, itself a learner-centred discovery process. The training curriculum is based on local needs. What is relevant and meaningful, is decided by the farmers Empowering farmers to solve live problems actively by fostering participation, selfconfidence, dialogue, joint decision-making and self-determination. FFS learning is an evolutionary process and characterized by free and open communication, confrontation, acceptance, respect and the right to make mistakes. Working in small groups and enabling cooperative approaches Training objectives To empower farmers to take economical crop management decisions through weekly Agroecosystem Analysis (AESA), insect zoo studies, simple experiments on plant compensation studies, nitrogen application studies, predation experiments and natural parasitization of lepidopteron insect pest eggs. Figure 10.2 Plant compensation studies in FFS FFS curriculum development FFS curriculum development is based on the following nine principles: 1. Technical content should lead towards a better understanding of the ecology. 2. Technical content should enable farmers to make their own decisions. 3. Technical content should be relevant to local needs and conditions. 4. Learning process should be experiential discovery-based. 5. Learning process should be non-hierarchical, a partnership between trainers and trainees. 6. Learning process should focus on quality not quantity. 7. Organization and management should have decentralized responsibilities. 8. Organization and management should involve collaboration among different organizations 9. Organization and management should make use of existing resources as far as possible. 143

169 Action plan Principle FFS topic/session Training methods What has to be done 1. Technical content should lead towards better understanding of ecology. Agroecosystem concept Field exercise followed by class room activity. Farmers divided into small groups. Pre-seasonal activity 2. Technical content should enable farmers to make their own decisions. Agroecosystem analysis, ecological engineering Weekly field observation, drawing, discussion and presentations. Insect zoo Conduct AESA during different crop stages. 3. Technical content should be relevant to local needs and conditions. 1. Critical practices 2. Critical inputs 1. Baseline survey 2. Brief presentation followed by discussion. Pre-seasonal activity - Strategy to address production gaps through outcome of baseline survey, selection of seed, seed treatment with biofungicides, land preparation, in situ moisture conservation. 4. Learning process should be experiential discovery based. Short-term experiments Action research Seed germination test, Water holding capacity, effect of chemical pesticides on crop defenders, insect zoo, predation 5. Learning process should be nonhierarchical, a partnership between trainers and trainees. Group dynamics exercises Active participation in team-building exercises, problem solving. Leadership development and attitudinal. Exercise on group dynamics (games): 1. Water brigade 2. Longest line 3. Tower building and 4. Broken squares 5. Drawing without lifting pen 6. Learning process should focus on quality not quantity. Training strategy should address 2/3 production gaps. Simple to complex experiments 1. Soil & water test 2. Seed germination test. 3. Ecological engineering 7. Organization and management should have decentralized responsibilities. Field observation and monitoring for insect pests and diseases. Dividing farmers in smaller groups and exercise by each group. 1. Agroecosystem analysis 2. Monitoring for pests and decision-making as individuals/smaller groups 8. Organization and management should have collaboration among different organizations. Good agricultural practices for reducing cost of cultivation. Market linkage and intelligence. Workshop Extension agents may organize pre-seasonal workshop involving scientists in planning and training. E.g. soil and water testing, valueaddition and market linkages. 9. Organization and management should make use of existing resources as far as possible. Indigenous Technical Knowledge (ITKs), low-cost and no- cost technologies. Resynthesis of technology. 1. Inter-crop, border crop, ecological engineering 2. Preparation of neem seed kernel extract for insect pest control 144

170 FFS curriculum time matrix The FFS curriculum is flexible and divided into three major parts based on time allocation. Weekly FFS sessions range from 2 to 5 hours, based on the local situation and famers interest. Figure 10.3 Some core topics of FFS in FFS curriculum matrix AESA & insect zoo Special topics Group dynamic Source: i. Science and farmers: a. Science and farmers deals with AESA, simple experiments to season-long experiments (e.g. seed germination test to plant compensation studies, insect zoo studies) b. Special Topic(s) addresses technical and local issues of that week (e.g. sucking pest problem, nutritional deficiency, wilt, root rots of that week, institutional credit, foot and mouth disease of cattle). Fifty per cent time may be allotted to Science and Farmers. Figure 10.4 Agroecosystem analysis chart 145

171 ii. Human (group) dynamics and team building To sustain the farmers interest, simulation games and ice-breaker sessions are also organized. The games can be related to team-building, problem-solving and resource management. Thirty per cent of time should be allocated for Human Dynamics. Figure 10.5 Team-building exercise (Warrior brigade) iii. Organization and management FFS is a learner-centred, discovery-based and non-formal education (adult learning) approach, using decentralized responsibility, involving farmers in the selection of training content, learning on their own and evaluating their learning. Twenty per cent time should be allotted to Organization & Management. 146

172 Figure 10.6 Share of different topics in FFS curriculum 1.Science & farmers, time-50% (Agro Eco-System Analysis 2. Group dynamics & team building, time-30% Insect zoo studies 3. Organization, management & field day time-20% FFS CURRICULUM MATRIX Science & farmers Group dynamics Organization & management 147

173 List of short studies to be conducted 1. Exposure of pesticides during handling (mixing and spraying) 2. Level of yearly exposure to pesticides 3. Signs and symptoms 4. Ecological function of organisms (Food web) 5. Agroecosystem concept 6. Seed germination test 7. Roots and plant vessels 8. Effect of pesticides spray on defenders 9. Exercise on diseases 10. Gender division of labour and decision-making matrix 11. What is this? What is that? List of group dynamics exercises to be conducted in FFS 1. Getting To Know Each Other (Dyads) 2. Titanic 3. Animal Sounds 4. Natural Enemies, Pest and Diseases 5. Problem Solving Activity 1 6. No Lifting of Pen Drawing 7. The Longest Line 8. Battle of the Sports 9. Block of Ice 10. Building Towers 11. Winner Takes All 12. List As Many As You Can 13. Water Brigade 10.6 Case study: Tentative schedule of FFS activities The weekly schedule of activities is designed to cover the entire season for the selected crop (i.e. seed to seed). Accordingly, the weekly schedule for a week FFS session for rice crop is worked out. It may be flexible to adjust the content and schedule to local conditions, file problems and farmers interests. This schedule also incorporates important innovations in training efforts by Philippines farmers. The weekly schedule of activities for rice-ffs is as follows: 148

174 Pre-FFS (pre-season) Prepare seed-bed and seedlings, sufficient for 1 ha to be ready in time for the first FFS session. Meet the farmers at the FFS learning field site for briefing about FFS and register participants. Be sure to clarify all obligations of FFS farmers. Arrange 0.50 acres (2,000 m²) as the study field, easily accessible by the FFS farmers. The seed germination test, seed treatment, collection of soil samples and other methods may be demonstrated to farmers. During FFS (season) Week 1: Week 2: Week 3: Week 4: Week 5: Week 6: Week 7: Week 8: Week 9: Week 10: Week 11: Week 12: Week 13: Post FFS Introduction, Ballot box pre-evaluation test and planting of study field by FFS farmers and facilitators Food web and Ecosystem concept, Group Dynamics (Team building exercise) Agroecosystem Analysis (AESA) for decision-making, predators, Pest: Defender ratio AESA, Group Dynamics (G.D), Root and Plant Vessels and Pesticides AESA, G.D, Primodial Development/maximum tillering and fertilization AESA, G.D, exposure of pesticide and toxicity AESA,G.D, Rats or other topic AESA, G.D, Diseases or other topic AESA, G.D, Insect Zoo, life cycles: parasites, predators, stem borer, BPH and leaf folders AESA, G.D, Disease management: Blast, sheath blight, etc. AESA, G.D or other topic AESA, G.D, Planning for field day Post-evaluation test (Ballot box), any other topic based on local problem Inform Pre- and Post-evaluation test marks to FFS farmers. Discussion on followup action Typical FFS session The duration of each FFS day will be 4-5 hours, preferably from 8 a.m. to 1 p.m a.m. Review of previous week s activities, briefing on the day s activity 8.30 a.m. Field observation on agroecosystem 9.45 a.m. Short tea break a.m. Energizer or team-building exercise a.m. Begin agroecosystem analysis, drawing and discuss, management decisions a.m. Each team presents results and the group arrives consensus on management needs for the next week p.m. Special topic 1.00 p.m. Review of the day, planning for next week, closure 149

175 10.7 Conclusion The IPM farmer field school has become the model approach for farmer education in Asia and many parts of Africa and Latin America. The approach has been used with a wide range of crops including rice, cotton, tea, coffee, cacao, pepper, vegetables, small grains and legumes. The FFS has been effective in involving a wide range of people in the learning process, from schoolchildren to persons with disabilities. Farmers across Asia have responded enthusiastically to IPM FFSs. Some farmers are motivated by the reduced costs and risks through the application of ecological principles to crop management. Some are intellectually stimulated and excited by the experience of designing and carrying out their own experiments. For others, the main attraction is the group interaction, discussion and debate that are an important part of FFS. The most striking confirmation of this enthusiasm has been the spontaneous appearance of the farmer-tofarmer FFS where FFS graduates organize a season-long FFS for other farmers. The FFS approach thus plays an important role in the dissemination of IPM strategies. 150

176 11 Summary and Way Forward 11.1 Introduction Pest management evolved through various stages, starting from the discovery of the insecticidal properties of DDT in 1939 and heavy reliance on chemical pesticide strategies to Economic Threshold Level (ETL)-based IPM and Agroecosystem Analysis (AESA)-based IPM. The evolution of IPM was an acknowledgement that pests can never be controlled but need to be managed, and that too not with a single measure but by multiples strategies based on factors such as the environment, farm economics and social and cultural aspects. Field-level implementation of IPM for various crops is not yet satisfactory in developing countries Information gaps in IPM There are various gaps between the information that farmers have and what they actually need. Research gap: There are some occasions when a new pest emerges in an agroecosystem, either through invasion from foreign countries or through secondary pest replacement mechanism. At those times there may not be sufficient research findings on management strategies for the new pest. This situation necessitates the research work by scientific institutions to develop newer strategies for the management of the pest. Synthesis or interpretation gap: Research has to be synthesized as a module and validated in the field to prove its effectiveness in the field. Dissemination gap: IPM dissemination requires a strong extension system after the synthesis and validation, and the FFS method is best suited for this. The facilitator/extension functionary also needs to be trained thoroughly in the IPM module. Reception gap: Despite its soundness, feasibility and economic viability, the technology may not be received properly by farmers at times due to social, cultural and other reasons. 151

177 Figure 11.1 Different gaps in transfer of information from laboratory to land 11.3 Decision model in IPM IPM is the intelligent selection and adoption of a suitable pest management technique and is not a single technology to be implemented as a package. The selection of an IPM method by the farmer depends on a variety of factors such as: Pest problem: The type of pests and the extent of damage caused. Control options: A variety of options may be suitable for a specific pest. The cost, availability and effectiveness of the treatment are major factors in deciding the control option. Farmer perception: The farmers perception of the pest situation is important in deciding the control option selected. If farmers perceive the presence of even a small number of pests as a serious threat, this will result in the use of costly IPM options. Farmer objective and attitude: This includes the monetary goal and attitude to financial risks, health hazards and community value, among others. 152

178 Figure 11.2 The process of decision-making in IPM 11.4 Validation of IPM technologies Validation of IPM refers to the combination of various scientific tenchologies knitted together as an IPM module for testing in a real field situation. As IPM is a multidisciplinary, multiorganizational and multilocational participatory approach, the involvement of all stakeholders, including farmers and field technicians, should be ensured. The IPM validation methodology encompasses the following: i. Analysis of the context and definition of pest problems: It is necessary to survey the selected area for detailed information on crops, varieties, crop production and protection practices. This should be followed by analysis of the cropping system, pest problems and their characteristics. ii. Formulation of IPM modules: IPM modules are synthesized on the basis of the information available on management measures for key pests in the area. Farmer 153

179 practice should also be kept in mind while synthesizing the IPM module, which should be eco- and farmer-friendly. iii. Selection of farmers and collection of baseline information: The selection of farmers for an IPM programme, which is new to them, is not easy and needs sustained persuasion to convince them of its benefits. Community participation is necessary for a successful IPM programme. Once successful with a few farmers, the programme is more likely to attract others in succeeding years. iv. Orientation phase: Orientation involves interaction with farmers about crops, varieties, pest problems, production and protection practices and constraints to raising crop yields. The use of audiovisual aids, charts, photographs and pamphlets helps attracts the attention of farmers towards improved crop varieties, modern production practices, key pests, natural enemies of pests and IPM practices to be validated. Farmers are told about the why, what, when and how of IPM in relation to existing practices and provided demonstrations of new IPM techniques, particularly pheromone traps/light traps and biocontrol inputs. v. Farmer Field School (FFS): Once farmers adopt the programme, it is crucial to have regular interaction with them through FFS at least once a week during the crop season. The day, time and venue for the FFS are pre-fixed. The offices of village governing bodies or local schools are the most appropriate as these offer facilities to explain IPM with presentations using diagnostic charts, photographs and written instructions. Key farmers are encouraged to lead the FFS under the supervision of scientists/field technicians. The crop fields are treated as classrooms to monitor the crop, pests and natural enemies and take appropriate action. vi. Provision of critical IPM inputs: The availability of critical inputs like seeds, biopesticides, pheromone traps, good quality chemical pesticides, application equipment and protective clothing for the safe use of pesticides should be ensured. Small and marginal farmers are found inclined to adopt new practices if critical inputs are available. vii. Collection of data and impact analysis: A data sheet and the standard impact assessment format are used to collect data, which is analysed to assess the impact of IPM on crop yield, biodiversity and profitability. Simple, farmer-friendly and costeffective IPM modules are selected and recommended for dissemination in similar areas Promotion of validated IPM technologies It is necessary to have a dissemination strategy for the horizontal spread of IPM technologies in wider areas with crop/pest problems similar to the location where the IPM technology was validated. The dissemination strategy has the following essential components: 1. Community participation: Success depends on the active participation of farmers and village institutions. The participation and motivation of women, facilitates adoption. An area-wide approach is necessary to produce visible impact. 2. Training and education: As IPM is knowledge-intensive, the development of human resources is important. This includes training to make master trainers, extension personnel, field technicians and farmers fully aware of IPM, prevention methodologies, pest monitoring and management, and decision-making tools. Dealers/retailers of 154

180 chemical pesticides/biopesticides also need appropriate training. For participating farmers, regular training through the FFS is mandatory. 3. Public-private partnership: The participation of research organizations and nongovernmental organizations and industries, along with farmers, makes IPM effective. 4. Availability of IPM inputs: The timely supply of critical inputs like seeds and good quality biocontrol agents as well as different biopesticides is crucial. Both public and private agencies should ensure the timely availability of critical IPM inputs to farmers. 5. Removal of obstacles: It is necessary to address the following key issues: i. Farmers perception that chemical pesticides are convenient to use and produce results quickly while holistic IPM is a complex method that demands elaborate planning needs to be changed. Adequate training and on-farm demonstration of the economic, social and environmental benefits of IPM can help change this perception. ii. Extensive use of broad-spectrum and extremely hazardous chemical pesticides may hamper the implementation of IPM. It is necessary to promote only targetspecific and less hazardous chemicals that can fit well in IPM. iii. Inadequate awareness among state and non-governmental functionaries about the potential of IPM should be addressed, and their active participation in IPM programmes encouraged Conclusion Integrated pest management has received far more attention than any other method of insect control. The term IPM encompasses a comprehensive long-term pest management strategy using an ecosystem-based approach that takes into account the economic, environmental and social consequences of pest control. IPM is based on the periodic monitoring of the pest population and using appropriate therapeutic or biological interventions. The success of IPM programmes has led to the creation of the FAO Global IPM facility. There has been a qualitative and quantitative change in the pest spectrum and pest control interventions over the past five decades. A systems approach to pest management, taking into account natural resources, biodiversity, landscape and environmental conservation would have immense benefits. There is a need for farming practices compatible with ecological systems by avoiding crops, cultivars and agronomic practices that help transform an insect species into a pest. Natural enemies should be promoted through reduced pesticide use and appropriate cropping practices. Molecular biology tools can help make pest management more effective, economic and friendly to the environment. 155

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190 13 Annexes Annex 1 IPM Practices for Different Crops I Wheat ii Maize iii Red gram iv Black gram and green gram v Castor vi Mustard/rapeseed vii Tomato viii Okra ix Brinjal x Cruciferous vegetable xi Cucurbitaceous crops xii Chillies/ capsicum xiii Apple xiv Citrus xv Banana xvi Grapes xvii Mango xviii Watermelon Note: Due to large size, this Annexure is not included in the published version of this training manual. It can be accessed online from: 165

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