PEST DAMAGE to U.S. agricultural

Transcription

1 Integrated Pest Management PEST DAMAGE to U.S. agricultural crops has been estimated to be 33 percent of the total crop production potential, which is a great loss of food and fiber that could be put to human use. Also, it is a huge economic loss. To reduce losses, carefully planned strategies must be employed to limit pest damage. Objective: Explain integrated pest management. Key Terms: abiotic bacteria biological control biotic causal agent chemical control clean culture cultural control disease triangle economic injury level economic threshold eradication fumigant fungi fungicides genetic control herbicides hyphae infectious diseases insecticides insects integrated pest management (IPM) key pest mechanical control mites miticides molluscicides mycelium nematocides nematodes noninfectious diseases parasitic plants pathogens pest pest population equilibrium pest resurgence pesticides pesticide resistance plant disease quarantine regulatory control rodenticides targeted pest trap crop viruses weeds Page 1

2 The Importance of Integrated Pest Management Integrated pest management (IPM) is an organized program in which the best management methods available are used to keep pest populations below the economic injury level. Also, IPM is used to avoid adverse effects to humans, wildlife, and the environment. IPM is a pest-control strategy that relies on multiple control practices. It establishes the amount of damage that will be tolerated before control actions are taken. The key to a successful IPM program is the use of a scout (the grower or a hired individual) who regularly monitors pest populations and crop conditions. The scout collects data about the pests that are causing damage, the pests current life stages, and if the pest population is increasing or decreasing. Knowing how to identify a key pest (a pest that occurs on a regular basis for a given crop) and its biological characteristics is important because the weakest link in each pest s biology must be found for successful pest management. An understanding of the crop s biology and its ecosystem is essential for successful IPM. The crop s ecosystem consists of the biotic and abiotic influences in its living environment. The biotic components are the living organisms, such as plants and animals. The abiotic components are nonliving factors, such as soil and water. IPM attempts to understand the influence of ecosystem manipulation on lowering pest populations. Pest population equilibrium occurs when the numbers of a pest stabilizes or remains steady. TYPES OF PESTS An understanding of the major pest groups and their biology is required to ensure success in reducing crop losses due to pests. A pest is a living organism that can cause injury or loss to a plant. Pests include insects, diseases, weeds, mites, nematodes, parasites, and animals. Insects Insects are a group of animals with an exoskeleton and three body parts. Most insects have six legs and four wings. At this time, more than 800,000 kinds of insects have been identified. Due to the ability to produce large numbers of offspring in a short time, insects can cause economic loss by feeding on horticultural crops. Insects have chewing or sucking mouthparts. Damage symptoms caused by chewing insects are leaf defo- FIGURE 1. Insects caused considerable damage to this corn plant. Page 2

3 liation, leaf mining, stem boring, and root feeding. Insects with sucking mouthparts produce distorted plant growth, leaf stippling, and leaf burn. As an insect grows from an egg to an adult, it passes through several growth stages called metamorphosis. There are two types of metamorphosis: incomplete and complete. Incomplete metamorphosis consists of three life stages: egg, nymph, and adult. As a nymph, the insect grows and passes through several instars between molts. Each time the insect molts or sheds its exoskeleton, it passes into the next instar. Complete metamorphosis consists of four life stages: egg, larva, pupa, and adult. The larva stage is the period when the insect grows. The pupa stage is a resting period where a dramatic morphological change from larva to adult occurs. Plant Diseases A plant disease is a disturbance to normal plant growth and development. Diseases are generally classified as infectious or noninfectious. Infectious diseases are caused by living organisms (bacteria, fungi, and viruses) that are often referred to as disease pathogens.an infectious disease can be spread to other plants. In contrast, noninfectious diseases are caused by environmental imbalances and cannot be spread to other plants. Examples of noninfectious disease include over watering, nutrient deficiencies, and air pollution damage. Plants are most susceptible to disease when under stress, which is usually associated with environmental factors. While the environmental condition itself may or may not cause a noninfectious disease, the stress it creates can reduce a plant s ability to fight off infectious disease. For instance, over watering can cause the death of root tissues, but it also weakens the plants defenses against soil-borne disease organisms. The occurrence and severity of infectious plant diseases is based on three factors. A susceptible plant or host must be present. The causal agent or organism that produces a disease must be present, and the environmental conditions conducive to the causal agent must occur. The relationship of these three factors is the disease triangle. Disease-control programs are designed to affect each or all of these factors. Fungi are a principal cause of plant disease. Fungi are eukaryotic organisms (organisms whose cells are organized into complex structures by internal membranes) that are members of the kingdom Fungi. They absorb nutrients from living or dead organisms, and their bodies consist of thread-like vegetative structures known as hyphae. When grouped together, hyphae is called mycelium. Fungi can reproduce FIGURE 2. The blight on this tomato is known as a fungus. (Courtesy, Jackie Mullen, Auburn University) Page 3

4 and cause disease by producing spores or mycelia. The fungus can produce spores asexually or sexually. Bacteria are one-celled microscopic organisms. Individual bacteria have a wide range of shapes. They are found in every Earth habitat and can enter a plant only through wounds or natural openings. Viruses are composed of nucleic acids surrounded by protein sheaths. They are capable of altering a plant s metabolism by affecting protein synthesis. Plant viruses are transmitted by seeds, insects, nematodes, fungi, and mechanical means. Viral diseases produce several symptoms including ring spots, stunting, malformations, and mosaics. A mosaic symptom is a leaf pattern of light and dark green color. Weeds Weeds are plants that are undesirable and are often considered out of place. Weeds compete with crops for growth essentials: space, nutrients, water, and light. They also harbor insect pests. Other Pests Plants suffer from a variety of other pests including mites, nematodes, parasitic plants, and mammals. Mites are small organisms with an exoskeleton, two body parts, and eight legs. Nematodes are tiny hair-like roundworms that feed on plant roots. They may live in the soil or water, within insects, or as plant or animal parasites. Nematodes are quite small and produce damage to plants by feeding on roots, stems, or leaf tissue. Some plants (e.g., dodder and mistletoe) are parasitic. Parasitic plants extract water and nutrients from other plants FIGURE 3. This out-of-place sunflower is robbing nutrients from nearby crop plants. FIGURE 4. Nematodes are extremely small pests that can destroy plant roots. (Courtesy, Frank Killebrew, Mississippi State University) Page 4

5 and give nothing in return. Mammals including deer, mice, rabbits, and voles cause severe physical damage to plants, which often causes plant death. ECONOMIC LOSSES The estimated pest damage to U.S. agricultural crops amounts to one-third of the total crop production potential. Methods are available to minimize or eliminate the losses that pests cause, but the goal of managing pest populations is to keep losses below a level where profit is reduced. The economic injury level is the point at which the cost of pest control equals the revenue loss caused by a pest. Economic injury level is determined by estimating the potential yield loss, the value of the crop, and the cost of treatment. The economic injury level clearly defines how much damage can be tolerated. The economic threshold is the number of insects per plant or the amount of damage to the plant that economically justifies the use of control measures. If a control is applied when a pest population reaches the economic threshold, the population will be suppressed before the economic injury level is reached. BENEFITS OF INTEGRATED PEST MANAGEMENT There are many benefits of integrated pest management (IPM) to agriculture and to the environment. These benefits help sustain the ability of the earth to meet the needs of an increasing human population. Benefits of IPM to the Agriculture Industry 1. Reduced pesticide costs Fewer pesticides are used with IPM. As a result, the cost of pesticide is reduced, and less equipment is needed. 2. Reduced application costs The cost of labor for pesticide application is reduced due to less time needed. 3. Less pesticide resistance Insects, weeds, and other pests will be less likely to develop pesticide resistance, which means that a pesticide is more effective when its use is required. Benefits of IPM to the Environment 1. Reduced contamination The environment suffers less degradation through the use of IPM. Pesticide residues do not build up in soil, water, and other natural resources. 2. Fewer residues on food Food products will have less pesticide residue with IPM, which reduces the chance of people contracting diseases associated with pesticides. Page 5

6 3. Improved human health IPM contributes to food products that promote good health. Cancer-causing residues from agricultural chemicals are present in smaller amounts or are not on food at all. COMPONENTS OF IPM The reason for using IPM methods of pest control and crop protection is that reliance on chemicals as the only means of pest control can lead to pest resistance, pest resurgence, and possible harmful effects to humans and the environment. IPM uses chemical and nonchemical control methods to help reduce losses from pests. Choosing which method or methods to use will depend on an accurate assessment of the problem as well as information about the crop, the field, and the type of management. IPM methods include biological, chemical, cultural, genetic, and mechanical control. Biological Control Biological control is the use of living organisms to reduce pest populations. These beneficial organisms are natural enemies of pests. They attach, live in, or infect pest hosts. Parasites, predators, and pathogens are all used as biological controls. Chemical Control Chemical control is an integral part of an IPM program and is the use of pesticides to reduce pest populations. Pesticide resistance is the ability of an organism to tolerate a lethal level of a pesticide. Pest resurgence refers to a pest s ability to repopulate after control measures have been eliminated or reduced. Pesticides are the most dangerous means of pest control in terms of risks to the environment and to humans. Even highly trained applicators must be extremely cautious when using pesticides. FIGURE 5. Using parasitic wasps to control pest populations is known as biological control. (Courtesy, Agricultural Research Service, USDA) FIGURE 6. Using chemicals to destroy pests is a form of chemical control. Page 6

7 Cultural Control Cultural control is used to make the crop environment unsuitable for pests to feed, live, or reproduce. In addition, cultural control helps to improve the crop s health. Examples of cultural controls include soil tillage, crop rotation, the adjustment of harvest or planting dates, irrigation schemes, variety selection, clean culture, and trap crops. Clean culture refers to any practice that removes the breeding or over-wintering sites of a pest. A trap crop is a susceptible crop planted to attract a pest to a localized area. After the pest arrives, the trap crop is destroyed or treated with a pesticide. Genetic Control Genetic control involves the use of genetically engineered organisms to fight pests. Plant breeders are constantly working to develop varieties and hybrids that are resistant to or tolerant of pests. Mechanical Control Mechanical control is used to physically remove or exclude pests. It includes hand destruction as well as the use of screens to keep out insects and traps to catch them. Federal and state governments have created laws that prevent the entry or spread of known pests into uninfested areas, which is referred to as regulatory control. Regulatory agencies also attempt to contain or eradicate certain types of pest infestations. The Plant Quarantine Act of 1912 provides for inspection at ports of entry. Plant or animal quarantines are implemented if shipments are infested with targeted pests. Quarantine is the isolation of pest-infested material. A targeted pest is a pest that, if introduced, poses a major economic threat. If a targeted pest becomes established, an eradication program will be started. Eradication means total removal or destruction of a pest, which is extremely difficult and expensive to administer. Pesticide Classes Using chemicals to manage pests and diseases is referred to as chemical control. Pesticides are the materials used to control pests. These chemicals may be natural or man-made. Although once used almost exclusively, pesticides are now viewed as only one component of an IPM program. In fact, chemical pesticides often are used only when it is absolutely necessary. Pesticide application must be done safely to reduce potential injury to people and the environment. The different types of pesticide are classified according to the pest(s) they control. Insecticides are used to control insects. Making body contact with the chemical, swallowing the insecticide, or inhaling it (enabling it to enter through the respiratory system) will result in insect death. Miticides are used to control mites and ticks, which are usually killed by coming in contact with the chemical. Page 7

8 Fungicides are used to control fungal diseases. Fungicides are used to prevent a plant from becoming infected with the disease. Therefore, they are applied before the disease is present. Herbicides are used to kill unwanted plants. Rodenticides kill rodents, such as rats and mice. These chemicals are usually applied as bait. Eating the chemical poisons the rodents. Nematocides kill nematodes. Nematocides are usually applied in the form of a fumigant, which is a substance that produces a smoke, vapor, or gas when applied. Molluscicides are used to kill slugs and snails. These chemicals are usually applied as bait, which attracts the slugs and snails and poisons them. Summary: Integrated pest management (IPM) is an organized program in which the best management methods available are used to keep pest populations below the economic injury level. Also, PMI is used to avoid adverse effects on humans, wildlife, and the environment. A pest is a living organism that can cause injury or loss to a plant. Pests include insects, diseases, weeds, mites, nematodes, parasites, and animals. The goal of managing pest populations is to keep losses below a level where profit is reduced. Benefits of IPM to agriculture and the environment include reduced pesticide costs, reduced application costs, less pesticide resistance, reduced contamination, fewer residues on food, and improved human health. IPM methods include biological, chemical, cultural, mechanical, and genetic control. Pesticides are the materials used to control pests. Pesticide classes include insecticides, miticides, fungicides, herbicides, rodenticides, nematocides, and molluscicides. Checking Your Knowledge: 1. What is integrated pest management? 2. What are the types of plant pests? 3. How are economics tied to integrated pest management? 4. What are some benefits to integrated pest management? 5. What methods of control are involved in integrated pest management? Page 8

9 Expanding Your Knowledge: Compile a list of cultural practices that could be employed to reduce pest problems for a crop of your choice. Possible crops include an orchard crop, a field crop, a lawn, a vegetable garden, or a greenhouse crop. Web Links: Integrated Pest Management Integrated Pest Management Integrated Pest Management Integrated Pest Management Principles Page 9