Soil Fumigation Category 2f A Study Guide for Commercial Applicators Dec. 2006 Ohio Department of Agriculture- Pesticide Regulation Certification & Training
Acknowledgements The Ohio Department of Agriculture would like to thank the following Universities, Colleges and Private Industries for their participation in the development of this manual. As we all know, study manuals are a collaboration of many entities contributing their expertise and knowledge to create a manual that is both informative and a teaching tool for those persons wishing to become commercial applicators. Again, the Ohio Department of Agriculture is grateful to those who contributed to this manual. This manual would not be possible without the participation of these persons. THANK YOU. THE OHIO STATE UNIVERSITY UNIVERSITY OF FLORIDA UNIVERSITY OF NEBRASKA UNIVERSITY OF CALIFORNIA DAVIS GREAT LAKES CORPORATION DEGESCH CORPORATION MONTANA DEPARTMENT OF AGRICULTURE NORTH DAKOTA STATE UNIVERSITY UNITED STATE GOLF COURSE ASSOCIATION LANDPRO OF JOHNSON COUNTY LLC Author: Diana Roll - ODA Editors: Stephanie Boyd - ODA William Pound - ODA Kelly Boubary - ODA Reviewed by: Michael Ellis - OSUE 2
Table of Contents Chapter 1 Laws and Regulations.6 Federal Laws.6 FIFRA...6 OSHA...6 Endangered Species Act..6 State Laws 7 The Ohio Administrative Code (The Rules)...7 The Ohio Revised Code (The Law) 7 Category Definition.7 Agriculture Pest Control.. 7 Soil Fumigation...7 The State Plan for Ohio...7 The State Lead Agency 7 The State Plan Document 8 Standards of Competency...8 General Standards....8 Specific Standards....9 Pesticide Licensing Information.9 Application Process.....9 Initial Licensing Exams.. 9 Recertification Exams....10 Commercial Renewal and Recertification Information 10 Chapter2 Soil Fumigation.. 11 Fumigation Management Plan. 11 Personal Protective Equipment. 12 Eye Protection... 12 Respiratory Protection.. 12 NIOSH Approval.. 12 Air-Purifying Equipment.. 13 Maintenance.. 13 Powered Air Protection Respirators (PAPR) 14 Air Supplying Equipment.. 14 Other Protective Equipment.. 15 Principals of Soil Fumigation... 15 Enviromental Effects on Fumigants 15 Soil Preparation for Bed or Field Fumigation 16 Types of Soil Fumigation.. 16 Raised Tarp Fumigation... 16 Broadcast Field Fumigation.. 17 Bedding Plant Soil Fumigation 20 Potting Mix Fumigation...20 Drip Irrigation Soil Fumigation...21 3
Soil Preparation for Drip Irrigation Fumigation... 21 Burrowing Pests Soil Fumigation 24 Pests with Open Burrow Systems.25 Pests with Closed Burrow Systems.. 25 Factors Affecting Soil Fumigation.. 26 Soil Temperature..26 Soil Texture..26 Organic Matter.26 Soil Type.. 26 Seals.27 Time of Application.27 Special Problems.. 27 Chapter 3 Application Principles.. 28 Soil Fumigation Applications 28 Liquefied Gas....28 Injection Applications... 28 Volatile Liquids....29 Handgun Applications..30 Shank (Chisel) Applications.30 Sweep or Blade Applications 31 Chemigation.. 31 Equipment Calibration.. 31 Chapter 4 Pests Commonly Controlled with Fumigation 33 Plant Parasitic Nematodes. 33 Root Knot Nematode 33 Stubby-root Nematode.. 34 Soil-Borne Plant Diseases.. 35 Pythium.35 Phytophthora.36 Weeds and Germination Weeds Seed Pests.. 38 Crabgrass...38 Goosegrass 38 Broad Leaf Weeds.. 39 Dandelion.. 39 Common Chickweed. 40 Henbit 40 Rodent Pests....41 The Woodchuck (Groundhog)... 41 Moles 41 Chapter 5 Soil Fumigation Equipment.. 43 Drip Irrigation. 43 4
Broadcast. 43 Shank Chisel 44 Burrowing Pest Control 45 Pellet or Tablet Type Fumigants.. 45 Gas Cartridge Type Fumigants 47 Chapter 6 Characteristics of Fumigants.. 48 Chemical and Physical Characteristics...48 Volatility.. 48 Molecular Weight 48 Boiling Point 48 Vapor Pressure Water.. 49 Specific Gravity... 49 Diffusion (Flow) Potential... 49 Water Solubility... 49 Latent Heat of Evaporation.. 49 Flammability 50 Chapter 7 Types of Fumigants 51 Product Stewardship What is it.. 51 Types of Fumigants. 51 Methyl Bromide 51 Chloropicrin.. 53 Metam Sodium.. 53 1,3-Dichloropropene. 54 Appendix A ( Example Fumigation Plan for Burrowing Pests) 55 5
CHAPTER 1 LAWS AND REGULATIONS Error! No table of contents entries found. Objectives You will learn Learn what federal and state laws govern soil fumigation Definition of category The State Plan for Ohio Standards of competency Pesticide license information Pesticide exam information Recertification information continuing education FEDERAL LAWS FIFRA This is the basic federal law administered by the Environmental Protection Agency (EPA) that regulates pesticides (their use, handling, storage, transportation, sale, disposal, etc.). The Ohio Department of Agriculture (ODA) has a cooperative agreement with the EPA to enforce some provisions of FIFRA in Ohio. Some of the provisions of FIFRA are that the EPA must register all pesticides before they can be sold or used. The pesticides must be classified as either "general use" or "restricted use. General- use pesticides are those that can be purchased without restriction. Restricted-use pesticides are those that can be used only by or under the direct supervision of a certified applicator. FIFRA also stipulates that persons who misuse pesticides (in a way that is "inconsistent with the pesticide labeling") are subject to penalties. OSHA The U.S. Department of Labor (DOL) administers OSHA. OSHA governs the record-keeping and reporting requirements of all work-related deaths, injuries, and illnesses of businesses with 10 or more workers. Endangered Species Act This act requires the U.S. EPA to ensure that endangered or threatened plant and animal species are protected from pesticides. This act requires each pesticide label to limit its use in areas where these species could be harmed. Category 6d applicators must consider the possibility that the pesticides they apply may affect endangered or threatened species. The Ohio Department of Natural Resources (ODNR) Wildlife and Fisheries Management divisions maintain the federal and state endangered or threatened species lists. Ohio applicators that want to be sure they are complying with the act must take the initiative and consult with the ODNR to be sure that there are no endangered or threatened species in their area. One of the goals of pest management is to protect off-target plants and animals from pesticides, whether they are endangered or not. 6
STATE LAWS The Ohio Administrative Code (The Rules) The Ohio Administrative code sections 901:4-11-01 to 901:5-11-08 is the regulations. These regulations give the Ohio Department of Agriculture (ODA) the authority to regulate pesticides applied, sold and used in Ohio. The rules are drafted by the pesticide and legal staff at ODA. Once the rules are completed, they are ready to be sent to the Joint Committee on Agency Rule Review (JACARR). This committee is made up of Ohio Congresspersons and senators who review the language and content of the rules. After review is completed it takes about seventy-five (75) days for the rules to become effective. The Ohio Revised Code (The Law) The law is written by the Ohio General Assembly. Subject matter is submitted to the assembly from representatives or senators. The representatives or senators introduce it into the general assembly as a Bill. The bill is heard and discussed by the regulated industry, government agencies and public. If the bill is approved, then it goes to the governor for his signature. If the bill is not approved it is back to the drawing board. When the governor signs the bill it usually takes about 90 days until the bill becomes a law. The bill is assigned to the agency best equipped to handle the law. The Ohio Revised Code section 921 is the Pesticide Law. The law regulates pesticides applied, sold and used in Ohio. The Ohio Department of Agriculture Pesticide Regulation is the entity that enforces the Pesticide Law. CATEGORY DEFINITION Category Definitions Ohio has multiple categories to meet the needs of our applicators. The category and sub-category definitions are in the regulations and backed by the law. Agriculture Pest Control Agriculture pest control category 2 means the application pesticides to all agronomic and horticultural crops, or to soils being prepared for the production of such crops, for the control of any pests other than vertebrates. Soil Fumigation Soil fumigation is a sub-category f of agriculture pest control. Soil fumigation means the application of fumigants to the soil for the control of oil inhabiting pests. THE STATE PLAN FOR OHIO The State Lead Agency The state lead agency for the plan is the Ohio Department of Agriculture. The Governor assigned the responsibility of this plan to the Division of Plant Industry on March 12, 1973. 7
The State Plan Document The plan is the document by which the Ohio Department of Agriculture, Pesticide Regulation Section and The Ohio State University Extension share the responsibilities for the certification and training of the Ohio pesticide commercial and private applicators. The Ohio Department of Agriculture is responsible for the testing and licensing of pesticide applicators. The Ohio State University Extension is responsible for the continuing education credits for those applicators that wish to re-certify and not re-test. The plan sets forth the standards by which the Ohio Department of Agriculture and The Ohio State University Extension develop study materials, pesticide exams and pesticide training. These standards are called Standards of Competency. Standards of Competency Commercial applicators are required to demonstrate their knowledge and understanding of the handling and use of pesticides by means of written, closed book examinations; based on the standards of competency set forth in 40 Federal Code of Regulations (CFR) 171.4. Standards are set forth for the Core exam and for all the categories. The additional Standards of Supervision of non-certified applicators must be met, such as availability related to the hazard of the situation. Also needed are instructions and guidance when presence of a supervisor is not required. General Standards Commercial applicators shall demonstrate practical knowledge of the principles and practices of pest control and safe use of pesticides A comprehension of labeling format and terminology together with an understanding of permitted uses, classification, associated warnings, precautions and other restrictions, such as reentry Safety factors related to handling, storage and disposal of pesticides, particularly those factors pertaining to the prevention of personal injury through accidents, misuse, symptoms of pesticide poisoning and first-aid treatment Adverse environmental effects, such as water or soil pollution and injury to non-target organisms The recognition of common types of pests, their damage symptoms, basic developmental stages and optimum periods of pesticide susceptibility Types of formulations of pesticides (both chemical and functional), their modes of action, persistence and compatibility with various other compounds Application techniques for greatest effectiveness with minimal adverse side effects Appropriate state or federal laws pertaining to the production, distribution, sale or use of pesticides and to the supervision of non-certified applicators Potential of contaminating wells, ground water and surface water by pesticides 8
Areas in the state where endangered or threatened plants and animal species are to be protected from pesticides. Specific Standards All commercial applicators, regardless of category, will be required to demonstrate a satisfactory understanding of the above general standards. In addition to this, each must further demonstrate an equally sound knowledge of a more specific nature, related to the pests, pesticide, application techniques, hazards, etc., associated with his/her respective area(s) of work. Competence in each of these specific categories and subcategories will also be determined on the basis of written examinations. (2f) Soil Fumigation: Commercial applicators shall demonstrate a practical knowledge of: types of fumigants characteristics of fumigants methods of application proper and sufficient aeration safety equipment needed for fumigation possible hazards to humans, wildlife and the environment label specific directions and recommendations product stewardship programs potential for phytotoxicity information necessary for safe and adequate application of fumigants PESTICIDE LICENSING INFORMATTION Application Process The application and fee are only valid for the licensing year noted on the application and cannot be extended to the next licensing year once it is submitted. If all requirements are not met within the license year listed on the application, the application and fee are voided and the fee is non refundable. License fees cannot be transferred from one company to another. When a first time applicant submits the application and fee, study material will be sent to assist in preparation for the examinations. Categories are listed on the application. Initial Licensing Exams Examination requirements are: the General-Core examination which covers the law, regulations, safety, disposal and related topics, and an examination for each category in which you need to be certified and licensed. The categorical examinations are specific to what area you will be applying the insecticide, herbicide, fungicide, etc. All examinations consist of multiple choice, photo identification and true/false questions. The exams are not open book exams. Exam results are mailed two-three weeks after the test date; they are not given over the phone. If you fail the exams, you must wait at least five days to retest. If you need to retest there is no additional fee required. Exams are only valid for one year from the date you pass the exam. Within that year if you do not meet the other qualifications for a license to be issued, the exams expire and you will need to retest. There is a Pesticide Applicator New School for new applicants conducted by The Ohio State University that is held every year in late February or early March. Their website is: http://pested.osu.edu. This website also offers other licensing information: test sites, recertification sites and study material. 9
Please call the Pesticide Regulation Section at (614) 728-6987 or 1-800-282-1955 to schedule your appointment to take the exams or register online at www.ohioagriculture.gov. The application is only valid for the licensing year in which you have applied. (The year is listed on the application.) If you do not meet requirements within the year that you have applied, then a new application and fee will be required, and no refund is given. Ohio Dept. of Agriculture website: www.ohioagriculture.gov - look under Pesticides. Recertification Exams Commercial applicators may also recertify by examination. Recertification exams are the same exams as the initial licensing exams. Applicators will need to take the Core exam and the category specific exams that they are licensed in and will recertify by doing this. Commercial Renewal and Recertification Information Once you have passed the applicable exams for the license and a license has been issued, you are certified for three years. The license must be renewed continuously every year in order to keep the three-year certification valid. You need to renew the license every year (at the end of September), which consists of submitting a renewal application and fee. You need to recertify every three years (the recertification due date is printed on your license) by retesting or attending recertification programs. Your recertification is based on the first year you obtained your license, which is based on the license year you passed exams and met all other requirements. Once you have been issued a license, you may begin obtaining your recertification credits at any time during the three-year recertification cycle. You must obtain the following requirements for recertification: TOTAL MINIMUM OF FIVE HOURS OF TRAINING CONSISTING OF 1 HOUR OF CORE TRAINING AND ½ HOUR IN EACH CATEGORY YOU ARE LICENSED HOWEVER, IT MUST BE A TOTAL MINIMUM OF FIVE HOURS. If you have met your category requirements you must still make sure you meet the time requirement by attending approved classes whether they are in your licensed category or not. If you do not meet the recertification requirements of 1-hour minimum in Core, at least ½ hour in your licensed category or categories with a total minimum time of 5 hours before the recertification expiration date listed on your license, then you must retest. 10
CHAPTER 2 SOIL FUMIGATION Learning Objectives You should learn: Soil Fumigation Personal Protective Equipment Used for Soil Fumigations Principles of Soil Fumigation Soil Preparation Types of Soil Fumigation How to Apply Fumigants Factors Affecting Soil Fumigation SOIL FUMIGATION Soil fumigation can yield vastly improve seedlings and crop performance. By decreasing weed competition and eliminating parasitic attack by nematodes. The fumigation cost is more than offset by increased production. Plant bed fumigation with a mixture of methyl bromide and chloropicrin has proven considerably more effective and uniform than steam sterilization or burning. When soil experts want sure-fire results, they most often use methyl bromide formulations. The composition of these fumigants can vary widely according to their specific use. The importance of soil fumigation has led to the use of automatic tarping apparatus. Tractor-mounted applicators using mechanical film layers are now widely used. When fumigating in the fall, leave the cover in place until the following spring when the soil is prepared for planting. This will help keep treated soil from becoming contaminated. FUMIGATION MANAGEMENT PLAN Some fumigant labels now require licensed applicators to be responsible for developing and following a fumigation management plan (FMP). The FMP is intended to insure safety to the applicator, site employees and surrounding areas. It is also designed to ensure a legal and effective fumigation. The FMP is meant to be the rule but is flexible enough to allow experience and expertise of the fumigator to make changes based on circumstances. Prior to writing the FMP carefully read and review both the pesticide label and the Applicators Manual for the fumigant to be used. Assemble and organize all of the information needed to develop a FMP. Preparation is the key of any successful fumigation. Once the FMP is written a copy must be given to the appropriate people. Fictional Burrowing Rodent FMP This is a fictional FMP that is to be used for informational purposes only. 11
PERSONAL PROTECTIVE EQUIPMENT Eye Protection Vision is one of our most important senses and damage from eye injuries is often permanent. Eyes are exposed to many dangers in agriculture, physical and chemical. There is a wide variety of eye protection available, ranging from safety glasses to totally protective goggles. Selection should be made according to the hazard and risk. Prescription glasses and safety glasses offer little protection when working with chemicals that can splash or spread like fumes do. Safety glasses can be enhanced with side shields which offer some protection from splash around the sides. They rarely meet label requirements for pesticide safety. Goggles offer more protection than safety glasses. They are shielded all around the lens, preventing entry of particles from any angle. Adequate protection is provided if the right type of venting is selected (Figure 2.1). Safety goggles have three types of venting: open vents for impact protection only indirect vents for chemical splash protection non-vented for protection from gases, mists and fumes. Some goggles are made wider over the bridge of the nose so they are compatible with respirators. Be sure to select approved safety goggles that also meet ANSI Z87.1-1989 standards. Figure 2.1 Types of safety goggles. Respiratory Protection Inhaling fumes from fumigants are a very common entry route of pesticides into the body. Absorption through the lungs is great and the sensitivity is high. Inhalation accounted for a high percent of the pesticide exposures, second only to dermal exposure. Inhalation exposure is one of the easiest to prevent, simply by wearing readily available adequate personal protective equipment. NIOSH Approval The National Institute for Occupational Safety and Health, under authority of the Federal Mine Safety and Health Act of 1977 and the Occupational Safety and Health Act of 1970, tests, approves, and certifies respiratory equipment as being safe for its intended purpose. Always be certain that the NIOSH compliance number is on the product before purchasing respiratory equipment. 12
Two systems of respiratory protection are available, depending on the type of respiratory risk involved: air-purification (filtering) and air-supplying. For most pesticide work, the air-purifying equipment is adequate and safe. Air-Purifying Equipment Air-purifying equipment filters pesticide particles and vapors from the air, but it does not provide oxygen where it is deficient. The pesticide can be in the form of a dust, mist, fume, or vapor. Dusts and mists are easiest to filter from the air. Fumes and vapors are more difficult and require more specific protection. Depending on the pesticide, there is a wide variety of filtering respirators available, ranging from simple dust masks to powered air protection respirators. Cartridge and Canister Respirators Figure 2.2 Cartridge type respirators. Cartridge or canister respirators are needed when pesticide vapors present a risk. Contents of the cartridge or canister absorb the vapors as the air passes through the respirator. The respirator must be equipped with an approved pre-filter to be approved for organic vapor removal. Since the air is cleaned by filtering and absorption, the respirator will not protect you when there isn't enough oxygen to maintain life. A respirator cartridge is smaller than a canister and has a shorter service life. The service life is used up when the smell or taste of the pesticide is detectible. Otherwise, replace the cartridge or canister at least every eight hours or according to label instructions. The cartridge type is typically used more often in agricultural applications. Both types are available with full-face protection, eliminating the need for goggles when eye protection is required (Figure 2.2). Maintenance Respirator cartridges have a limited service life. The service life is indicated on the package. The maximum service life can be obtained when exposure to pesticides is minimized. The cartridge continues to absorb pesticide vapors from the air, even when not being used. Store the cartridge in a zip-lock plastic bag between uses to limit the exposure. Cartridges cannot be cleaned, but they should be disposed of when their service life is used up. Respirator bodies should be washed in warm, soapy water. A clean respirator is much more inviting to wear. 13
Powered Air Protection Respirators (PAPR) Figure 2.3 A powered air protection respirator (PAPR). This type of respirator supplies filtered air to the user, the air having been filtered before delivery to the face. Air is supplied under slight pressure to the user, making breathing much easier than with a cartridge respirator, which provides air at a negative pressure. PAPR units use a small battery-powered blower to push air through a cartridge and deliver it to the facial area for breathing (Figure 2.2). They usually provide up to eight hours of use with 16 hours needed for battery charging. Powered air protection respirators have the same use/exposure limitations to air pollutants as the cartridge and canister respirators because they use similar cartridges to filter the air being breathed. Various models are available: helmet units, hood units, half-mask, full face masks, and impact resistant helmets for welding activity. Air Supplying Equipment This equipment does not filter the air to be breathed; it simply supplies it. Clean, oxygen-sufficient air is supplied from either a cylinder or an airline which brings it in from a safe source, as shown in Figure 2.4. Figure 2.4 Self contained breathing apparatus (SCBA) with a cylinder air supply (top) and with an airline that would connect to a safe air source (bottom). A self contained breathing apparatus (SCBA) is required when there is not enough oxygen present to support life (less than 19.5 per-cent oxygen) and/or when there are pollutants in the air that present an immediate danger to health and life. Examples are a manure pit with methane and hydrogen sulfide present, an uncontrolled release of anhydrous ammonia, grain fumigant in a bin, and smoke or combustion gases from a fire. 14
An SCBA consists of a full-face gas mask, an air delivery system (tubing and metering devices), and a cylinder for storage of compressed air. The safe use of an SCBA requires medical approval and training. Not just anyone can safely use an SCBA. There are few agricultural situations that require the use of an SCBA, and generally pesticide application is not one. However, if a manure pit is part of the livestock facilities, or grain fumigation is a regular part of the grain handling program on the farm, then an SCBA should be immediately available. Other Protective Equipment The product label is where you will find the information needed about what type of personal protective equipment should be worn to perform the application. Some labels require long pants, long sleeve shirts, socks, shoes and goggles be worn for the application. While others may require protective suiting, shoes, gloves and SCBA equipment for the application. READ THE PRODUCT LABEL AND WEAR THE PROTECTIVE EQUIPMENT SPECIFIED FOR THE APPLICATION to be safe PRINCIPALS OF SOIL FUMIGATION The biological, chemical, and physical aspects of soil fumigation must be understood to have a successful soil fumigation program. These factors apply to the chemical used, the pest to be controlled, and to the soil. The objective should always be to control the target pest with a minimum amount of soil fumigant. Fumigants move through soil air, dissolve in the soil water and kill in the soil water. Fumigants are volatile substances and change into gases upon injection into the soil as liquids. The vapors can only move through the continuous soil air space. They dissolve in the soil water and establish a dynamic equilibrium between the soil air and the soil water. Fumigant gas molecules then are moving back and forth from the air to the water phase as the fumigant diffuses through the soil mass. That portion of the fumigant dissolved in the soil water establishes the concentrations responsible for the kill of the soil-borne organisms. Insects which live in the soil air are killed by fumigant concentrations in the soil air. Dose equals fumigant concentration multiplied by the duration of exposure. The objective in soil fumigation is to establish a lethal concentration and maintain that concentration for a sufficient period of time to kill the target organisms throughout the soil. The ability of a fumigant to move throughout the soil profile varies with the soil type. It is harder for a fumigant to move through fine textured soils such as clays than coarse textured soils such as sand. Therefore, a clay or silty loam soil should be quite dry prior to treatment, while a very sandy soil can be quite wet. ENVIORNMENTAL AFFECTS ON FUMIGANTS Fumigants move 10,000 to 30,000 times faster in the soil air than they do in the soil water. As a soil changes from dry to field capacity, the amount of fumigant in the soil water increases and the amount in the soil air decreases. In the case of a saturated or wet soil, the fumigant will not move through the soil as a gas. Good fumigation conditions are the same as good seed germination conditions. Warm moist soil is the best. Soil temperatures between 60 F and 80 F are considered ideal. One method of checking soil is 15
to form it into a round ball and then drop it to the ground or press into it with your finger. If the soil breaks apart easily, it is suitable for fumigation. If it stays together, it is too wet to treat. A change in soil temperature also changes the solubility of the soil fumigants in air and water. More fumigant is dissolved in the soil water at 40 F than at 80 F; the solubility of fumigants in the water increases at the lower temperatures. At the same time, the percent of the fumigant in the soil air decreases. The decrease in the amount of fumigant in the soil air because of the cold soil results in slower movement of the fumigant s compared with warm soil. As the soil becomes more and more compacted, the particles make physical contact, and the water films bridge over resulting in an impermeable condition. Thus, compacted soil layers cannot be effectively penetrated with fumigants. However, this same principle can be utilized to hold fumigants in the soil by compaction of soil particles near the surface, providing a type of seal by closing off the soil air spaces. After the fumigant is injected into the soil, it vaporizes and a portion of it moves upward. As it approaches the soil surface, it tends to move more rapidly, because of the drier conditions and increased porosity. If the surface is sealed by compaction or with some type of sealing device, loss through the surface will be reduced. A clod represents two problems in control. A compacted soil clod will not allow the fumigant to penetrate and control the organisms within the clod, and the soil surface is very difficult to seal if there are large clods on the surface. Organic matter in the soil also affects the mobility of the fumigant in the soil. Soil fumigants are readily absorbed by organic matter. Also, undecayed plant remains can foul application equipment and puncture plastic film. If possible, organic matter should be allowed to decay before application. Fumigant rates should be increased where soils contain large amounts of organic matter. Weed control is greatly influenced by soil conditions. Soil too wet, too dry or cloddy will reduce the control received. These same conditions also reduce the effect of methyl bromide-chloropicrin on diseases. SOIL PREPARTATION FOR BED OR FIELD FUMIGATION Plow, rip or otherwise till the soil to the depth to which effective treatment is required. The soil should be worked until free of clods or large lumps. Residue from previous crops should be worked into the soil to allow for decomposition prior to fumigation. Soil moisture should be adequate for seed germination. Coarse textured soils can be fumigated with higher moisture content than fine textured soils. For best results, soil should be kept moist for at least four days prior to treatment. Do not fumigate if the soil temperature is below 50 F. For best results, fumigate when soil temperature is 60 F to 80 F at the depth of 6 inches. TYPES OF SOIL FUMIGATION Raised Tarp Fumigation (Bromo-O-Gas, Bromo-O-Gas 2% and Terr-O-Gas 98 are registered for this use.) 16
Raised Tarp Fumigation Method for Plant Beds and other Small Areas This method of application can be used for seed and transplant beds, nursery and greenhouse soils, potting soil mix and golf course greens. Figure 2.5 Small bed fumigation The purpose of raising the tarp, through the use of such items as listed below, is to create a dome underneath the plastic tarp to allow movement of methyl bromide throughout the area to be fumigated. This movement allows for even distribution of the gas and hereby uniform control of the pest, disease or weed problem. Support the center of the cover to provide a small gas dome. Inflated plastic bags, crumpled fertilizer bags, burlap bags stuffed lightly with hay or straw, inverted baskets, flowerpots or bottles placed on the soil may be used for support. To avoid puncturing of the cover, items with sharp edges should not be used. Evaporating containers are essential for the volatilization and uniform dispersion of fumigant. Shallow pans or basins made of plastic or metal, except aluminum, magnesium, or zinc are satisfactory for this purpose. One procedure is to place the cans in undercover trays spaced evenly over the area to be treated. The cans are placed so that they are resting lightly on the points of the spikes in the tray. After the cover is in place and sealed around the edge, push down on the cans, opening them to release the gas. These openers eliminate the need for evaporator pans and tubing, and also allow the tarp to be between the applicator and the tray. Leave the cover in place for at least 24 hours. Aerate the soil after removing the cover at least 72 hours prior to planting. In cool weather, allow the cans to remain unopened under the cover for two to three hours to take advantage of the sun s heat which can speed up the dispersion of fumigant under the cover for better results. If the cans are cold, placing them in a bucket of warm water for a few minutes before placing them under the cover will improve dispersion. After cans have been completely emptied, and aerated, dispose of them according to the label or by other procedures approved by state and local authorities. Fumigant cans that are considered empty often contain vapors and should be kept in a well-ventilated location for 12 hours before disposal. Dosage is 0.4-2.0 pounds per 100 square feet for an exposure period of 24 hours when soil temperature is 60 F or higher. The gas penetrates the soil to the depth it has been worked. When soil temperature is between 50 and 60 F, extend the exposure period to 48 hours. Do not treat when soil temperature is below 50 F. Only correctly trained and equipped handlers who are performing a handling task permitted by labeling can be in the treated area from the start of the 17
application until after the tarps have been removed. Read the label under Directions for Use for additional precautions and rates to be used. Broadcast Field Fumigation Larger areas can be treated with methyl bromide using tarp-laying fumigation rigs. These rigs inject the chemical several inches deep through chisels spaced approximately 12 inches apart. The equipment lays a sheet of polyethylene film (tarp) at the time of application. Strip-treatment rigs cover half the field in alternating strips, with polyethylene film. This rig automatically lays the film down and covers the edges with soil to seal in the fumigant. Two or three days later these strips of tarp are removed and the alternate, untreated strips are treated in the same way. Another type of rig glues the edges of the film together in a manner which allows treatment of the field in one continuous operation. 1. Application Equipment Several distributors of soil fumigants also supply application equipment ( rigs ). When purchasing a fumigation rig, pay close attention to details of construction. Brass or stainless steel fittings should be used throughout, and all tubing should be Teflon or Teflon-lined steel braid. Galvanized pipe should not be used. All rigs should include a filter to remove any particulates from the fumigant, and a check valve to prevent backflow of the fumigant into the pressurizing cylinder. Most rigs also include a flow meter or a constant pressure system with orifice plates to insure the proper amount of fumigant is applied. Make sure the pressure rating of all components of the rig is at least 500 psi. An experienced dealer representative should fully explain the operation, calibration, and maintenance of the rig. Before first using the rig, make sure all components (filters, flow meters, etc.) are installed so that flow is in the direction indicated. Applicators should be aware of the potential for contamination of nitrogen gas cylinders used as a propellant for fumigants. Cylinders containing nitrogen gas may later be refilled and reused for medical and industrial purposes. If these cylinders are contaminated during agricultural use, serious risks to the next user from pesticide exposure could result. To prevent the backflow of fumigant into a compressed gas cylinder, applicators must: Make sure that positive pressure is maintained in the nitrogen cylinder at not less than 200 psi during the entire time it is connected to the fumigation rig. Ensure that rigs are equipped with properly functioning check valves between the nitrogen cylinder and fumigant cylinder. The check valve is best placed on the outlet side of the nitrogen pressure regulator, and is oriented to only allow nitrogen to flow out of the cylinder. Always pressurize the system with nitrogen before opening the fumigant cylinder valve. FUMIGATION GUIDE WARNING!! A FACE SHIELD AND SAFETY GLASSES MUST ALWAYS BE WORN WHEN PERFORMING MAINTENANCE, TESTING, OR CONNECTING CYLINDERS. Before using a fumigation rig for the first time, or when preparing it for use after storage, the operator should check the following items carefully: Check the filter, and clean or replace the filter element as required. 18
Check all tubes and chisels to make sure they are free of debris and obstructions. Check and clean the orifice plates. Pressurize the system with nitrogen, and check all fittings, valves, and connections for leaks using soap solution. Install the fumigant cylinder, and connect and secure all tubing. Slowly open the nitrogen valve, and increase the pressure to the desired level. Slowly open the fumigant cylinder valve, always watching for leaks. When the application is complete, close the fumigant cylinder valve and blow the residual fumigant out of the cylinder with nitrogen. At the end of the season, disconnect the fumigant cylinder, and seal all tubing openings with tape to prevent the entry of insects and dirt. Store the application rig in a protected, secure area away from children. 2. Overall Application Inject this product with a chisel type applicator having the chisels spaced no more than 12 inches apart and injecting the fumigant to a depth of 6-8 inches below the soil surface. Normally, film that is used in solid tarp fumigations (entire field covered) is 0.001 inch (1 mil) thick. Film that is 1.25 mils thick is used on strips or raised beds. When treatment areas are done by hand, 2.0 mil thick film is used. Although the cost is higher, a high vapor barrier film is available to reduce the loss of methyl bromide to the atmosphere. The soil surface must be covered with polyethylene film immediately after treatment with simultaneous film laying equipment, or sealed with a roller or culti-packer and covered within 20 minutes with polyethylene film or other suitable cover. Consult dosage rate table for proper rates of application and exposure periods. At the end of exposure period, remove tarpaulins and aerate for 3 days before seeding and 5 to 7 days before introducing transplants or vegetative plant parts. 3. Row or Bed Application. Apply the broadcast rate to the area actually treated, i.e., the area delimited by the film mulch. Consult dosage rate table for treatment rates. Use one or more shanks per bed, spaced not more than 12 inches apart, depending on the area to be treated. Inject the fumigant 6-8 inches below the surface of the bed and simultaneously cover with polyethylene film or other suitable cover. At the end of the exposure period, remove tarpaulins and aerate for 3 days before seeding and 5 to 7 days before introducing transplant or vegetative plant parts. Where polyethylene film is to be utilized as mulch, aeration is accomplished by making holes in the film on spacing appropriate for the crop to be planted. Keep pets, livestock, and other domestic animals out of the treated area during application, during the exposure period as specified for applications in Directions for Use and during removal of the tarpaulin, if used. 19
Figure 2.6 Large area fumigation Bedding Plant Soil Fumigation Many greenhouse growers and nursery growers have been turning to the fumigation of potting soil mixes as an energy efficient method for good soil sanitation. (Figure 2.7) Soil Fumigation Read and follow all the label instructions before performing any soil fumigations. The label and applicators manual have all the information needed to do proper soil fumigation. Potting Mix Fumigation Potting mixes including decomposed compost, soil mixes, and manure can be fumigated to control some weeds, plant-parasitic nematodes, insects, and some soil-borne diseases. Fumigation should take place outdoors or in a well ventilated area away from desirable plants or occupied buildings. The material to be treated should have a temperature of 60 F or above, be loose, and moist enough for good seed germination. To ensure a good seal, pile the material to a depth of 18 inches on a concrete surface or on wet ground. Piles 2 to 3 feet high can also be treated provided perforations are made in the pile surface at one foot intervals to assist penetration. Once the pile has been made, install supports to hold the cover a few inches above the pile surface to aid in proper fumigant diffusion. Evaporating pans are essential for the volatilization and uniform dispersion of fumigant except where a vaporizer is used. Shallow pans or basins made of plastic or metal (except aluminum) are satisfactory for this purpose. For delivery of the product from outside the tarpaulin, polyethylene tubing is required. Anchor one end of each tube into an evaporating pan with tape or a suitable weight. This ensures that the liquid will be directed into the evaporating pan. Place evaporating pan(s) with anchored applicator tubing about 30 feet apart on the pile surface. Extend the free ends of the polyethylene tubes outside the area to be covered. Cover with a polyethylene sheeting or other gas confining material of 4 mil or greater thickness. Seal the edges by burying, covering with moist sand or soil or by means of sand snakes. Attach applicator tube to the can 20
opener or cylinder valve outlet and release fumigant. Use a cylinder dispenser or scale to meter small amounts from cylinders. Special units are available for use of 1.5 pound cans that combine opener and evaporating pan functions, and are designed to be used with all parts under the tarpaulin. Consult the label for proper rates of application and exposure periods. At the end of the exposure period, unseal opposite ends of the tarpaulin and allow aerating for at least 30 minutes before completely removing the tarp. To avoid phytotoxicity, aerate for 24-72 hours before planting. Potting mixes in flats may also be treated. Arrange the flats in loose criss-cross stacks no more than 5 feet high, then cover and seal as described above. Introduce the fumigant at the top and in the center of the stack. Use one injection point for each 100 cubic feet. Drip Irrigation Soil Fumigation Drip irrigation fumigation with an application of chloropicrin mixed with 1,3-dichlororopropene followed by metam sodium. It can also be chloropicrin alone followed by metam sodium these are the most effective registered chemical alternatives to methyl bromide chloropicrin fumigation in strawberry for the control of pathogens, nematodes, and weed seeds. Because chloropicrin and 1,3-dichloropropene are less volatile than methyl bromide, they can be applied to raised beds through drip irrigation systems. These active ingredients have been shown to be as effective in controlling soil borne pathogens and most weed seeds, resulting in comparable strawberry yields. Drip irrigation fumigation is desirable because workers are not required to be in the field during application. However, successful drip fumigation requires adequate soil preparation. Also well-designed drip irrigation system, dependable chemigation equipment, and timeliness of the process to accommodate longer plant-back time. Soil Preparation for Drip Irrigation Fumigation As with all soil fumigation, the first step is to properly prepare and till the soil. Current soil preparation and bed listing practices used after methyl bromide fumigation are generally adequate. Following this, firmly pack the beds and eliminate any dirt clods. If the soil is dry, it may be necessary to pre-irrigate with enough water to initiate weed seed germination. Uniform water distribution is necessary in a drip irrigation system and is easiest to obtain on fairly level terrain. On steep or hilly grounds, create beds that follow soil contour lines at grades that do not exceed 4 ft. uphill or 8 ft. downhill from the beginning of the drip line. When laying the plastic tarp, remove any shanks or chisels to avoid creating channels in the soil, which can result in poor water and fumigant distribution in the soil bed. Repair any holes or tears in the plastic tarp. Avoid embossed tarps to reduce loss of fumigants through volatilization. The use of virtually impermeable film (VIF) will enhance weed control in the bed. However, VIF holds fumigants in the soil for longer periods than the standard tarp and longer plant-back time or bed ventilation for 2 weeks before planting may be required (refer to the pesticide label). Amount of Water If chloropicrin or 1,3-dichlororopropene is applied simultaneously with metam sodium, they react and rapidly degrade in the irrigation water. Instead, they should be applied sequentially with the first application consisting of 1,3-dichloropropene plus chloropicrin or chloropicrin alone followed 5 to 7 days later with an application of metam sodium. Applying the materials in this order helps to maximize their effectiveness because 1,3-dichloropropene and chloropicrin are most effective in drier soils whereas metam works best in moist soils. 21
1, 3-Dichloropropene and/or Chloropicrin. It is important to use the appropriate amount of water so that the fumigant is evenly distributed throughout the target soil treatment zone. Table 1 lists the recommended amount of water needed to fumigate various soil types to 2 feet of soil depth. For example, in a sandy loam soil 2 inches of water in the soil bed is recommended to fumigate down to 24 inches. With two drip tapes, this provides a 40-inch lateral spread as well (10 inches on each side of a tape). If irrigation time is limited, cutting back to 1.75 inches on sandy loam soils is often acceptable because fumigants move 3 to 5 inches beyond the wetting front and control should extend down to the 2-foot depth. Although the fumigant will volatilize and move beyond the wetted zone, the best treatment appears to occur within the wetted area. If the irrigation amount is cut back to the minimum recommendation of 1.5 inches for sandy loam soils, the soil profile will be wetted down to 18 inches with 6 to 8 inches horizontal spread on both sides of each drip tape. Table 1. Estimated water amount needed to treat two feet of soil depth using two drip tapes when applying 1, 3-dichloropropene and/or chloropicrin. 1 Application time using 2 tapes (hours) Soil type Fine sand and loamy fine sand Sandy loam and fine sandy loam Sandy clay loam and loam Clay, clay loam, and silty clay loam Drip tape flow rate Amount of application water (gpm/100ft) Inches per acre (gallons)2 0.20 0.34 0.50 0.67 Comments 1.6 (27,000) 13.9 8.2 5.5 4.1 Pre-irrigation with one inch of water is needed 2.0 ( 34,000) 17.3 10.2 6.9 5.2 Minimum of 1.5 inches is recommended 2.6 (44,000) 22.5 13.4 9.0 NR Split application may be required 3.2 (54,000) 27.7 16.3 11.1 NR Soils not common in strawberry production 1 Application time and water volume based on 40-inch average bed width (64 inches center-to-center). 2 One broadcast acre-inch of water is about 27,000 gallons. One acre-inch of water for a 40-inch wide bed is about 17,000 gallons. NR = not recommended Drip irrigation fumigation with recommended amounts of irrigation water will provide good fumigant distribution in soil. This will reduce fumigant volatilization losses by increasing the amount of fumigant in the water phase and decreasing the total air space available for fumigant diffusion in soil. If not enough water is used (less than 1.5 inches), the fumigant will be poorly distributed and more likely to volatize, resulting in less effective control and lower strawberry yields. In addition, with insufficient water and without an emulsifier, fumigants such as 1,3-D or chloropicrin may separate in the irrigation pipelines if the concentrations exceed their solubility limits of 2,000 parts per million (ppm). Using too much water may lower the fumigant concentration in the main line below 500 ppm, which may also reduce the fumigant effectiveness. Also, beds can become unstable and collapse with excessive water application amounts. Bed stability may limit the volume or application rate of water that can be applied. 22
Metam sodium and metam potassium are water soluble and generate the active ingredient methyl isothiocyanate (MITC) after being applied to the soil. A minimum of one inch of water is recommended for the sequential application of metam to most soil types. Drip Tape Flow Rate and Spacing In drip fumigation, the rate of water flow and the spacing of drip tapes are critical to the even distribution of the fumigant throughout the field as well as in the soil treatment zone. While a water distribution uniformity of 90% is possible in a well designed and operated drip system, at least 80% is necessary for acceptable fumigation. (Table 1). Low-flow drip tape requires longer application time that may become inconvenient. Avoid high-flow drip tape (greater than 0.7 gpm/100 ft) if it causes any wetting of the furrows or run off, or if it causes the beds to collapse. High-flow tape is not recommended except for soils with high water permeability. To achieve adequate water distribution uniformity, the pressure in the drip tape throughout the field should not vary more than 3 psi (i.e., from 6 to 9 psi). In addition, the system must be free of leaks and clogged emitters and be flushed and pressure tested before fumigation. It is imperative to use good quality irrigation components and drip tape. Leaks cause fumigant loss and possibly odor and emissions problems. It may be necessary to reconfigure drip tape in order to obtain good water coverage across the soil bed. Most strawberry beds of (sandy loam soils), can be covered by one drip tape up to 10 inches on each side. Therefore, two drip tapes are recommended for drip fumigation of most strawberry beds. In the two-row strawberry beds (narrow beds with two tapes near the center); spread the tapes as far apart as possible so that the edge of the bed is covered. In the four-row strawberry beds (wide beds with two tapes close to the shoulder), move the tapes a few inches towards the center to treat the middle of the bed. A third drip tape in the center may be needed if the bed top is wider than 40 inches. A third drip tape is also recommended in wide beds on sandy and loamy sand soils where limited lateral water movement may limit fumigant distribution. Determining the Fumigant Concentration in Irrigation Water Fumigant concentration in the main line may vary from 500 to 1600 ppm, depending on the soil, fumigant type, and water application rate. Below 500 ppm, the efficacy of chloropicrin and 1, 3-dichlororopropene to control soil-borne pathogens may become insufficient. Also, because the solubility of chloropicrin and 1, 3-D in water is less than 2000 ppm at 20oC, exceeding 1500 ppm may result in precipitation of these fumigants in the irrigation pipelines. Fumigant concentration in water can be calculated as follows: Chloropicrin: ppm chloropicrin = 119,826 x (# pounds chloropicrin/# gallons water) Inline: ppm (chloropicrin + 1,3-D) = 87,872 x (# pounds /# gallons water) Table 2 shows chloropicrin concentrations as a function of application rate and water volume. A similar table can be prepared for 1,3-dichlororopropene/chloropicrin (one gallon weighs 11.2 lb or 6.57 lb 1,3-D and 3.73 lb chloropicrin) but is not provided here because 1,3-dichloropropene requires a special permit to apply. Table 2. Chloropicrin concentration (ppm)1 during drip application. 23
Chloropicrin concentration (ppm)1 during drip application. Other Important Calculations Needed for Drip Fumigation Determine the actual treated (bed) area, the total volume of water, and the weight of fumigants to be applied. Strawberry beds usually occupy 50-70% of the total area in the acre. Because only the beds are treated, this calculation can be important in determining how much fumigant is necessary for the treatment. Calculate the time required for application based on the flow rate of the drip tape Burrowing Pests Soil Fumigation There are a few common burrowing vertebrate pests in Ohio. Sometimes they can cause a great deal of damage to crops, landscapes and lawn areas. Some make their burrows or homes in the soil but do not inhabit it continually. Others make their homes and inhabit the soil continually. These pests can have an 24
elaborate network of tunnels and dens underground. Depending on the numbers of pests and the amount of tunneling, this can weaken soils and cause structural problems. The fumigant may be applied to underground burrow systems located in non-cropland areas, crop areas, or orchards occupied by burrowing pests. All treatments for control of the pests in burrows must be made outdoors. The product must be applied directly to the underground burrow systems. Before using any fumigant for burrowing pests control read the product label restrictions under Environmental Hazards, Endangered Special Local Restrictions. The product may be used our-of doors only for control of burrowing pests. Document any burrows that open under or into occupied buildings, and do not apply to these burrows. In addition, check for any other source through which the gas may enter into occupied building as a result of application to burrows. I f there is any way gas can move through pipes conduits, etc. from burrows, do not treat these burrows. Prior to treating a rodent burrow on a property containing an inhabited structure, the applicant must provide the customer (e.g. tenant, homeowner, or property manger) with a MSDS or appropriate sections of the Applicators Manual. Pests with Open Burrow Systems Locate all entrances to each burrow in the system. Treatment of more that one entrance in a system is often desirable as systems often overlap and are not defined. Treat all entrances except for those entrances you are sure that connect to already treated entrances. Insert product into each entrance to be treated. Pack each treated entrance with crumpled paper and shovel soil to completely cover the paper. Using crumpled paper will prevent soil from covering the product and slowing down its action. Rocks, clods of soil, cardboard, etc. may by used for this purpose. Be sure to seal ALL UNTREATED entrances by shoveling and packing soil and or sod to completely seal the opening. Inspect treated areas 1 or 2 days following treatment for signs residual activity of target species. Treat all reopened burrows in the same manner prescribed. (Fig 2.8) Woodchuck (Groundhog) Pests with Closed Burrow Systems For species with closed burrow systems locate the main underground runway. This is done by probing with a smooth-sided rod 12 5o 18 inches from the fresh mound. For A sudden reduction in soil a resistance to the probe indicates that the main runway has been located. Once the main runway is located, remove the probe and apply the product through the probe hole. Do not treat if soil is extremely dry or if there are no signs of pest activity. Make a tight seal to close probe hole by using a clod of soil or a sod 25
plug to cover the hole. You may also use the heel of your shoe to push sod or soil over the surface opening. If the probe hole is more than 1 inch in diameter, place crumpled paper in the hole before closing it with soil or sod. After treatment you may check area for residual pest activity by poking holes in main runways of burrow systems flagging holes and inspecting them later. You should all new runways on both sides of plug. (Fig 2.8) Mole FACTORS AFFECTING SOIL FUMIGATION There are a number of factors that can affect the efficacy of fumigants and how they control pests. We have listed some common factors below with a brief description. Soil Temperature Most fumigants work best when temperatures are between 60 and 80 degrees F at 6 inches depth. When soil temperatures are lower, chemicals volatilize more slowly and sufficient concentrations of fumigant may not be reached. At lower soil temperatures, phytotoxic concentrations of fumigant can be retained in the soil for long periods, and delay planting. If temperatures are above 80 degrees F, the gas may leave the soil too rapidly to give effective control. Soil Texture Soil should be in good condition. Large clods will allow the gas to leave the soil too quickly to do an effective job of control. Disease-causing organisms inside clods are especially difficult to control because they are protected from the fumigant. Soil should be worked to the desired depth of treatment, usually plow depth. Soil should be worked to good seed bed condition at the time of fumigation. Organic Matter Be sure all plant material is well decomposed. Under composed plant material is not easily penetrated by fumigants and pathogenic organisms within such material will not be controlled. Under composed crop residue can form chimneys through which fumigants escape to the soil surface. Soil Type Soil type influences the amount of fumigant used. Because of absorption of chemical by organic matter, muck soils generally require twice the amount of fumigant that would be used on the mineral soil. Heavy soils require more fumigant than light soils. Heavy clay soil cannot be effectively fumigated. Again, follow product label instruction regarding dosage and soil type. 26
Seals Fumigants should be sealed into the soil to ensure that a lethal concentration and exposure time is reached. The type of seal used varies with the volatility of the fumigant. High volatility fumigants must be sealed with a gas proof cover. This is usually a plastic tarp sealed at the sides and ends with soil. Lower volatility chemicals can be sealed with water or by packing the soil with rollers or drags. Water seals are generally accomplished by a light watering sufficient to wet the top ¼ inch of soil. Time of Application Fumigants are applied best in late summer of early fall. Soil temperature and moisture are generally favorable for fumigation. A fall application after crop removal allows the chemical to dissipate over the winter. This will allow spring plantings to take place at the normal time. Spring fumigation is often delayed by cool, wet soils. As a result, planting can seriously delayed by the post-fumigation waiting period required. Special Problems Fumigants reduce population of non-pathogenic as was as pathogenic organisms. This can create special problems for growers. Fumigants can temporarily reduce populations of nitrifying bacterial increasing ammonium levels that can damage early planted crops such as celery and lettuce. This problem is most common on high organic soils. Fumigation should be avoided during late fall and early spring especially on these soils, so that bacteria populations recover before planting. Ammonium type nitrogen should not be applied at planting under these conditions. 27
Chapter 3 Application Principles Learning Objectives You should learn: Different types of application equipment How to use the equipment SOIL FUMIGATION APPLICATIONS Application Techniques and Equipment Various types of soil fumigant application equipment are commercially available. Appropriate soil incorporation equipment and soil sealing equipment should follow or be attached to the fumigant equipment. Good fumigation equipment is expensive to build and maintain. Sometimes it is necessary to buy custom designed and built equipment for specific purposes. Because fumigants are highly corrosive, equipment manufacturers must construct equipment from materials tolerant or resistant to these chemicals. Many fumigators either rent fumigation equipment or lease it from their fumigant supplier. Proper care of fumigation equipment is essential. Clean application equipment immediately after use, and cover or coat all parts with a lightweight fuel oil before storing. Liquefied Gas Above Ground Applications. Several devices are commercially available for applying liquefied gases to small areas, such as greenhouse growing media and nursery soil. Cover soil to be treated with plastic. Release fumigant through a plastic tube to an evaporation pan placed under sealed plastic. Fig 3.1 Aboveground application onto an evaporation pant under a tarp The fumigant flows under pressure from the container to the soil to be fumigated. Large cylinders require valves and pressure regulators to control the delivery of the gas to the evaporation pan. Use a separate pressurized cylinder of nitrogen to maintain a constant pressure to the fumigant cylinder, ensuring a uniform application rate. Equipment used with pressurized cylinders can be complex. The applicator must be certain that the application systems are designed to deliver and withstand the pressurized fumigant. Injection Applications, For overall field application (broadcast) of liquefied gases, apply the fumigant using a tractor with sufficient horsepower to pull shanks (chisels) through the soil at the required depth 28
and speed. For shallow applications (6" to 12"), mount shanks 12 inches apart on a tool bar connected directly to a machine that lays a plastic tarp. For deep applications (18" to 30"), mount shanks up to 66 inches apart, depending upon fumigation conditions. Fumigant delivery rates depend on equipment speed and flow rate of the chemical. The most commonly used machine to seal the soil with a plastic tarp consists of two discs that open small furrows immediately outside the area to be treated. These discs connect to a device that unrolls polyethylene plastic over the treated area. Small press wheels insert the plastic into the open furrows. Closing discs seal the plastic by throwing soil back into the furrow. 3.2 Broadcast application To treat a field on a broadcast basis, apply one strip as described above, then remove and replace one set of discs with an adhesive dispenser. Seal one side of the second plastic sheet using the adhesive to the first plastic sheet, and seal the other side of the second plastic sheet in the furrow made by the remaining discs. Repeat to fumigate and cover the entire field with plastic. The same type of fumigating equipment also is suitable for band applications (strip or row applications). For deep (18" to 30") injections, sealing with a plastic tarp may not be necessary, depending on the target pests. Volatile Liquids examples: 1,3 dichloropropene, or metam sodium Trench Applications. To treat very small areas, such as ornamental planting beds, place the prescribed dosage of liquid fumigant in a small container. Pour the liquid into the bottom of a furrow 6 to 8 inches deep. Cover and seal trench. Form a water seal using a small amount of water. 29
Fig 3.3 Trench Type Application Handgun Applications, To treat small areas, such as experimental plots and nursery beds, use equipment with a holding tank connected to a hollow pointed base for penetrating the soil. A plunger device or drip device releases a known quantity of fumigant for each penetration. 3.4 Hand-heal Ground Injector Shank (Chisel) Applications This method is the one most commonly used to treat large-scale areas, such as agricultural crops. Make field applications using tractors with sufficient horsepower to pull the shanks through the soil at the required depth and speed. Narrow knifelike shanks (such as forward-swept shanks) inject fumigant. Metal delivery tubes attach to the trailing edges of the shanks. Delivery tubes release the fumigant in the bottom of the furrow made when pulling the shank thorough the soil. For broadcast applications, shank spacing usually equals the depth of injection. Maintain constant pressure to the metering pump, such as electrical or hydraulic pumps, power takeoff system (PTO), or ground-wheel drive. Regulate delivery rate using various combinations of pressure, nozzle orifice, shank spacing, and speed of travel, depending on the pressure system serving the metering pump. Shank equipment works for broadcast or band applications. For row applications, use equipment with either one or two shanks to treat only the soil where the crop will be planted. Seal the application with a plastic tarp or by mechanical compacting of the soil. If injection shank traces are present, disc soil to remove traces prior to sealing the soil. 30
Fig 3.5 Basic Schematic of a Shank Applicator Illustration Sweep or Blade Applications Attach fan shaped sweeps or blades equipped with evenly spaced fumigant outlets to the shanks and draw them through the soil. Seal the application with a plastic tarp or by mechanical compacting of the soil. If blade shank traces are present, disc soil to remove traces prior to sealing the soil. Drench Application. Add the fumigant to water and drench the soil with this solution. This method is useful in nurseries, ornamental plantings, and orchards. Chemigation. To fumigate soil by chemigation, meter and inject a liquid fumigant into irrigation water. Fumigant chemigation is applied through several types of irrigation systems, most commonly center pivots. Equipment includes an injection pump and nurse tank system. Proper setup includes check valves between the injection pump and both the fumigant supply and the water source. Keep all screens and filters clean. Use as large a droplet as possible to avoid loss of fumigant through volatilization in the air. Chemigation often requires pre-irrigation to bring the field to the desired moisture level prior to fumigation. Moisture levels must be even throughout the field. Chemigation requires a high degree of attention to detail, an understanding of the equipment used, and constant monitoring during the application. (For more information on chemigation, see Using Chemigation Safely and Effectively. Volatile Solids example: dazomet Broadcast Applications. Apply granules evenly over the soil and incorporate them, or inject the granules into the soil. For small scale applications, use a shaker and apply over the area. Incorporate granules into the soil and seal. For large-scale applications, use a granule spreader to broadcast treat and then incorporate, or use a fertilizer drill or granule distributor that will deliver the granules at the desired 31
depth. Adjust application rate by changing the size of the opening from the hopper or by altering the speed of travel. Incorporate the granules into soil to the proper depth, immediately after spreading them, using a rotary hoe or disc seal soil with a mechanical compactor. Equipment Calibration Calibrate all applicators to deliver the desired rate of chemical. All commercially constructed applicators are designed to alter fumigant rates. Applicators use two basic methods for application equipment calibration. The first method measures the amount of material applied over a known area. The second method collects a volume of fumigant for a specific time period and the measures the distance covered in the same time interval for a volume to area ratio. 32
Chapter 4 Pests Commonly Controlled with Fumigation Learning Objectives You should learn: The nematode pests in soil The disease pests in soil The rodent pests in soil Weed pests The controls of soil pests PLANT PARASITIC NEMATODES There are a number of plant parasitic nematodes that inhabit the soil and cause damage to plants. These are controlled by soil fumigation. A few common ones are as follows: Root Knot Nematode Root knot first attracted attention in 1855 when it was found in a greenhouse in England. Since then it has been a cause for concern over much of the world. It affects more than 2,000 species of plants including economically important forage crops, small grains, fruits, vegetables, field crops, nursery crops, and turf grasses. Root knot nematodes are cosmopolitan in distribution and occur widely in the United States. Fig 4.1 Root Knot Nematode Symptoms Root knot is very distinctive because of the galls or swellings produced on roots and underground portions of stems. These deformations can often completely ruin crops for sale. Plants, if infected when young, will be stunted, more susceptible to drought stress, and show symptoms of nutrient deficiency. Large and small roots may be affected with swellings varying from round sphere-like galls to elongated spindles formed from large numbers of individual galls growing together. Root knot galls involve the entire root in the affected zone. They do not take the form of easily detached galls like those produced by nitrogen-fixing bacteria on the roots of legumes. Root knot galls should not be confused with the fungal disease, club root, on cruciferous crops. In most instances, root knot is characterized by smaller swellings, and more uniformly distributed infection on the lateral feeding roots than is typically seen with club-root. When the galls formed by the root knot nematode are broken open, shiny white bodies about the size of a 33
pinhead, the enlarged female nematodes, are usually found. Also, glistening white to yellow egg masses are present on the root surface. The galls formed by club-root do not possess this characteristic and are usually pinkish or brick colored. Phenoxy-type herbicides such as 2,4 D can cause swellings on stems of cruciferous crops which superficially look like root knot galls. Herbicide damage on these crops will not affect the roots, however. On young potato tubers the outer surface appears rough and warty because of the enlarged females underneath the skin. Causal Organism Root knot is caused by a small round worm, Meloidogyne spp. There are about 40 species at the present time. Not all plants are susceptible to any one species. Fig 4.2 Root Knot on Tomato Juveniles emerging from eggs in the soil penetrate between and through cells to a position at the center of the root usually near the growing tip. Feeding by the nematodes causes increases in root cell numbers and size. Enlarged cells, called giant cells, serve as food sources for female root knot nematodes. During feeding, juveniles which will become females undergo a series of molts and enlarge. The female does not move from the feeding site. Each female deposits 300-500 eggs in a protective, jelly-like matrix at the root surface. Eggs, particularly in the egg mass, can withstand unfavorable environmental conditions. They represent one means of overwintering. Root knot nematodes may also overwinter in the soil in a juvenile stage. Root knot nematodes are often introduced into a growing area in infected planting stock. Stubby-root Nematodes Stubby-root nematodes, Paratrichodorus (or Trichodorus) spp. are in soils. Stubby-root is the most damaging nematode of corn because corn is highly susceptible and these nematodes are so widely distributed in coastal plains soils where much of the corn is grown. These nematodes feed mostly at root tips, thereby stopping root growth. As new root growth continues to be stopped by feeding of stubby-root nematodes, the root system takes on a characteristic "stubby-root" appearance. Affected root tips may be "stubbed" without discoloration or a slight discoloration may be evident. With some plants, usually not of the grass family, the main effect produced is a reduction of root system with no obvious "stubbing." These injured plants exhibit a small root system with fewer and shorter secondary roots than would have otherwise been present. Above-ground symptoms are the typical 34
symptoms of nematode damage: stunting, yellowing, and slow growth. Plants are rarely killed by stubbyroot nematodes. Fig 4.3 Stubby-root Nematode damage of Corn The stubby-root nematode life cycle is simple, going from egg through four molts to adult without changes in body form except that adults are larger than larvae. The life cycle is relatively short, reportedly ranging from 16 to 17 days at 86 F and from 20 to 22 days at 71.6 F. Populations may increase tenfold in 60 days. The population thus builds up rapidly even in the cooler spring months, making it a serious problem on early-planted, susceptible crops such as corn. The population density may also decline very rapidly. This can make diagnosis rather difficult since peak populations may be missed. It is fairly common that a soil sample for nematode analysis is not taken until after the stubby-root population has declined to low levels. When this happens, the diagnosis is based on the root-system symptoms. For this reason, a root system with symptoms should be sent with the soil sample if stubby-root nematodes are suspected. While stubby-root nematodes have a fairly wide host range, corn and other members of the grass family are the most susceptible hosts. Other plants rated as good hosts include soybeans, cotton, sunflowers, and many vegetable crops. Poor hosts include tobacco and rye. The wide host range makes rotation rather ineffective as a control measure and resistant crop varieties are not available. Chemical control is the most effective approach. SOIL-BORNE PLANT DISEASES There are a number of soil borne disease that affect crops. These diseases can cause damping off as well as many other plant problems. Pythium The fungi that are responsible for Pythium root rot, also known as black rot or water mold, are present in practically all cultivated soils and attack plant roots under wet conditions. These fungi can be spread by fungus gnats and shore flies. There are many species of Pythium; a few of these species are beneficial in that they compete with or parasitize the pathogenic species. Of the many pathogenic species, some have limited host ranges while others, such as Pythium ultimum, have very wide host ranges. Some Pythium species, such as P. aphanidermatum, are pathogens only at high temperatures (above 77 F), and some are active only at low soil temperatures. Soil moisture conditions of 70% or higher is conducive to infection by the Pythium fungi. Soil from a given field may contain several pathogenic Pythium species. 35
Fig 4.4 Pythium root rot or damping off Pythium species form several types of spores but not all species form all types. Zoospores, which are produced in sporangia, are motile in water. Oospores, which result from a sexual process, usually undergo a period of dormancy and can withstand long periods of drying. Some species also form chlamydospores, which are asexual and have thick cell walls. These structures can serve as resting structures. Sporangia and zoospores in general do not survive in air or dry soil for long periods of time. ELISA test kits are available for detecting Pythium fungi. Symptoms Pythium attacks juvenile tissues such as the root tip. After gaining entrance to the root the fungus may cause a rapid, black rot of the entire primary root and may even move up into the stem tissue. As the soil dries, new roots may be produced and the plant may recover or never show symptoms of disease. Under wet conditions brought about by poor soil drainage or excess irrigation, more and more roots are killed and the plant may wilt, stop growing, or even collapse and die. Bulbs of susceptible plants turn black, gradually desiccate, and form a hard mummy. Phytophthora Phytophthora blight of pepper is caused by the fungus Phytophthora capsici. Other names applied to this disease of vegetables and fruits are damping off and Phytophthora root rot, crown rot, and stem and fruit rot. All of these names can apply since all parts of the vegetable or fruit plant are affected. Figure 4.5 Pytrpthora damage to Tomatoes 36
Epidemiology and disease development The following comments address pepper Phytophthora blight (P.capsici), and in general also apply for diseases of crops listed in the table. The fungus occurs naturally in most soils and can infect pepper and other crops at most stages of growth when there is excess soil moisture and warm, wet weather. The fungus over-winters in soil as thick-walled oospores. For pepper, the fungus also survives on and in infested seed, but this is not a factor with commercially purchased seed. Infected plants produce irregularly branched thread-like structures (sporangiophores) which in turn produce variously shaped sporangia spores. With adequate moisture the sporangia give rise to biflagellate (two-tailed) motile zoospores. These spores produce germ tubes that penetrate plant tissue. The cycle is repeated with the production of more sporangiophores and sporangia. When the humidity is high, the sporangia can survive for long periods. During such times wind-borne sporangia can be carried long distances, causing widespread dissemination and a rapid increase in the disease. Zoospores are readily spread by splashing rain and by flowing irrigation and surface water. The disease develops first in low areas after heavy rains and can quickly spread throughout the field. Favorable conditions for the fungus include wet soils above 65 F (18 C) and prolonged wet periods with air temperatures in the 75-85 F (24-29 C) range (refer to fig.8). Symptoms Phytophthora blight of peppers can attack the roots, stems, leaves, and fruit, depending upon which stage plants are infected. A grower not knowing what to expect might first encounter the disease at mid-season when sudden wilting and death occur as plants reach the fruiting stage. Early infected plants are quickly killed (foreground, while later-infected plants show irreversible wilt. Often a number of plants in a row or in a roughly circular pattern will show these symptoms at the same time. Fungus-infected seedlings will damp off at the soil line, but relatively few plants die when temperatures are cool. Far more commonly, the disease will strike older plants which then exhibit early wilting. Stem lesions can occur at the soil line and at any level on the stem. Stems discolor internally, collapse, and may become woody in time. Lesions may girdle the stem, leading to wilt above the lesion, or plants may wilt and die because Fig 4.6 Phytophthora root damage the fungus has invaded the top branches before the stem lesions are severe enough to cause collapse. Leaves first show small dark green spots that enlarge and become bleached, as though scalded. If the plant stems are infected, an irreversible wilt of the foliage occurs. Infected fruits initially develop dark, water-soaked patches that become coated with white mold and spores of the fungus. Fruits wither but remain attached to the plant. Seeds will be shriveled and infested by the fungus. 37
Because of the wide host range and the various phases at which plants can be infected, refer to the table for clarification of the crops affected and the Phytophthora species involved. The symptoms of buckeye rot of tomato (mainly caused by P. parasitica, consist of leathery tan or brown spots, often appearing as concentric rings or bands on green fruit. Lesions can appear on the shoulder or, more commonly, on the blossom end where the tomato has contact with wet soil. On butternut squash (and on several of the other crops listed with fruit symptoms) tan or brown lesions may give a banding affect or appear as large circular spots. Under humid conditions, white cottony mycelium and spores occur on the surface, and fruit are likely to rot quickly from secondary organisms. WEEDS AND GERMINATION WEED SEED PESTS GRASSY WEEDS There are a number of grassy weeds that are considered pests. These grasses are pests in a nursery as well as a golf course setting. A soil fumigation application will rid the soil of these pest and their germinating seeds. This will allow for better crop growth because the crop will not be competing for moisture or nutrients with the weeds. A few common weeds to Ohio with a brief description are following. Crabgrass Crabgrass is a summer annual grassy weed. Seeds usually begin to germinate in late April to early May. Pre-emergent applications made prior to this time are generally effective in controlling this weed. We often see a good crop of crabgrass and other annual grasses in late summer, as pre-emergent applications begin to weaken and fail. This is why two applications of pre-emergent, properly timed, are usually recommended. A short mowing during summer can also lead to an outbreak of these weeds. Crabgrass dies in the fall. Fig 4.6 Crabgrass Goosegrass Goosegrass is a summer annual grassy weed. It often appears in compacted areas. This weed is commonly seen on high traffic areas at a golf course. It has a white color at the base, and will tend to lie flat when young. It can be controlled with a properly timed pre-emergent application. 38
Fig 4.7 Goosegrass BROAD LEAF WEEDS Broadleaf weeds have many varieties. Some are flowering while others are not. Some are very active in the early spring such are the dandelion. Other broadleaf weeds do not emerge until mid to late summer such as spurge. It does not matter what time of year they are active in nursery plantings, vegetables, greenhouses and golf courses these pests need to be controlled. Dandelion Dandelions are a perennial broadleaf weed. They usually germinate in the fall, and go to seed the following spring. This weed is a very prolific seed producer that can infest a lawn relatively quickly. Dandelions can be easily controlled with post-emergent applications of broadleaf weed control products. As is the case with all weed management, tall mowing is a big help in controlling this weed. Fig 4.8 Dandelion 39
Common Chickweed Common Chickweed is a winter annual broadleaf weed. Chickweed germinates in the fall, and completes its life cycle the following spring. It is most aggressive in shady areas. Like most winter annuals Chickweed can be tough to control because it thrives when the weather is cool, and weed control products aren't usually as effective in cool weather. Fall is a good time to control this plant, but some follow-up treatments may be necessary in spring. Fig 4.9 Common Chickweed Henbit Henbit is a winter annual broadleaf weed. Almost all the information on chickweed applies to this weed as well. It does feature a fairly large purple flower. These plants often produce a mass of short-lived purple blooms in wild areas. They have a square stem, which indicates they are a member of the mint family. Fig 4.10 Henbit 40
RODENT PESTS The Woodchuck (Groundhog) Fig 4.11 Woodchuck Life Cycle and Biology They are the largest of all squirrels and are commonly known as woodchucks or groundhogs. They are distributed across the United States, although there are some regions that don't have any of the six species. Woodchucks are stocky, they weigh 5-15 lbs when mature and have short ears and legs. Woodchucks reproduce once a year. They produce litters that have 4-8 young. In northern states, woodchucks will hibernate. They like to feed in the early morning and late afternoon. However, it is common to see them lying in the sun around their burrows. Woodchuck Damage Woodchuck populations usually don't grow too large yet they mere existence can cause economic damage. They will burrow under the slabs of homes that create structural problems. More damaging are the broken legs and other injuries horses and cattle sustain from stepping in a burrow. This is why horse farms, cattle ranches and any farm which has large livestock must keep woodchuck populations to a minimum. Around the home, most woodchuck problems are due to damage they cause eating plants. Control There are a number of products on the market today for the control of the Woodchuck. It is best to consult with your local extension educator or pesticide dealer in your county. They will be able to get a list of fumigants available for Woodchucks. Always make sure that you follow all the label instructions and wear the right protective equipment when using fumigants. Moles Fig 4.12 Mole 41
Biology and Life Cycle The mole we find the most in Ohio is the Eastern mole. This mole is a mammal classified as an insect eater. Their principle diet consists of live earthworms, grubs, beetles, ants and other insect larvae. Moles are known to have a very high metabolic rate. They have a huge appetite and can usually eat more than their weight in food. Moles produce one litter of two to six young, depending on the health of the female. Pups do not stay under the mother s care for very long. After only a few months of being nourished by their mother s rich milk, the pups will be forced to strike out on their own. Not having the strength of an adult, the pups will often travel in loose soil or even above ground in the treacherous search of their own territory. Moles - Discrediting the Myths There are plenty of myths connected with these creatures. Moles seem mystical and secretive, as they basically spend their life underground. Some people believe moles are blind. This is not true to fact. Their eyes present a thin membrane behind their snout. The mole's eyes sense light. The mole's appetite appears insatiable. It is true to some extent. However, moles do not eat several times as much as they weigh daily. One hundred per cent of their body weight in food equivalent seems enough for them. Contrary to common belief, moles are not nocturnal. It is highly probable that moles work and sleep in 4- hour shifts. Moles are more active late in the evening or in the early morning hours. Moles are unlikely to show when they hear someone walking or when they sense some danger. Control There are a number of products on the market today for the control of the Moles. It is best to consult with your local extension educator or pesticide dealer in your county. They will be able to get a list of fumigants available for Moles. Always make sure that you follow all the label instructions and wear the right protective equipment when using fumigants. 42
Chapter 5 Soil Fumigation Equipment Learning Objectives You should learn: The types of fumigation equipment How to us the fumigation equipment SOIL FUMIGATION EQUIPMENT The following information is on the types of soil application equipment used in the various types of soil fumigations. Drip Irrigation Fumigation Drip irrigation fumigation with a chloropicrin mixed with 1, 3-dichloropropene followed by metam sodium is the most effective chemical alternatives to methyl bromide. Also because these active ingredients are less volatile than methyl bromide they can be applied to raised as well as flat frame beds. Successful drip soil fumigation requires adequate soil preparation, a well-designed drip irrigation system, and dependable chemigation equipment. Drip irrigation fumigation is becoming more popular because the applicator does not have to be present while fumigation is being completed. Fig 5.1Drip Application Equipment Fig. Raised Tarp Application Broadcast Applications Broadcast applications are used for larger areas such as nurseries, sod farms, fruit and vegetable production. There are a few types of application equipment that will achieve the control that is desired. There is single row tarping where soil fumigation will take place under the single row of tarping. There are also multiple rows of tarping that are sealed together where multiple rows can be fumigated at a time. 43
Fig 5.3 Single row tarping Fig 5.4 Multiple row tarping Shank Chisel Soil Fumigation Applications Shank chisel applications (Fig 5.5) are usually used in very large agriculture operations. They are usually applied with a tractor or a vehicle with enough horsepower to chisel through the soil. Fig 5.5 Shank Chisel Shank applications are usually done with liquid fumigants. The fumigant is applied via knife like blades. A tube carrying the fumigant runs down the back of each shank. The soil is sealed or compacted by pulling a ring roller (Fig 5.6) behind the fumigation equipment or behind a second tractor. (Fig 5.7) Different depths of injection and shank spacing are uses for different situations. In general, deeper injections and closer shank spacing provide increased control in well prepared soils but also require a slower speed and more powerful equipment to achieve this increases the cost of the application. 44
Fig 5.6 Roller Ring Fig 5.7 Shank Chisel Application with two tractors BURROWING PEST CONTROL Pellet or Tablet Type Fumigants This product may be applied to underground burrow systems located in non-crop areas, crop areas, or orchards occupied by burrowing pests. All treatments for control of these species in burrows must be made outdoors. Tablets or pellets must be applied directly to underground burrow systems. Before using products tablets or pellets for burrowing pest control, read the applicable restrictions under Environmental Hazards, Endangered Species and Special Local Restrictions below. 45
Fig 5.8 Containers of Aluminum phosphide pellets and tablets This product may be used out-of-doors only for control of burrowing pests. THE PRODUCT MUST NOT BE APPLIED INTO A BURROW SYSTEM THAT IS WITHIN 15 FEET (5 METERS) OF A BUILDING THAT IS, OR MAY BE, OCCUPIED BY HUMANS AND/OR ANIMALS, ESPECIALLY RESIDENCES. Document any burrows that open under or into occupied buildings, and do not apply to these burrows. In addition, check for any other source through which the gas may enter into occupied buildings as a result of application to burrows. If there is any way gas can move through pipes, conduits, etc. from burrows, do not treat these burrows. Prior to treating a rodent burrow on a property containing an inhabited structure, the applicant must provide the customer (e.g. tenant, homeowner, or property manager) with a MSDS or appropriate sections of the Applicator s Manual. Application Directions: Use application procedures appropriate to the type of burrow system being treated. DOSAGE RATES MUST NOT BE EXCEEDED UNDER ANY CIRCUMSTANCES. For species with open burrow systems, locate all entrances to each burrow system. Treatment of more than one entrance in a system is often desirable as systems often overlap and are not defined. Treat all entrances except for those entrances you are sure that connect to already treated entrances. Insert 2 to 4 tablets or 10 to 20 pellets into each entrance to be treated. Use the lower rates for smaller burrows and/or when soil moisture is high. Use the higher rates for larger burrow systems and when soil moisture is relatively low. Pack each treated entrance with crumpled paper and shovel soil to completely cover the paper. Using crumpled paper will prevent soil from covering the tablets or pellets and slowing down their action. Rocks, clods of soil, cardboard, etc. may be used for this purpose. Be sure to seal all untreated entrances by shoveling and packing soil and/or sod to completely seal the opening. Inspect treated areas 1 or 2 days following treatment for signs of residual activity of target species. Treat all reopened burrows in the same manner prescribed above. Species with closed burrow systems (pocket gophers and moles in some situations): Locate the main underground runway by probing with a smooth-sided rod 12 to 18 inches from a fresh mound. For pocket gophers, begin probing on the flat side of the mound. A sudden reduction in soil resistance to the probe 46
indicates that the main runway has been located. Once the main runway is located, remove the probe and apply 2 to 4 tablets or 10 to 20 pellets through the probe hole. Adjust treatment rate according to the level of soil moisture, using more tablets or pellets if the soil is relatively dry. Do not treat if soil is extremely dry or if there are no signs of recent gopher or mole activity. Make a tight seal to close probe hole by using a clod of soil or a sod plug to cover the hole or by using the heel of your shoe to push sod and/or soil over the surface opening. If the probe hole is more than one inch in diameter, place crumpled paper in the hole before closing it with soil and/or sod. Two days after treatment, you may check area for residual pest activity by poking holes in main runways of burrow systems, flagging holes and inspecting them two days later. You should retreat all re-closed systems on both sides of the plug. Gas Cartridge Type Fumigant Gas cartridges that produce poisonous gas (killing by suffocation) are one of the most common methods of woodchuck control. These cardboard cylinders must be ignited and placed in the burrow system. Because of potential fire hazard and gas accumulation in homes, never use a gas cartridge in burrows under homes, tobacco sheds, buildings, dry grass, or near other combustible materials. Fumigation is most effective February through April when the soil is moist because: the burrow can be tightly sealed so little gas escapes through small cracks in the soil, and woodchuck reproduction has not yet occurred. Other factors determining the success of fumigation include the length and configuration of the burrow system, absorption of gas into soil cracks, and inadequate plugging of all burrow entrances. Fig 5.8 Gas Cartridge type fumigants Gas cartridges are safe if the user takes a few precautions. Never use a fumigant in a manner inconsistent with its labeling. Failure to comply with directions may subject you to severe federal or state penalties. Gas cartridges must be ignited by lighting a fuse. They are not bombs and will not explode if properly prepared and used. Follow these precautions before using a gas cartridge: Before lighting the fuse, ensure that the cartridge will pass easily into the burrow entrance. Always light the end of the fuse, never the cartridge directly. Do not hold a burning cartridge in your hand. Once the fuse has been lit, work quickly because burn time may be less than five seconds. Place the fuse-end of the cartridge into the burrow first. Avoid prolonged breathing of smoke, and handle cartridges carefully because ignited gas cartridges can cause severe burns. 47
Chapter 6 Characteristics of Fumigants Learning Objectives You should learn: Characteristics Volatility Molecular Weight Boiling Point Vapor Pressure Specific Gravity Diffusion (Flow) Potential Water Solubility Latent Heat of Evaporation Flammability Chemical Reactivity CHEMICAL AND PHYSICAL CHARACTERISTICS Important physical and chemical characteristics of a fumigant include volatility, molecular weight, boiling point, vapor pressure, specific gravity, diffusion potential, water solubility, and latent heat of vaporization, flammability, and chemical reactivity. Read the product information supplied by the manufacturer to be sure that the material you select is appropriate to the commodity, treatment site, and target pest. The label must list the commodity and target sites. Volatility Volatility is the tendency of a chemical to evaporate and become a gas or vapor. Volatility increases as temperature rises. Some "gaseous-type" fumigants, such as methyl bromide, are normally a gas at room temperature. Other fumigants exist as a liquid or solid at room temperature. Also, many of the "solidtype" fumigants, such as aluminum phosphide, are not fumigants themselves but react with moisture to form a fumigant gas (phosphine or hydrogen phosphide). Molecular Weight Molecular weight is a measure of the weight of the atoms that form the fumigant molecule. More complex molecules have greater molecular weight because they have more atoms. Larger molecules are often less suitable as fumigants, since they are less volatile. Boiling point The boiling point of the chemical is the temperature at which the liquid stage boils under specific atmospheric conditions to become a gas. Some materials used as fumigants, such as methyl bromide, have low boiling points so they are gases at normal temperatures and atmospheric pressure. These types of fumigants are usually stored as liquids under high pressure. The boiling point of a fumigant may influence the type of application equipment required. For example, fumigants with low boiling points usually require heaters to warm the gas as its being released. This is 48
because these materials may freeze on release into the atmosphere, since much heat is lost as fumigants turn from a liquid to a gas. They diffuse more slowly, and it may be important to disperse these types of gases with fans or blowers. Vapor Pressure Water The vapor pressure of the fumigant affects the atmospheric concentration of the gas in the air. When a volatile liquid or solid is confined in an area, equilibrium gradually takes place between molecules in the gas and liquid phases. Once the gas molecules reach a saturation point, further volatilization won t increase the number of molecules in the vapor phase. Although volatilization may appear to stop, what actually happens is that a gas molecule condensing back to the liquid form replaces every molecule evaporating from the liquid. Methyl bromide probably cannot revert to a liquid at normal pressure. Since vapor pressure determines the concentration that can be maintained during fumigation, materials of high vapor pressure will be more concentrated and therefore have better fumigant qualities. Specific Gravity The specific gravity of a chemical compound is a measure of its weight in a given volume. With fumigants, it s important to know if the gas is lighter or heavier than air. Most commonly used fumigants are heavier than air. A heavy gas in a confined area will tend to concentrate in low areas and mix slowly with the air. Hydrogen cyanide was the only gas lighter than air. These fumigants usually require mechanical mixing with a fan to distribute the molecules evenly through the fumigated area. However, once the fumigant is thoroughly mixed with the air settling takes place very slowly. As a result, the problem of stratification or layering, of heavier than air fumigants doesn't have much practical meaning for the exposure periods usually required in fumigation work. All gases become lighter as they become warmer. This is because warm molecules take up more space; so fewer molecules can be contained in a given space at the same pressure. Diffusion (Flow) Potential Diffusion or flow potential is a measure of how fast gas molecules disperse through the atmosphere. After a while, the molecules become evenly distributed. The speed with which molecules disperse is affected by the molecular weight of the gas. Gases that are heavier diffuse more slowly and it may be important to disperse these types of gases with fans or blowers. Water Solubility The water solubility of a fumigant becomes an important consideration if items in a fumigated area contain even small amounts of water. The water will tie up water-soluble fumigant molecules, reducing the fumigant concentration in the atmosphere. Toxic molecules also may be incorporated into the water of fumigated materials and may remain as undesirable residues. Suitable fumigants for most applications are those that are insoluble or only slightly soluble in water. Latent Heat of Evaporation Latent heat of evaporation (the extra heat required to change the liquid to a gas) must be considered when using fumigants that have boiling points below room temperature. Unless sustained by warming from an outside source, the temperature of an evaporating liquid constantly drops. This is shown by the cooling effect of evaporating water on the skin. 49
The factor of latent heat has important practical significance. High-pressure fumigants volatilize and lose heat rapidly on release. Unless the lost heat is restored, the temperature of the fumigant may fall below its boiling point, causing the gas to no longer evolve. Also, as the liquid changing to gas is led through metal pipes and tubes or plastic tubing, the drop in temperature may freeze the fumigant in the lines, preventing further passage. In many applications, it's wise to apply heat to the fumigant as it passes from the container into the fumigation space. Fumigants that are liquids at normal temperatures and are volatilized from evaporating pans or vaporizing nozzles also lose heat. These applications may require a source of heat, such as a hot plate, so that full concentrations will take place rapidly. Flammability Flammability of a fumigant is another physical characteristic that is very important in its safe use. Fumigants that are flammable gases are usually combined with a non-flammable gas (such as carbon dioxide) to reduce the danger of fire or explosion. Chemical Reactivity Chemical reactivity of some fumigants with other chemicals in the environment may limit some fumigant uses. Phosphine gas reacts with copper, silver and gold (or their alloys used in electrical wiring, motors and computers) to cause serious corrosion. High temperatures around an open flame may cause some fumigants to form corrosive acids. Certain fumigants may make photographic film and paper unusable because of chemical reaction. READ AND FOLLOW INSTRUCTIONS ON THE LABEL. 50
Chapter 7 Types of Fumigants Learning Objectives You should learn about: Product Stewardship - What is it? The types of fumigants Their characteristics How fumigants affect insects PRODUCT STEWARDSHIP - WHAT IS IT? Most registrants of fumigation products are committed to exercising responsible care for their products in manufacturing and distribution and later, in the handling of their products by distributors, dealers and use by its customers. This means assessing the environmental impact of the products and then taking appropriate steps to protect employee and public health and the environment as a whole. In addition to safe production, stewardship means they have a continuous concern for the proper use and ultimate disposal of their products. Most registrants will be offering training programs for persons using their products. These training programs will need to be completed by the product users, to purchase many of the fumigants. The staff at the Ohio Department of Agriculture along with the USEPA is in favor of these stewardship programs. TYPES OF FUMIGANTS Many of the active ingredients in fumigants used in the early days of fumigation have either been canceled entirely or had their uses restricted. All space-fumigation products and several soil-fumigant products (especially those containing chloropicrin and/or methyl bromide) are now restricted-use pesticides. The active ingredients that are still legal to use in Ohio include: Methyl Bromide Methyl bromide is a colorless, odorless and tasteless gas. It is heavier than air, so it tends to settle out in low places. It also tends to stratify so fans are needed to assure thorough mixing of the gas with the air. It penetrates most commodities very well, and is effective against all stages of insect life. Methyl bromide is one of the top five most widely used pesticides in the world today. Eighty seven percent of methyl bromide is used by farmers prior to planting to eradicate all fungus, nematodes, microorganisms, and weeds from the soil to avoid destruction of the crop. In the U.S., methyl bromide is used mainly for tomato, strawberry, and bell pepper crops. California is the largest user, followed by Florida. As with all other fumigants, methyl bromide is toxic to all forms of animal life. Additionally, repeated exposure to low doses of methyl bromide may accumulate in body tissue. The established threshold limit 51
of methyl bromide daily exposure is 5 parts per million (PPM). (The threshold limit is the maximum permitted daily exposure, eight hours per day, five days per week). When handling methyl bromide, you must have respiratory protection. Only SCBA will give adequate protection. Methyl bromide is a fumigant that has many registered uses. READ THE LABEL. It may be used to control insect pests in a wide variety of food products. It has registration and established tolerances for use in a large variety of grains, fruits and vegetables. Be sure your pest problem is included on the label. Methyl bromide is supplied in steel cylinders of several sizes. In these pressurized containers, methyl bromide is a liquid. Once the pressure is released, the liquid vaporizes to a gas. The material may be supplied either as 100% methyl bromide or as 98% methyl bromide plus chloropicrin. The chloropicrin (tear gas) serves as a warning agent. Not all of the uses registered for the 100% material are included on the odorized methyl bromide label. The methyl bromide in small cans is ideal for small jobs. With these cans a special applicator is required. The applicator punctures the can, and polyethylene tubing will conduct the methyl bromide into the fumigation enclosure. Heating of the fumigant usually is not necessary. Some leakage can occur around the gasket of the applicator. Hold can away from body. There may be a small amount of gas left in the can when removed from the applicator. Toss a short distance downwind and pick it up later. Methyl bromide in cylinders is usually used for larger fumigations. Special heat exchangers can be purchased or made on the job. Copper tubing is attached to the cylinder by a gas tight fitting. This tubing is then formed into a 25-foot coil that is immersed into a container of water heated to 150 F. The tubing from the heater to the fumigation chamber may be either copper or polyethylene. The fewer fittings you have the better. It is most difficult to keep the fittings from leaking methyl bromide. As methyl bromide is heavier than air, the outlet of the introduction tube should be placed high within the fumigation enclosure and with a fan in back of it. Release gas slowly so that proper heating will be obtained. When methyl bromide changes from a liquid to a gas, it becomes very cold, and even though the gas has been heated, there is a chance that the low temperature created will change a part of the gas back to the liquid state. For this reason, a pan should be placed directly beneath the outlet end of the tubing to protect the commodity from dripping methyl bromide. When gas drips down a cylinder, it can remove paint from the cylinder and stain the floor. Liquid methyl bromide is a good solvent and will harm any plastic, painted surfaces, tile floors or other susceptible surfaces with which it comes in contact. The use of fans behind the nozzle outlet and the use of a drip pan can help avoid these problems. After you have calculated the amount of methyl bromide required, the cylinder is placed on scales and weighed. From the total weight, subtract the weight of the fumigant required and set the new weight on the scales. When the scale beam balances you have introduced the correct amount. Fumigation with methyl bromide is relatively quick. An exposure of 24 hours or less is usually adequate. When the cylinder is opened outside, SCBA is not required but eye protection such as a face shield is required. A SCBA should be available and ready for use if the need should arise. Aprons may be worn but loose fitting clothes that can be quickly removed in case of an accident are preferred. Gloves should not be worn because they could trap gas against the skin causing burns. If methyl bromide should be spilled on shoes, take them off. Methyl bromide trapped in shoes will cause serious blistering. Once the methyl bromide has been introduced, you should check for leaks. The Halide gas detector has a flame that 52
heats a copper ring. Methyl bromide gas (as well as fluoride, chlorine and the freons) passing over the heated copper ring will be colored. The depth of color will depend on the gas concentration. A very light green indicates a low concentration. A royal blue color indicates a high gas concentration. New electronic leak detectors are more expensive but have many advantages. All leaks must be repaired when found. There are a number of items that should not be exposed to methyl bromide. Some react with the gas and create long-lasting odor problems. The gas may actually damage other items. The label is the best guide but when in doubt, test a small amount of the commodity in a chamber such as a steel barrel using the concentration of gas that is planned. Check for rancid odors after the test fumigation. Chloropicrin Chloropicrin fumigant products contain nearly 100-percent chloropicrin and are marketed as liquids. Chloropicrin volatilizes to form a dense gas that is about 5.7 times heavier than air. Chloropicrin is highly toxic to insects, vertebrates, and many soil microbes, such as fungi. It s highly irritating to eyes and is a powerful "tear gas." Concentrations as low 1.0 part per million (ppm) cause intense eye irritation, and prolonged exposures can cause severe lung injury. Chloropicrin can cause severe injury upon skin contact. The use of chloropicrin is prohibited on food. It can be used as a warning agent with methyl bromide treatment of houses where all foods have been removed. It can also be used on empty grain bins. Sodium Methyldithiocarbamate (Metam Sodium) Metam sodium can be used for many different types of cultivation, including: Root crops such as carrots, potatoes, peanuts, beets Vegetable crops like lettuces, cucurbits, onions, leaks, tomatoes, cabbages. Strawberries Tobacco Tree nurseries Vineyards and orchards Ornamentals like cut flowers, bulbs, perennials Tropical crops like bananas, pineapples A good application technique is the key to good and lasting disinfection. Soil preparation for sowing or planting must be done before treatment. Metam sodium may be applied by injecting it into the soil; after treatment the soil must be packed down and covered, to prevent the metam sodium from evaporating too quickly. The product may also be applied directly, by drip irrigation, by dilution with water, and in some particular cases by spraying onto the soil, and quickly working it in. It is also possible to incorporate the product into the soil without digging, by spraying with large quantities of water (10-20 liters per m²). 53
After the soil has been treated, it must be left for 2-4 weeks (depending on the type of soil, the temperature and the moisture of the soil). Decomposition of any product still remaining in the soil after that time can be accelerated by aeration. After the soil has been treated, it must be left for 2-4 weeks (depending on the type of soil, the temperature and the moisture of the soil). Decomposition of any product still remaining in the soil after that time can be accelerated by aeration. Since methyl isothiocyanate is phytotoxic, planting may not take place until the product has completely decomposed and the treated soil has been fully aerated. In order to decide when planting can take place, a sowing test (cress test) on a representative sample of the treated soil is recommended. 1.3-Dichloropropene 1.3-Dichloropropene has been registered as a pesticide in the U.S. since 1966. It is a general biocide, and is primarily used to kill nematodes. It can also be used for plant diseases, insects and weeds on potatoes, tomatoes, tobacco, vegetables and orchard crops. In 1989, the U.S. Environmental Protection Agency (EPA) estimated that between 35 and 45 million pounds of 1,3-dichloropropene was used annually in the U.S. 1,3-Dichloropropene kills nematodes in a similar manner as methyl bromide and chloropicrin. The 1,3dichloropropene molecule reacts with an unidentified vital enzyme system (or systems) at a site on the enzyme containing sulfhydryl (sulfur + hydrogen), ammonia, or hydroxyl (oxygen + hydrogen) ions. A substitution reaction occurs in which the 1,3-dichloropopene molecule minus one of its chlorine atoms replaces one of the hydrogen atoms on the enzyme. As a result, the enzyme ceases to function properly. Hyperactivity of the nematode then occurs, followed by paralysis and death. People exposed occupationally or from spills to 1,3-dichloropropene have suffered chest pains, coughing and breathing difficulties, and skin rashes. Irritation of the eyes and respiratory tract, liver, kidney damage and cardiac arrhythmias are also symptoms of 1,3-dichloropropene exposure. 1,3-dichloropropene is a preplant soil fumigant for control of all major species of nematodes. These include root knot, lesion, stubbyroot, dagger, ring and cyst nematodes. 1,3 dichloropropene is injected into the soil as a liquid and immediately converts to a gas. It creates a zone of protection around developing roots. As a fumigant, 1,3-dichloropropene moves throughout the soil profile on its own, rather than requiring water or incorporation for movement. 54
Appendix A F U M I G A T I O N M A N A G E M E N T P L A N for Burrowing Pests (SAMPLE not applicable for all situations) The purpose of this SAMPLE Fumigation Management Plan is to assist Ohio applicators to insure the safety of their community and the environment. It is also designed to ensure an effective fumigation and to assist in meeting phosphine label requirements. Land Owner/Manager: Name: Address: Day Telephone Number: City: Zip: Night Telephone Number: Email: Certified Applicator(s) in Charge: Name: Address: Day Telephone Number: City: Zip: Night Telephone Number: Email: Company: Phone: Certification # Date of Expiration: Name: Address: Day Telephone Number: City: Zip: Night Telephone Number: Email: Company: Phone: Certification # Date of Expiration: Carry a copy of DOT-E 11329 (placarding exemption) for transport of no more than 21 KG of phosphide product in motor vehicle without placards. Vehicle has DOT placards Emergency Telephone Numbers: Local Police: Local Fire: Local Hospital: Sheriff s Office: Chemtrec: 1-800-424-9300 Poison Control: 1-800-222-1222 55
Reason for Fumigation (elimination of rodent infestation, etc.): Fumigation Type : In Burrow Pest: Woodchuck, yellowbelly marmot, prairie dog, Norway rat, roof rat, mice, ground squirrel, mole, vole, pocket gopher, chipmunk Date or referred to previous FMP dated: Site Fumigation history: Description of Fumigation site: Attach detailed drawing (identify any nearby inhabited structures). Mark burrows which open under or into occupied buildings & do not apply to these burrows. Mark points of fumigation application. Consulted with land owner/manager in developing FMP on (date). Confirmed treated burrow system is in excess of 15 ft. of any occupied building. Checked for other sources through which gas may enter occupied buildings (pipes, conduit, etc.). If property contains an occupied building, owner/manager was provided with a MSDS or appropriate sections of Applicators manual on (date). Prairie dog habitat covers less than 80 acres of black-tailed prairie dog towns and has no neighboring towns (within 4.34 miles). Prairie dog habitat covers 80 acres or more. Obtained the Pesticide use Bulletin for Protection of Endangered Species for county. Contacted U.S. Fish & Wildlife Services concerning Black-footed Ferret Survey Guidelines for compliance with the Endangered Species Act on _ (date). Black-footed ferret survey conducted on (date) by. Consulted with land owner/manager in procedures for notifying local authorities on. Notified local authorities on (date). Work to be performed: Site to be fumigated Refer to site diagram Dosage 56
Personnel Training for parties who will be in immediate area during/after fumigation: Instructed Fumigators on product Label on_ (date). Instructed Fumigators on Applicator s Manual on (date). Instructed Fumigators on required PPE on (date). Instructed on Untreated burrow entrances to be Sealed: List and/or indicate on site diagram. Untreated burrow entrances sealed (date). Treated burrow entrances to be Sealed: List and/or indicate on site diagram. Treated burrow entrances sealed (date). Sites in or by occupied building to be Monitored to demonstrate residents will not be exposed to gas concentrations above allowable limits.: List and/or indicate on site diagram. Site Number Date Time of Readings Phosphine Reading(s) Treated site reinspected for target species on (date). Notified appropriate people when it is safe to reenter treated sites on ( date). Attach a copy of an Emergency Plan. Include a written procedure with instructions of who to contact and how if phosphine levels are exceeded in an area that could be dangerous to local residents. 57
Dec. 2006 Ohio Department of Agriculture Certification & Training Program 58