Chapter 13 Pesticides.
After studying this chapter, the student should be able to
* Discuss the different types of pesticides and formulations available to the turf manager
* Explain the process of pesticide applicator certification mandated by the
Environmental Protection Agency
* Describe the fate of pesticides in the environment
* Discuss pesticide toxicity and methods of measuring toxicity
* State why it is important to read a pesticide label and follow the directions on the label
* List the protective clothing that must be worn when handling various pesticides
* Identify the symptoms of pesticide poisoning
* Describe safe methods of pesticide storage
A turfgrass pest is defined as any organism that causes a decrease in turf quality. These pests include fungi and other microorganisms that cause turf diseases, insect and nematode species that feed on turfgrass (Figure 13-1), and weeds. A pesticide is a toxic chemical that destroys pests. Pesticides are controversial because of problems that can result from their misuse. It is important that turf managers be knowledgable about pesticides so they can protect themselves and the environment if they use them. Methods of reducing pesticide use are explained in Chapter 17, which discusses integrated pest management techniques.
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Types of Pesticides
A number of different types of pesticides are used to control various pests. Insecticides are chemicals used to control insects. Most insecticides kill the insect pest by disrupting its nervous system. These toxic chemicals enter the insect's body when it comes into contact with the insecticide. A second type of insecticide acts as a stomach poison and must be ingested (swallowed) by the insect to be effective. Some insecticides work both ways. Insecticides are often the most dangerous type of pesticide because humans and insects have certain biological similarities. A chemical that is lethal to insects can also be injurious to humans because of these similarities. Some insecticides will kill mites, but many do not. Miticides are pesticides that are developed specifically for mite control.
Fungicides control fungi, microorganisms that can cause plant diseases (Figure 13-2). Bactericides kill bacteria, another type of microorganism that can incite plant diseases. Antibiotics are substances produced by microorganisms that inhibit or destroy other microorganisms. Some of these chemical compounds are sold commercially and can be used to control plant diseases.
Herbicides control unwanted plants. These chemicals are also called weed killers. Nonselective herbicides are toxic to all plants; selective herbicides kill some plants, but do not seriously affect others. Herbicides usually control either broadleaf plants or grassy plants. Preemergence herbicides are applied before a weed species appears in the turf. They kill the seedlings before their emergence from the soil. Postemergence herbicides are used after a weed has appeared in the turf area.
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Nematicides control nematodes, tiny wormlike animals that usually live in the soil and feed on plant roots. Rodenticides control rats, mice, and other rodent pests.
Systemic pesticides enter a plant and spread internally by moving through the vascular system. They are absorbed by the roots or leaves. Most herbicides are systemics. Some insecticides and fungicides also work systemically. Systemics protect turfgrass for a longer period than nonsystemics because once they enter the plant they will not be washed away by rain or irrigation water and are not subject to decomposition by sunlight or microorganisms.
One advantage of systemic fungicides is their ability to control disease-causing organisms already established inside the plant (Figure 13-3). Systemic insecticides are beneficial because they primarily kill the destructive insects feeding on the plant rather than indiscriminately poisoning all insects. It is important to save as many beneficial insects as possible. They will help to keep insect pests under control. Systemics can also move into and protect plant tissue produced after the pesticide application.
Toxic chemicals used for pest control are often unsafe to handle or difficult to apply in their pure form. The manufacturer must mix or dilute the toxic active ingredient, called the toxicant, with other materials to make it safe and easy to spread evenly over the area to be treated. The toxicant is formulated in liquid or dry carriers by combining it with materials such as solvents, wetting agents, granules, or powders. The final product is called the pesticide formulation. All formulations used on turfgrass, except for granulars, are mixed with water and applied with a sprayer. Fertilizer spreaders are used to apply granular formulations. A single pesticide is often sold in several different formulations. The formulations described here are those commonly used by turfgrass managers. The list will change as chemists develop new and better formulations.
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Granular (or Granule) Formulations (G)
Granular formulations (abbreviated as G) are dry materials that are easily spread using a seeder or a fertilizer spreader. The pesticide is coated on or absorbed by particles of clay, vermiculite, corn cobs, walnut shells, fertilizer granules, or other solid carriers. Most granular formulations have a low concentration of pesticide. The toxicant is released by moisture. When the granules become wet the pesticide is washed off or out of the carrier. Granulars are normally used to treat the soil or thatch. Most do not stick to foliage; liquid sprays adhere to leaves better than granules. Systemic pesticides that enter the turfgrass plant by root absorption are effectively applied in granular form. In some products the toxicant is mixed with fertilizer nutrients.
The remainder of the formulations to be discussed are mixed with water and applied as a liquid (Figure 13-4). For the pesticide to be sprayed evenly over the turf area the chemical must be diluted uniformly in water. The pesticide must be concentrated equally throughout the mixture. The pure form of the toxicant usually does not mix properly with water. Various chemical additives must be combined with the toxicant to achieve a uniform mixture. Some of these formulations dissolve in water and form a solution. Once it is in solution, the pesticide remains equally dispersed in the water and will not settle out of the mixture. Few active ingredients are water soluble.
Most formulations produce a mixture called a suspension. A pesticide in a suspension remains uniformly concentrated when the mixture is agitated. If the mixture is not in motion the pesticide will settle out. The turbulence necessary for agitation can be provided by the movement of a mechanical paddle located in the sprayer tank. Another method of agitation involves the recirculation of the mixture from the pump back into the tank. The pesticide mixture streams through a hose into the tank, keeping the tank contents in constant motion whenever the sprayer is operating.
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Emulsifiable Concentrates (EC or E)
The toxicant in an emulsifiable concentrate is oil soluble but not water soluble. It is dissolved in a petroleum solvent such as xylene. An emulsifying agent is added to the petroleum-pesticide solution to enable the pesticide-containing petroleum to mix with water. The result is a relatively stable, milky suspension called an emulsion. Tiny oil globules are dispersed uniformly throughout the mixture. Some agitation may be necessary to maintain this uniform dispersal. Emulsifiable concentrates usually contain a high concentration of active ingredient. They may occasionally injure plants if misused because the oil solvent can be phytotoxic (injurious to plant tissue).
Wettable Powders (WP or W)
These preparations are sold in a dry, flourlike, powdered form. The toxicant exhibits low solubility in water. It is combined with a filler such as clay or talc and a wetting agent. The wetting agent allows the pesticide to be dispersed as a suspension in water. The mixture must be continually agitated to prevent the wettable powder from settling out (Figure 13-5). A wettable powder can be washed off foliage more rapidly than an emulsifiable concentrate.
[FIGURE 13-5 OMITTED]
Flowables (FL or F)
Flowables, like wettable powders, are pesticides manufactured as solid materials only. However, a flowable is sold in a liquid form. The very finely ground powder is suspended in a small amount of water or oil. The liquid paste, or slurry, that is formulated is easier to mix with water in a spray tank than a wettable powder because the pesticide in a flowable is already fully wetted. Flowables require moderate agitation to maintain a uniform tank mix.
Dry Flowables (DF)
A dry flowable is like a wettable powder but the active ingredient is prepared in small granule-sized particles. These particles are easily measured and mixed, and there is less inhalation hazard than with a wettable powder. Some dry flowables are called water-dispersible granules (WDG).
Soluble Powders (SP)
These dry powders are highly soluble in water. The pesticide dissolves in water and forms a stable solution. No agitation is required after the soluble powder is mixed with water in the spray tank.
Soluble Liquids (SL)
These liquid preparations are also highly water soluble and form a stable solution in the spray tank that does not require agitation (Table 13-1).
A few other formulations are occasionally used by the turf manager. Salt concentrates are formulated by producing a chemical reaction that changes a water-insoluble pesticide into a salt. The resulting salt form of the pesticide is highly water soluble. The widely used broadleaf weed killer 2,4-D is manufactured in a salt concentrate formulation. Fumigants are pesticides that form a gas when applied. Turf managers may fumigate a soil before establishment to kill pests such as nematodes. Poison baits are a mixture of pesticide and a food that is attractive to pests such as slugs, mole crickets, ants, grasshoppers, or yellowjackets. The pest eats the bait and is poisoned.
Adjuvants are chemical additives that improve the performance of a pesticide. Two types of adjuvants that allow the toxicant to mix with water have already been mentioned--wetting and emulsifying agents. Three other types commonly added to pesticide formulations are stickers, extenders, and spreaders. Stickers increase the initial adherence of the pesticide to foliage and enable it to remain there for a longer period of time. Without stickers rain or irrigation water may wash the pesticide off leaves too quickly for it to be effective. Extenders act like a sun screen, protecting the chemical from photodegradation by ultraviolet light. Spreaders help the toxicant to spread evenly over treated surfaces. A pesticide combined with a spreader will form a thin film and cover more leaf surface area (Figure 13-6). Drift-control agents reduce the number of very fine spray particles that are most susceptible to drifting off target.
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The Fate of Pesticides
To be effective against turfgrass pests, the pesticide must be applied to the target zone in the turf where the pest is found. It must then retain its toxicity for a long enough period to control the pest. Drift, the movement of spray droplets by wind, may result in an insufficient concentration of pesticide reaching the target zone. Drift not only reduces the uniformity of spray coverage; it can also lead to problems in the surrounding environment. This is especially true if a herbicide drifts to desirable plants nearby and damages them. Pesticides normally should not be sprayed when the wind speed is greater than a few miles per hour. Early morning and evening are usually less windy than other times of the day.
Water can also remove the pesticide from the target zone. The chemical may be washed off treated foliage. Pesticide runoff occurs when water moves the chemical across the surface of the turf. Runoff is most common on slopes. Leaching is a process that occurs when rain or irrigation water carries the pesticide downward in the soil. The result is a lower concentration of pesticide near the soil surface. Some leaching is desirable if the pest inhabits the soil or if the pesticide is a systemic that must be taken in by plant roots. Too much leaching, however, not only moves the chemical below the target zone, it may lead to contamination of water supplies if the pesticide is carried down to the groundwater.
Volatilization is another process by which the pesticide can move from the target zone. When a chemical volatilizes, it changes into a gas and diffuses into the atmosphere (Figure 13-7). This loss results in reduced pest control and is a serious problem if herbicides in a gaseous state are carried by the wind to sensitive plants. Volatilization is most common at higher temperatures.
Even when a pesticide remains in the target zone, it eventually loses its ability to kill pests. Some pesticides retain their toxicity for only a short time. Chemicals that have a brief residual effectiveness are said to be nonpersistent. Pesticides that retain their toxicity for a long period are said to be persistent. The long-lasting pesticides can be desirable, since fewer treatments may be required because of their persistence. However, pesticides that linger too long in the environment can build up in the food chain and cause other environmental problems.
There are several reasons why pesticide residues (deposits) lose their toxicity. Chemicals adhering to foliage are broken down by sunlight. This process is called photodecomposition. Adsorption and microbial degradation occur in the soil and thatch. Adsorption is a process by which pesticides bind tightly to soil particles or thatch and are inactivated. The rate of adsorption increases in soils with high clay or organic matter contents. Microbial degradation is the breakdown of pesticides by microorganisms that use certain components of the chemicals as a food source. Decomposition by microorganisms is the major reason for the disappearance of pesticides from the environment.
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Various chemical reactions can occur that result in the inactivation of these toxic chemicals. For example, the pesticide can be transformed by hydrolysis when it reacts with water in the soil. Some pesticides are affected by pH and will begin to break down in the spray tank if mixed with water that has an incompatible pH. Most pesticides should not be kept in a sprayer overnight because the mixture may become unstable.
The possible contamination of groundwater by pesticides is a serious concern. A number of pesticides, including some used on turf, have been found in groundwater. It is important to understand why this can occur.
Certain characteristics of a pesticide can be used to predict whether it is likely to move down to the water table. Chemicals that have a long half-life may reach groundwater before they are degraded. Some are so persistent that they are still found in groundwater years after their use was discontinued. Pesticides that are very water soluble can readily move downward in the soil. The degree to which a pesticide is adsorbed to soil particles or thatch is significant. Some are held tightly and do not move.
A pesticide that is used frequently and at high application rates is more likely to cause problems. Soil texture and structure have a significant impact on pesticide movement. Leaching is more common in well-drained soils. Other important factors include the amount of irrigation and the distance from the soil surface to the groundwater.
There are also major concerns about pesticide runoff into reservoirs, lakes, and rivers. Protection of drinking water has become a top priority of government agencies and environmental groups. Further restrictions on pesticide use will occur, especially in areas with sandy soils and fragile aquifers.
Pesticides can be hazardous to both the environment and people. Some can kill or seriously injure people; others are fairly safe. All can be dangerous if misused. Even relatively nontoxic pesticides may cause skin irritations.
To poison or injure people or animals, the pesticide must be on or in the victim's body. Thus, the applicator should never allow the chemical to come into contact with his or her body. Pesticides enter the body by three routes: oral contact, dermal contact, and inhalation (Figure 13-8). Oral contact occurs when a pesticide is swallowed accidentally, usually by children. Oral entry often results in serious injury. Dermal contact occurs when a pesticide contacts the skin. Many chemicals can be absorbed through the skin. Pesticides are readily absorbed through skin on the neck, groin, feet, armpits, hands, and wrists. Contact with the eyes or a cut or scrape also results in rapid pesticide entry. Dermal contact is the most common entrance route. Inhalation occurs when a person breathes in a pesticide. Gaseous vapors or very fine dry particles of pesticide in the air can be inhaled through the mouth or nose.
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Types of Toxicity
Acute toxicity is a measure of how poisonous a pesticide is in a single exposure. The acute toxicity of a pesticide indicates how great the immediate danger is to a person after exposure to the chemical. Chronic toxicity is a measure of how poisonous a pesticide is after repeated exposures over a period of time. Some pesticides accumulate in the body and can eventually cause cancer or other serious problems. A person may handle pesticides for many years before the physiological disorders associated with chronic toxicity become apparent.
Measuring Acute Toxicity
Acute toxicity is relatively easy to measure. Test animals such as rats or mice are exposed to various concentrations of a pesticide, and their death rate is observed. Acute toxicity is measured by determining an [LD.sub.50] value. The LD stands for lethal dose--the amount of pesticide required to cause death. The 50 means that 50 percent of the test animals are killed by this dose. The [LD.sub.50] value is expressed in milligrams of pesticide per kilogram of test animal body weight (mg/kg). This metric measurement is the same as parts per million (ppm). If the [LD.sub.50] of a pesticide is 250, this means that a dose of 250 mg of the chemical per kilogram of body weight (or 250 parts of pesticide for every one million parts of body weight) results in the death of 50 percent of the test animal population.
The lower the [LD.sub.50] number, the more poisonous the pesticide. A chemical with an [LD.sub.50] of 10 is 100 times more toxic than a substance with an [LD.sub.50] of 1,000. [LD.sub.50] values are established for both the acute oral and acute dermal toxicity of a pesticide. Acute inhalation toxicity is measured by [LC.sub.50] (lethal concentration) values. The [LC.sub.50] is expressed in milligrams of pesticide per liter of air. A liter is a metric measurement of volume approximately equal to one quart. The lower the [LC.sub.50] number, the more poisonous the pesticide.
Label Warning Statements
To alert pesticide users to the acute toxicity of a pesticide, a signal word must appear on the label on the pesticide container. Pesticide products are categorized as highly toxic, moderately toxic, slightly toxic, or relatively nontoxic. This decision is based on both the acute toxicity of the active ingredient and its concentration in the formulated material. For example, a product containing a small amount of highly toxic active ingredient may be less toxic than a product containing a high concentration of lower toxicity active ingredient. The category in which the pesticide is placed is indicated by the signal word on the label (Table 13-2). All pesticides need to be handled safely; however, those identified by the signal words DANGER--POISON must be handled with extreme care (Figure 13-9). Fortunately, very few pesticides used on turf are highly toxic.
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Measuring Chronic Toxicity
Chronic toxicity is the result of repeated exposure to pesticides. It is usually impossible to predict the rate of accumulation of a pesticide in the body and its eventual effect on the health of the individual. There is no standard measure like [LD.sub.50] for chronic toxicity. The symptoms of chronic toxicity may take years to develop, and laboratory test animals seldom live long enough for its effects to be determined. Some pesticides are known to be carcinogens, but information such as how many exposures to a chemical result in cancer is difficult to establish because other factors influence this disease as well.
One type of chronic toxicity can be measured accurately by blood tests. Organophosphates and carbamates, two groups of chemicals used to control insect, mite, and nematode pests, disrupt the nervous system by inhibiting an enzyme called cholinesterase. This enzyme breaks down acetylcholine, a chemical involved in the transmission of nerve impulses. If acetylcholine accumulates in the body, serious nervous system disorders can occur. Constant exposure to organophosphates or carbamates can result in a decline in cholinesterase activity and a buildup of acetylcholine. Applicators who use these chemicals regularly should arrange for blood tests to determine cholinesterase levels. If the level is too low, the applicator should avoid further exposure to these pesticides until the body regenerates sufficient cholinesterase.
In 1996, Congress passed the Food Quality and Protection Act. One of the concerns addressed in this legislation was the possible impact of pesticides on the developing nervous and endocrine systems of infants and children. The Environmental Protection Agency evaluates the potential aggregate (combined) exposure to pesticides from sources such as fruits, vegetables, grains, and other foods; drinking water; lawn and garden chemicals; pet treatments; etc. (Figure 13-10). The agency is required to determine whether there is a reasonable certainty of no harm from aggregate exposure. If there is a possibility of harm (neurological problems, cancer, etc.), then the exposure to pesticide residues must be reduced. One reduction method is to restrict or suspend the use of pesticides such as the organophosphates, which present the greatest potential risks. Consequently, the selection of insecticides that are available to the turf manager has changed significantly in recent years.
Pesticide Applicator Certification
In the 1970s the Environmental Protection Agency (EPA) became increasingly involved in the regulation of pesticide use because of the potential threat of pesticides to the environment. This federal agency set standards for the handling and use of pesticides. States were required to develop and administer pesticide applicator certification programs. To be allowed to purchase certain hazardous pesticides, an applicator must first pass a written test that requires a basic knowledge of pesticides and their use. Restricted-use pesticides have a high acute toxicity or pose a significant environmental risk because of their persistence or tendency to leach. A certified pesticide applicator must be recertified every few years. This is usually accomplished by attending workshops, conferences, or other activities at which the applicator receives pesticide training.
[FIGURE 13-10 OMITTED]
Federal and state agencies require that applicators keep records of pesticide applications. These records include information such as the name of the pesticide and the formulation used, the date and location of the application, and the pest controlled (Figure 13-11). The applicator must also have special pesticide insurance in case of an accident. The turfgrass manager must be aware of all federal and state pesticide laws. Failure to obey these regulations can result in fines and other penalties.
The Pesticide Label
Pesticide manufacturers are required by law to list certain information on the label attached to the pesticide container. Each statement on the label is reviewed and approved by the EPA. The chemical company obtains this information by conducting years of research costing many millions of dollars. To ensure safe and proper use of a pesticide, the turfgrass manager must read, understand, and follow all directions stated on the label (Figure 13-12).
The following information is found on a pesticide label:
1. Name and address of the manufacturer.
2. Trade (product) name of the pesticide. The same chemical may be sold under several different trade names.
3. List of active ingredients. The percentage, common name, and chemical name of all active ingredients (the toxic chemical that kills the pest) must be listed. The common name is the official name of the pesticide accepted by the EPA. The chemical name is the chemical formula of the toxicant.
4. Type of pesticide (insecticide, fungicide, herbicide, etc.).
5. Type of formulation (wettable powder, emulsifiable concentrate, granular, etc.).
6. EPA registration number.
7. Storage and disposal precautions. These precautions follow federal and state regulations.
8. Hazard statements. All precautions that are necessary for the safe use of the pesticide must be stated. Dangers to people and to the environment must also be stated. Typical warnings are "Avoid contact with skin, eyes, and clothing" or "Keep out of lakes, streams, and ponds." Hazard statements include information such as antidotes that will counteract the effects of the poison and protective clothing that should be worn. All pesticide labels must state the appropriate signal word and the warning "Keep out of reach of children" (Figure 13-13).
9. Directions for use. The specific crops and pests for which the pesticide is registered are listed. It is a violation of the law to use the pesticide on crops and pests that are not listed on the label. The directions also explain how to apply the pesticide. Mixing instructions, rates, the type of equipment to use, and proper timing of the application are included in these directions.
10. Net contents.
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[FIGURE 13-12 OMITTED]
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Safety precautions are essential when handling or applying a pesticide. The following is a list of important safety precautions.
* Read the label carefully before opening the container. All directions stated on the label must be followed exactly. It is illegal to use a pesticide in any manner that is inconsistent with the label.
* Avoid contact with the pesticide. This is especially important when mixing a pesticide because the chemical is in a more concentrated form before it is diluted in the spray tank.
* Wear the protective clothing that is indicated on the label. Protective clothing such as elbow-length rubber, vinyl, or plastic gloves; respirator; face shield; goggles; wide-brimmed waterproof hat; chemical-resistant boots; and a long-sleeved protective suit prevent the absorption of pesticide into the body. Wash protective clothes after each use.
* Have clean water and detergent available. Any pesticide that contacts the applicator's skin should be washed off immediately. Change contaminated clothing immediately. Shower thoroughly after applying a pesticide.
* Never eat, smoke, or drink any liquids while handling pesticides.
* Do not use a highly toxic pesticide if a safer one will do the job.
* Do not increase the recommended pesticide rate. Many applicators think that they can achieve better pest control by doubling the application rate. This is a hazardous practice and it does not result in improved control. Do not attempt to save money by decreasing the rate. Lower rates will be less effective than the recommended rate.
* Always mix just enough pesticide to cover the area to be sprayed. Large amounts of leftover spray are difficult to dispose of properly. Small amounts of unused spray can be applied to an untreated area where the pesticide will not contaminate or damage the environment.
* Be as certain as possible that correct weather conditions will occur during and after a pesticide application. Wind can cause drift. A heavy rain may wash away the chemical. The temperature has an effect on some pesticides.
* Rinse out empty containers at least three times. Do not dispose of them carelessly. Be aware of state regulations concerning pesticide container disposal.
* Store pesticides properly. Keep them locked up, away from children and animals. The locked door should be posted with a warning sign that says "DANGER PESTICIDES" (Figure 13-14). Do not store pesticides in a building that houses people or animals. Do not store them near food or animal feed. Herbicides should be kept separate from other pesticides. Always store pesticides in their original containers. The storage building or room should be dry and have ventilation. Most pesticides have a shelf life of at least two years if they are not exposed to freezing or high temperatures and are kept tightly sealed and dry. However, it is best to use up pesticides as soon as possible.
* Clean up any pesticide spills immediately. Absorptive clay, activated charcoal, pet litter, vermiculite, or sawdust can be used to soak up liquid spills. Any major spills should be reported to the appropriate authorities immediately.
* Report the location of stored pesticides to the local fire department. Many pesticides can give off poisonous fumes if heated or burned. Fire department personnel will need to wear respirators if a fire occurs. Advance notice will alert the fire department to these potential problems.
* Be sure that all employees who work with pesticides are aware of the necessary safety precautions. The employer has a legal responsibility to train workers in handling pesticides safely.
[FIGURE 13-14 OMITTED]
The vast majority of people who work with pesticides never experience a serious mishap. If the applicator is careful and uses common sense, pesticide accidents are unlikely. However, when a person comes into contact with a pesticide, the following steps should be taken immediately after the exposure occurs:
1. Remove the contaminated clothing.
2. Wash off the pesticide thoroughly with a soap or detergent and plenty of water. A shower is the most effective method of removing a pesticide from the skin. If a shower is not available, drench the exposed area with a hose or under a faucet. The faster the toxic chemical is washed off, the less chance of injury.
3. Telephone a doctor immediately if poisoning has occurred. Read the label to the doctor and follow his or her instructions precisely. Every area has a hospital with a poison control center that specializes in treating poisoning victims. If the local doctor is not knowledgeable about pesticide poisoning or is unavailable, call the nearest poison control center. The telephone numbers of the physician and the poison control center must be posted in a location where they are readily available in case of an emergency. The Chemical Manufacturers Association will also provide emergency information when a pesticide accident occurs. This information can be obtained twenty-four hours a day by calling the toll-free number 800-424-9300.
Do not hesitate to seek medical help if pesticide poisoning is suspected. The symptoms of pesticide poisoning include headache, fatigue, dizziness, restlessness, nervousness, nausea, excessive perspiration, diarrhea, loss of appetite, loss of weight, moodiness, abnormal thirst, fever, increased breathing rate, vomiting, lack of muscle coordination, uncontrollable muscle twitches, pinpoint pupils, convulsions, fainting, blurred vision, inability to breathe, and skin, eye, nose, or throat irritations.
Remember that important first aid information is stated on the pesticide label.
Pesticide Application Equipment
Most pesticides are applied with sprayers, but spreaders are also used. The pesticide application equipment must be properly calibrated, or the application may be ineffective, injurious to the turf, or unsafe. Unfortunately, inaccurate calibration is a common problem. Correct application techniques are essential (Figure 13-15). Sprayers and their calibration are discussed in Appendix B; spreaders are discussed in Appendix C.
[FIGURE 13-15 OMITTED]
1. Pesticides that are absorbed into a plant are called --.
2. An emulsifiable concentrate is a type of pesticide --.
3. Granular pesticides are applied with a --.
4. To keep a wettable powder uniformly dispersed in water, the mixture has to be --.
5. Stickers and spreaders are examples of --.
6. -- is the movement of spray droplets by wind.
7. Pesticides that retain their toxicity for a long time are said to be --.
8. Pesticides enter the body orally, through the skin, or by --.
9. Acute toxicity is a measure of how poisonous a pesticide is in a -- exposure.
10. -- toxicity is the result of repeated exposure to pesticides over time.
11. The lower the [LD.sub.50], the -- poisonous the pesticide.
12. A highly toxic pesticide is identified with a skull and crossbones and the signal words --.
13. Some pesticides disrupt the nervous system by inhibiting the enzyme --.
14. If pesticide poisoning occurs, important first aid information can be found stated on the --.
15. Rinse out empty pesticide containers at least -- times.
16. Report the location of stored pesticides to the local --.
17. What telephone numbers should be posted in case of a pesticide emergency?
18. Discuss how to use pesticides safely.
19. What problems can result if pesticides are used incorrectly?
Table 13-1 Pesticide Application Rates * AMOUNT PER ACRE AI/A (LB) FORMULATION 1 2 4 1G 100 lb 200 lb 400 lb 2G 50 lb 100 lb 200 lb 5G 20 lb 40 lb 80 lb 10G 10 lb 20 lb 40 lb 1EC or FL 1 gal 2 gal 4 gal 2EC or FL 2 qt 1 gal 2 gal 4EC or FL 1 qt 2 qt 1 gal 50WP or SP 2 lb 4 lb 8 lb 75WP or SP 1 lb 5 oz 2 lb 11 oz 5 lb 5 oz 80WP or SP 1 lb 4 oz 2 lb 8 oz 5 lb AMOUNT PER ACRE AI/A (LB) FORMULATION 5 10 1G 500 lb 1,000 lb 2G 250 lb 500 lb 5G 100 lb 200 lb 10G 50 lb 100 lb 1EC or FL 5 gal 10 gal 2EC or FL 2.5 gal 5 gal 4EC or FL 1.25 gal 2.5 gal 50WP or SP 10 lb 20 lb 75WP or SP 6 lb 11 oz 13 lb 5 oz 80WP or SP 6 lb 4 oz 12 lb 8 oz AMOUNT PER 1,000 [FT.sup.2] AI/A (LB) FORMULATION 1 2 4 1G 2 lb 5 oz 4 lb 10 oz 9 lb 3 oz 2G 1 lb 2 oz 2 lb 5 oz 4 lb 10 oz 5G 7 oz 15 oz 1 lb 14 oz 10G 4 oz 8 oz 15 oz 1EC or FL 3 oz 6 oz 12 oz 2EC or FL 1.5 oz 3 oz 6 oz 4EC or FL .75 oz 1.5 oz 3 oz 50WP or SP .7 oz 1.5 oz 3 oz 75WP or SP .5 oz 1 oz 2 oz 80WP or SP .5 oz .9 oz 1.8 oz AMOUNT PER 1,000 [FT.sup.2] AI/A (LB) FORMULATION 5 10 1G 11 lb 8 oz 23 lb 2G 5 lb 13 oz 11 lb 8 oz 5G 2 lb 5 oz 4 lb 0 oz 10G 1 lb 3 oz 2 lb 5 oz 1EC or FL 15 oz 29 oz 2EC or FL 7.3 oz 15 oz 4EC or FL 3.7 oz 7.5 oz 50WP or SP 3.7 oz 7.3 oz 75WP or SP 2.5 oz 4.9 oz 80WP or SP 2.3 oz 4.6 oz * These rates may be stated as pounds of active ingredient (AI) per acre or 1,000 [ft.sup.2]. The number preceding the letter abbreviation of the formulation tells how much active ingredient is in the formulated material. For example, a 2EC or 2FL contains 2 pounds of active ingredient per gallon. A 50WP or 50SP is 50% active ingredient; that is, a 4-pound bag would have 2 pounds of active ingredient. Granular formulations have low concentrations of active ingredient. A 5G material has 5% active ingredient. The table lists the amounts of formulated material that are necessary to apply the correct rate of active ingredient. 100 pounds of a 1G-formulated material has to be applied per acre if the recommended application rate is 1 pound of active ingredient per acre. Table 13-2 Signal Words and Categories of Acute Toxicity CATEGORIES [LD.sub.50] SIGNAL WORD REQUIRED ON ORAL DERMAL CATEGORY LABEL (MG/KG) I DANGER 0-50 0-200 Highly toxic (skull and cross-bones) POISON II WARNING Over 50 Over 200 Moderately toxic to 500 to 2,000 III CAUTION Over 500 Over 2,000 Slightly toxic to 5,000 to 20,000 IV CAUTION Over Over Relatively nontoxic 5,000 20,000 CATEGORIES [LD.sub.50] INHALATION * PROBABLE ORAL LETHAL DOSE CATEGORY (MG/L) FOR 150-LB (68-KG) PERSON I 0-2.0 Few drops to 1 teaspoon Highly toxic II Over 2.0 Over 1 teaspoon to 1 ounce Moderately toxic to 20 III Over 20 Over 1 ounce to 1 pint or 1 Slightly toxic to 200 pound IV Over 200 Over 1 pint or 1 pound Relatively nontoxic * Values depend on exposure time.
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|Author:||Emmons, Robert D.|
|Publication:||Turfgrass Science and Management, 4th ed.|
|Date:||Jan 1, 2008|
|Previous Article:||Chapter 12 Water and irrigation.|
|Next Article:||Chapter 14 Weeds.|