CHAPTER 4

Pesticide Formulations

LEARNING OBJECTIVES

After studying this chapter, you should: • Understand what a pesticide formulation is. • Know how to interpret common abbreviations used to describe formulations (e.g., WP, DF, EC, RTU, S, G, ULV). • Know how to identify advantages and disadvantages of common formulation types (e.g., dusts, granules, wettable powders, dry flowables, microencapsulated, aerosols). • Know how to explain the role of adjuvants (e.g., buffers, stickers, spreaders) during pesticide application.

Pesticide chemicals in their “raw” • Other ingredients, such as stabi- or unformulated state are not usually lizers, dyes, and chemicals that suitable for pest control. These concen- improve or enhance pesticidal trated chemicals (active ingredients) activity. may not mix well with water, may be Usually you need to mix a formu- chemically unstable, and may be dif- lated product with water or oil for final ficult to handle and transport. For application. Baits, granules, gels, and these reasons, manufacturers add inert dusts, however, are ready for use without substances such as clays and solvents additional dilution. Manufacturers to improve application effectiveness, package many specialized pesticides, Inert safety, handling, and storage. such as products for households, in ingredients do not possess pesticidal ready-to-use formulations. activity and are added to serve as a A single active ingredient often is carrier for the active ingredient. The sold in several kinds of formulations. mixture of active and inert ingredients Abbreviations are often used to describe is called a pesticide formulation. This the formulation (e.g., WP for wettable formulation may consist of: powders); how the pesticide is used • The pesticide active ingredient (e.g., TC for termiticide concentrate); that controls the target pest. or the characteristics of the formulation (e.g., LO for a low-odor formulation). • The carrier, such as an organic The amount of active ingredient (a.i.) solvent or mineral clay. and the kind of formulation are listed • Surface-active ingredients, such on the product label. For example, an as stickers and spreaders. 80% SP contains 80 percent by weight Pesticide formulations 51 Table 4.1 Abbreviations for Formulations

A = Aerosol M = Microencapsulated AF = Aqueous flowable MTF = Multiple temperature formulation AS = Aqueous solution or aqueous sus- P = Pellets pension PS = Pellets B = Bait RTU = Ready-to-use C = Concentrate S = Solution CM = Concentrate mixture SD = soluble dust CG = Concentrate granules SG = Soluble granule D = Dust SP = Soluble powder or soluble packet DF = Dry flowables ULV = Ultra low volume DS = Soluble dust ULW = Ultra low weight or ultra low wettable E = Emulsifiable concentrate W = Wettable powder EC = Emulsifiable concentrate WDG = Water-dispersible granules F = Flowable (liquid) WP = Wettable powder G = Granules WS = Water soluble GL = Gel WSG = Water-soluble granules L = Liquid (flowable) WSL = Water-soluble liquid LC = Liquid concentrate or low concentrate WSP = Water-soluble powder or water- LV = Low volatile soluble packet

of active ingredient and is a soluble • Can the formulation be applied powder. If it is in a 10-pound bag, it appropriately under the condi- contains 8 pounds of a.i. and 2 pounds tions in the application area? of inert ingredient. Liquid formulations • Will the formulation reach your indicate the amount of a.i. in pounds target and stay in place long per gallon. For example, 4F means enough to control the pest? 4 pounds of the a.i. per gallon in a flowable formulation. Some common • Is the formulation likely to formulation abbreviations are listed in damage the surface to which you Table 4.1. will apply it? If you find that more than one • Could I choose a less hazardous formulation is available for your pest formulation that would still be control situation, you should choose the as effective? best one for the job. Before you make the choice, ask yourself several questions To answer these kinds of questions, about each formulation. For example: you need to know something about the characteristics of different types of for- • Do I have the necessary appli- mulations and the general advantages cation equipment? and disadvantages of each type.

AN OVERVIEW OF THE FORMULATION PROCESS

The ingredients in pesticide products sulfur), while a few are derived from come from many sources. Some, such microbes (e.g., Bacillus thuringiensis). as nicotine, pyrethrum, and rotenone, However, the vast majority of active are extracted from plants. Others ingredients are made in the laboratory. have a mineral origin (e.g., copper, These synthetic active ingredients may 52 CHAPTER 4 have been designed by a chemist or liquid. The solid particles do not dis- discovered through a screening process solve in the liquid, and the mixture examining chemicals generated by must be agitated to keep the particles various industries. evenly distributed. Most suspensions Regardless of their source, pes- will have a cloudy, murky appearance. ticide active ingredients have a range The label directs the user to shake well of solubilities. Some dissolve readily in before using. Such products also form water; others, only in oils. Some active suspensions when mixed with water ingredients may be relatively insoluble in for application as a spray. Explicit label either water or oil. Solubility character- information describes the need for istics and the intended use of the pesticide sufficient agitation to keep the solid generally define which formulations best particles of the product dispersed in the deliver the active ingredient. spray tank. Usually, an active ingredient is combined with appropriate inert Emulsion materials prior to packaging. The brief review of basic chemical terminology An emulsion occurs when one below should prove helpful in under- liquid is dispersed (as droplets) in standing differences among the various another liquid. Each liquid retains its types of formulations. original identity. Some degree of agi- tation generally is required to keep the Solution emulsion from separating. Emulsions A solution results when a substance usually have a milky appearance. The is dissolved in a liquid. The components active ingredient is dissolved in an oil- of a true solution cannot be mechani- based solvent. When the product is cally separated. Once mixed, a true mixed with water, an emulsion (oil in solution does not require agitation to water) is formed. An emulsifying agent keep its various parts from settling. (often called an emulsifier) formulated Solutions are frequently transparent, into product helps prevent the emulsion although if they are dark colored, this from separating. may not be the case. Familiarity with these terms and processes leads to a greater under- Suspension standing and appreciation of the A suspension is a mixture of finely advantages and disadvantages of many divided, solid particles dispersed in a commonly used pesticide formulations.

Liquid formulations

Liquid formulations are generally per gallon. ECs are among the most mixed with water, but in some instances versatile formulations. They are used labels may permit the use of crop oil, against agricultural, ornamental and diesel fuel, kerosene, or some other turf, forestry, structural, food processing, light oil as a carrier. Emulsifiable Concentrates (EC or E) An emulsifiable concentrate for- mulation usually contains a liquid active ingredient, one or more petroleum- d applicators d use only by certifie For retail sale an of and only based solvents (which give EC e direct supervision or persons under th plicatorís d by the certified ap formulations their strong odor), and an for those uses covere tion. agent that allows the formulation to be certifica

ooi mixed with water to form an emulsion. kfhksiusj Most ECs contain between 25 and 75 percent (2 to 8 pounds) active ingredient Pesticide formulations 53 livestock, and public health pests. They Ready-to-use Low-concen- are adaptable to many types of appli- trate Solutions (RTU) cation equipment, from small, portable Low-concentrate formulations are sprayers to hydraulic sprayers, low- ready to use and require no further volume ground sprayers, mist blowers, dilution before application. They and low-volume aircraft sprayers. consist of a small amount of active Advantages: ingredient (often 1 percent or less per unit volume) dissolved in an organic • Relatively easy to handle, solvent. They usually do not stain transport, and store. fabrics or have unpleasant odors. They • Little agitation required—will are especially useful for structural and not settle out or separate when institutional pests and for household equipment is running. use. Major disadvantages of low-con- centrate formulations include limited • Not abrasive. availability and high cost per unit of • Will not plug screens or nozzles. active ingredient. Many organic sol- vents are harmful to foliage, so they • Little visible residue on treated often cannot be used as plant sprays. surfaces. Ultra-low Volume (ULV) Disadvantages: These concentrates may approach • High a.i. concentration makes 100 percent active ingredient. They are it easy to overdose or underdose designed to be used as is or to be diluted through mixing or calibration with only small quantities of a specified errors. carrier and are used at rates of no more • May cause damage to desirable than 1/2 gallon per acre. These special plants (phototoxicity). purpose formulations are used mostly in outdoor applications, such as in • Easily absorbed through skin of agricultural, forestry, ornamental, and humans or animals. mosquito control programs. • Solvents may cause rubber or Advantages: plastic hoses, gaskets, and pump parts and surfaces to dete- • Relatively easy to handle, riorate. transport, and store. • May cause pitting or discolor- • Remain in solution; little agi- ation of painted finishes. tation required. • Flammable—should be used and • Not abrasive to equipment. stored away from heat or open • Will not plug screens and nozzles. flame. • Leave little visible residue on • May be corrosive. treated surfaces. Solutions (S) Disadvantages: Some pesticide active ingredients • Difficult to keep pesticide on dissolve readily in a liquid carrier such target—high drift hazard. as water or a petroleum-based solvent. • Specialized equipment required. When mixed with the carrier, they form a solution that does not settle • Easily absorbed through skin of out or separate. Formulations of these humans or animals. pesticides usually contain the active • Solvents may cause rubber or ingredient, the carrier, and one or plastic hoses, gaskets, and pump more other ingredients. Solutions may parts and surfaces to deteriorate. be used in any type of sprayer, indoors or outdoors. • Calibration and application must 54 CHAPTER 4 be done very carefully because of wear of nozzles and pumps. Flowable the high concentration of active and liquid suspensions settle out in ingredient. their containers. Always shake them thoroughly before pouring and mixing. Invert Emulsions Because flowable and liquid formula- An invert emulsion contains a tions tend to settle, manufacturers water-soluble pesticide dispersed in an package them in containers of 5 gallons oil carrier. Invert emulsions require a or less to make remixing easier. special kind of emulsifier that allows the pesticide to be mixed with a large Aerosols (A) volume of petroleum-based carrier, These formulations contain one or usually fuel oil. Invert emulsions aid more active ingredients and a solvent. in reducing drift. With other formula- Most aerosols contain a low percentage tions, some spray drift results when of active ingredients. There are two water droplets begin to evaporate before types of aerosol formulations—the reaching target surfaces; as a result, the ready-to-use type commonly available in droplets become very small and light. pressurized sealed containers, and those Because oil evaporates more slowly products used in electrical or gasoline- than water, invert emulsion droplets powered aerosol generators that release shrink less; therefore, more pesticide the formulation as a “smoke” or “fog.” reaches the target. The oil helps to reduce runoff and improves rain resis- Ready-to-use Aerosols tance. It also serves as a sticker-spreader These formulations are usually by improving surface coverage and small, self-contained units that release absorption. Because droplets are rela- the pesticide when the nozzle valve tively large and heavy, it is difficult to get is triggered. The pesticide is driven thorough coverage on the undersides of through a fine opening by an inert gas foliage. Invert emulsions are most com- under pressure, creating fine droplets. monly used along rights-of-way where These products are used in greenhouses, drift to susceptible non-target plants or in small areas inside buildings, or in sensitive areas can be a problem. localized outdoor areas. Commercial models, which hold 5 to 10 pounds of Flowables (F)/Liquids (L) pesticide, are usually refillable. A flowable or liquid formulation combines many of the characteristics of Advantages: emulsifiable concentrates and wettable • Ready to use. powders. Manufacturers use these for- mulations when the active ingredient is • Portable. a solid that does not dissolve in either • Easily stored. water or oil. The active ingredient, impregnated on a substance such as • Convenient way to buy a small clay, is ground to a very fine powder. amount of a pesticide. The powder is then suspended in a • Retain potency over fairly long small amount of liquid. The resulting time. liquid product is quite thick. Flowables and liquids share many of the features Disadvantages: of emulsifiable concentrates, and they • Practical for only very limited have similar disadvantages. They uses. require moderate agitation to keep them in suspension and leave visible residues, • Risk of inhalation injury. similar to those of wettable powders. • Hazardous if punctured, over- Flowables/liquids are easy to heated, or used near an open handle and apply. Because they are flame. liquids, they are subject to spilling and splashing. They contain solid par- • Difficult to confine to target site ticles, so they contribute to abrasive or pest. Pesticide formulations 55 Formulations for Smoke or Fog Liquid Baits Generators An increasing number of insec- These aerosol formulations are ticides and rodenticides are being not under pressure. They are used in formulated as liquid baits. Liquid machines that break the liquid formu- rodenticides are mixed with water and lation into a fine mist or fog (aerosol) placed in bait stations designed for these using a rapidly whirling disk or heated products. They have two major benefits. surface. These formulations are used Liquid rodenticides are effective in con- mainly for insect control in structures trolling rodents, especially rats, in areas such as greenhouses and warehouses where they cannot find water. They are and for mosquito and biting fly control also effective in areas of poor sanitation outdoors. where ready availability of food renders traditional baits ineffective. Advantages: Liquid insecticide baits are used • Easy way to fill entire enclosed primarily by the structural pest control space with pesticide. industry for controlling ants and, to a lesser extent, cockroaches. They are Disadvantages: packaged as ready-to-use, sugar-based liquids placed inside bait stations. • Highly specialized use and Liquid insecticide ant baits have a equipment. number of advantages. They are very • Difficult to confine to target site effective against certain species of or pest. sugar-feeding ants. These ants typically accept and transfer liquid baits into the • May require respiratory pro- ant colonies. However, some ants will tection to prevent risk of not feed on liquid baits. Liquid baits inhalation injury. also must be replaced often.

DRY OR SOLID FORMULATIONS

Dry formulations can be divided into nut hulls, or volcanic ash. The size of two types: ready-to-use and concen- individual dust particles varies. trates that must be mixed with water to A few dust formulations are con- be applied as a spray. centrates and contain a high percentage of active ingredients. Mix these with dry inert carriers before applying. Dusts are always used dry and can easily drift to non-target sites. They are widely used as seed treatments and sometimes for agricultural applica- tions. In structures, dust formulations are used in cracks and crevices and for spot treatments to control insects such as cockroaches. Insects ingest poisonous dusts during grooming or absorb the dusts through their outer body covering. Dusts also are used to Dusts (D) control lice, fleas, and other parasites Most dust formulations are ready on pets and livestock. to use and contain a low percentage of Advantages: active ingredients (usually 10 percent or less by weight), plus a very fine, dry • Most are ready to use, with no inert carrier made from talc, chalk, clay, mixing.

56 CHAPTER 4 Tracking Powders Special dusts known as tracking powders are used for rodent and insect monitoring and control. For rodent control, the tracking powder consists of finely ground dust combined with a stomach poison. Rodents walk through the dust, pick it up on their feet and fur, and ingest it when they clean them- selves. Tracking powders are useful when bait acceptance is poor because of an abundant, readily available food supply. Non-toxic powders, such as talc or flour, often are used to monitor Arlene Blessing, Purdue Pesticide Programs and track the activity of rodents in Dust formulations are always used dry. buildings. Baits (B) A bait formulation is an active ingredient mixed with food or another attractive substance. The bait either attracts the pests or is placed where the pests will find it. Pests are killed by eating the bait that contains the pes- ticide. The amount of active ingredient in most bait formulations is quite low, usually less than 5 percent. A bulb duster used for applying dust formulations to cracks, crevices, and voids Baits are used inside buildings in buildings. to control ants, roaches, flies, other insects, and rodent control. Outdoors they sometimes are used to control • Effective where moisture from a snails, slugs, and insects such as ants spray might cause damage. and termites. Their main use is for • Require simple equipment. control of vertebrate pests such as rodents, other mammals, and birds. • Effective in hard-to-reach indoor areas. Advantages: Disadvantages: • Ready to use. • Easily drift off target during • Entire area need not be covered application. because pest goes to bait. • Residue easily moved off target • Control pests that move in and by air movement or water. out of an area. • May irritate eyes, nose, throat, and skin. • Will not stick to surfaces as well as liquids. MOUSEMOUSE BAITBAIT STATIONSTATION 0/)3/.0/)3/. DODO NOTNOT TOUCHTOUCH • Dampness can cause clogging and lumping. • Difficult to get an even distri- Closed EN bution of particles on surfaces. OP

A bait station used in rodent control in the closed and open positions. Bait formulations are placed inside the tamper-resistant station.

Pesticide formulations 57 Disadvantages: • When exposed to high tempera- tures, gels can run and drip. • Can be attractive to children and pets. • May stain porous surfaces. • May kill domestic animals and • Repeated applications can cause non-target wildlife outdoors. an unsightly buildup of bait. • Pest may prefer the crop or Granules (G) other food to the bait. Granular formulations are similar • Dead vertebrate pests may cause to dust formulations except granular odor problem. particles are larger and heavier. The coarse particles are made from mate- • Other animals may be poisoned rials such as clay, corncobs, or walnut as a result of feeding on the poi- shells. The active ingredient either soned pests. • If baits are not removed when the pesticide becomes inef- fective, they may serve as a food supply for the target pest or other pests. Pastes, Gels, and Other Injectable Baits Pastes and gels are mainly used in the pest control industry for ants and cockroaches. Insecticides formulated as pastes and gels are now the primary formulations used in cockroach control. They are designed to be injected or placed as either a bead or dot inside Arlene Blessing, Purdue Pesticide Programs small cracks and crevices of building Granular formulations are larger and elements where insects tend to hide or heavier than dust formulations. travel. Two basic types of tools are used to apply pastes and gels—syringes and coats the outside of the granules or bait guns. The applicator forces the bait is absorbed into them. The amount out of the tip of the device by applying of active ingredient is relatively low, pressure to a plunger or trigger. usually ranging from 1 to 15 percent Advantages: by weight. Granular pesticides are most often • They are odorless, produce no used to apply chemicals to the soil to vapors, have low human toxicity, control weeds, nematodes, and insects and last for long periods. living in the soil, or for absorption into • Applicator exposure is minimal. plants through the roots. Granular formulations are sometimes applied

For r etail sa or le and person use on s unde ly by c for tho r the ertifie se use direct d app cer s cove superv licator • Hidden placements minimize tificat red b ision s by airplane or helicopter to minimize i y o on. the ce f and rtified only appli cator’s human and pet exposure. drift or to penetrate dense vegetation. • Very accurate in their placement Once applied, granules release the and dosage. active ingredient slowly. Some granules require soil moisture to release the active • Easily placed in insect harborage ingredient. Granular formulations also A bait gun used by the for maximum effectiveness. are used to control larval mosquitoes pest control industry to and other aquatic pests. Granules are Disadvantages: treat small cracks and used in agricultural, structural, orna- crevices. • Can become contaminated from mental, turf, aquatic, right-of-way, and exposure to other pesticides and public health (biting insect) pest control cleaning products. operations. 58 CHAPTER 4 Advantages: terms often are used interchangeably. In a pellet formulation, however, all • Ready to use—no mixing. the particles are the same weight and • Drift hazard is low, and particles shape. The uniformity of the particles settle quickly. allows use with precision application equipment. A few fumigants are for- • Little hazard to applicator—no mulated as pellets. However, these spray, little dust. are clearly labeled as fumigants. Do • Weight carries the formulation not confuse them with non-fumigant through foliage to soil or water pellets. target. Wettable Powders • Simple application equipment (WP or W) needed, such as seeders or fer- tilizer spreaders. Wettable powders are dry, finely ground formulations that look like • May break down more slowly dusts. They usually must be mixed with than WPs or ECs because of a water for application as a spray. A slow-release coating. few products, however, may be Disadvantages: applied either as a dust or as a wettable powder—the • Often difficult to calibrate choice is left to the equipment and apply uniformly. applicator. Wettable • Will not stick to foliage or other powders contain 5 uneven surfaces. to 95 percent active ingredient by weight; • May need to be incorporated usually 50 percent or into soil or planting medium. more. The particles • May need moisture to activate do not dissolve in water. pesticide. They settle out quickly unless constantly agitated to • May be hazardous to non-target keep them suspended. Wettable species, especially waterfowl and powders are one of the most widely Arlene Blessing, Purdue Pesticide Programs other birds that mistakenly feed used pesticide formulations. They can on the seedlike granules. be used for most pest problems and in Wettable powders • May not be effective under most types of spray equipment where are dry, finely ground agitation is possible. Wettable powders formulations that look drought conditions because the like dusts. active ingredient is not released have excellent residual activity. Because in sufficient quantity to control of their physical properties, most of the pest. the pesticide remains on the surface of treated porous materials such as con- Pellets (P or PS) crete, plaster, and untreated wood. In Most pellet formulations are very such cases, only the water penetrates similar to granular formulations; the the material. Advantages: • Easy to store, transport, and handle. • Less likely than ECs and other petroleum-based pesticides to cause unwanted harm to treated plants, animals, and surfaces.

Arlene Blessing, Purdue Pesticide Programs

In pellet formulations, all particles are the same weight and shape. Pesticide formulations 59 • Easily measured and mixed. by weight; it usually is more than 50 percent. Soluble powders have all the • Less skin and eye absorption than ECs and other liquid for- advantages of wettable powders and mulations. none of the disadvantages except the inhalation hazard during mixing. Few Disadvantages: pesticides are available in this formu- • Inhalation hazard to applicator lation because few active ingredients are while measuring and mixing the readily soluble in water. concentrated powder. Water-dispersible • Require good and constant agi- Granules (WDG) tation (usually mechanical) in or Dry Flowables (DF) the spray tank and quickly settle out if the agitator is turned off. Water-dispersible granules, also Arlene Blessing, Purdue Pesticide known as dry flowables, are like wet- Programs • Abrasive to many pumps and table powders except instead of being Water-dispersible nozzles, causing them to wear dustlike, they are formulated as small, granule before mixing. out quickly. easily measured granules. Water-dis- • Difficult to mix in very hard, persible granules must be mixed with alkaline water. water to be applied. Once in water, the granules break apart into fine particles • Often clog nozzles and screens. similar to wettable powders. The for- • Residues may be visible on mulation requires constant agitation treated surfaces. to keep them suspended in water. The percentage of active ingredient is high, Soluble Powders often as much as 90 percent by weight. (SP or WSP) Water-dispersible granules share many Soluble powder formulations look of the same advantages and disadvan- like wettable powders. However, when tages of wettable powders except: mixed with water, soluble powders dis- • They are more easily measured solve readily and form a true solution. Arlene Blessing, Purdue Pesticide and mixed. Programs After they are mixed thoroughly, no Water-dispersible additional agitation is necessary. The • Because of low dust, they cause granule after mixing. amount of active ingredient in soluble less inhalation hazard to the powders ranges from 15 to 95 percent applicator during handling.

OTHER FORMULATIONS

Other formulations include chemicals • Highly toxic materials are safer that cannot be clearly classified as liquid for applicators to mix and apply. or as dry/solid pesticide formulations. • Delayed or slow release of the Microencapsulated active ingredient prolongs its effec- Materials tiveness, allowing for fewer and less precisely timed applications. Manufacturers cover liquid or dry pesticide particles in a plastic • The pesticide volatilizes more coating to produce a microencapsu- slowly; less is lost from the appli- lated formulation. Microencapsulated cation site. pesticides are mixed with water and • These formulations often reduce sprayed in the same manner as other injury to plants. sprayable formulations. After spraying, the plastic coating breaks down and In residential, industrial, and slowly releases the active ingredient. institutional applications, microen- Microencapsulated materials have capsulated formulations offer several several advantages: advantages. These include reduced odor, 60 CHAPTER 4 release of small quantities of pesticide (saturate) pet collars, livestock ear tags, over a long time, and greater safety. adhesive tapes, plastic pest strips, and Microencapsulated materials offer other products with pesticides. These fewer hazards to the skin than ordinary pesticides evaporate over time, and formulations. Microencapsulated mate- the vapors provide control of rials, however, pose a special hazard to nearby pests. Some paints bees. Foraging bees may carry micro- and wood finishes have encapsulated materials back to their pesticides incorpo- hives because they are about the same rated into them to kill size as pollen grains. As the capsules insects or retard fungal break down, they release the pesticide, growth. Fertilizers also poisoning the adults and brood. may be impregnated Breakdown of the microencapsu- with pesticides. lated materials to release the pesticide sometimes depends on weather condi- Repellents tions. Under certain conditions, the Various types of insect microencapsulated materials may break repellents are available in down more slowly than expected. This aerosol and lotion formulations. M.J. Weaver, Virginia Tech Pesticide could leave higher residues of pesticide People apply these to their skin or Programs active ingredient in treated areas beyond clothing or to plant foliage to repel normal restricted-entry or harvest biting and nuisance insects. You can mix Adding water-soluble packet to a spray tank. intervals with the potential to injure other types of repellents with water and fieldworkers. For this reason, regula- spray them onto ornamental plants and tions require long restricted-entry agricultural crops to prevent damage intervals for some microencapsulated from deer, dogs, and other animals. formulations. Animal Systemics Water-soluble Packets Systemic pesticides protect animals Water-soluble packets reduce the against fleas and other external blood- mixing and handling hazards of some feeding insects as well as against worms highly toxic pesticides. Manufacturers and other internal parasites. A systemic package precise amounts of wettable animal pesticide is one that is absorbed powder or soluble powder formulations and moves within the animal. These in a special type of plastic bag. When pesticides enter the animal’s tissues you drop these bags into a filled spray after being applied orally or externally. tank, they dissolve and release their Oral applications include food additives contents to mix with the water. There and premeasured capsules and liquids. are no risks of inhaling or contacting External applications involve pour-on the undiluted pesticide as long as you liquids, liquid sprays, and dusts. Most do not open the packets. Once mixed animal systemics are used under the with water, pesticides packaged in supervision of veterinarians. water-soluble packets are no safer than other tank mixtures. Pesticide/Fertilizer Combinations Attractants Pest managers frequently use Attractants include pheromones, insecticides, fungicides, and herbicides sugar and protein hydrolysate syrups, in combination with fertilizers. This yeasts, and rotting meat. Pest managers provides a convenient way of con- use these attractants in sticky traps and trolling pests while fertilizing crops capture bags. Attractants also can be or lawns. Homeowners commonly use combined with pesticides and sprayed these combinations, although the unit onto foliage or other items in the cost of pesticide in these formulations treatment area. is usually high. In commercial applica- tions, dealers or growers custom mix Impregnates pesticides with fertilizers to meet spe- Manufacturers impregnate cific crop requirements. Pesticide formulations 61 Fumigants used in soil, greenhouses, granaries, Fumigants are pes- and grain bins. ticides that form Advantages: poisonous gases Fumigant when appl ied. • Toxic to a wide range of pests. S o m e a c t i v e ingredients are • Can penetrate cracks, crevices, l iqu id s when wood, and tightly packed areas pack aged u nder such as soil or stored grains. high pressure and • Single treatment usually kills change to gases most pests in treated area. when t he y a re released. Other active Disadvantages: ingredients are volatile Fumigants are packaged • The target site must be enclosed in liquid and solid forms. liquids when enclosed in an ordinary Both turn into poisonous container and therefore are not formu- or covered to prevent the gas gases when applied. lated under pressure. Others are solids from escaping. that release gases when applied under • Non-specific—highly toxic to conditions of high humidity or in the humans and all other living presence of water vapor. Fumigants organisms. are used for structural pest control, in food and grain storage facilities, and in • Require the use of specialized regulatory pest control at ports of entry protective equipment, including and at state and national borders. In respirators specifically approved agricultural pest control, fumigants are for use with fumigants.

PESTICIDE MIXTURES

C ombining two or more damage done to crops and soil by heavy pesticides and applying them application equipment. Combinations at the same time is conve- may, however, affect the toxicity and nient and cost effective. Most the physical and chemical properties pesticide manufacturers sell of any of the components of the tank some of their products as mix increase residues, and damage premixes, but often you must or injure the target site, plant, or still combine two or more animal. pesticides at the time of appli- If you mix DANGER—POISON cation. When you combine pesticides with WARNING or mixtures of two or more pes- CAUTION pesticides, treat the ticides and/or fertilizers at mixture as a DANGER—POISON the time of application, you pesticide. You must use the required create a tank mix. A common safety equipment and follow all other tank mix involves combining label restrictions found on the label fungicides with insecticides having the greatest restrictions. as a spray for tree fruit crops. Edward Crow, Maryland Department Incompatibility of Agriculture Another involves combining Incompatibility is a two or more herbicides to increase the Incompatibility is a condition condition that prevents number of weed species controlled. that prevents pesticides from mixing pesticides from mixing Some people mix pesticides with together properly to form a uniform together properly to micronutrients or fertilizers. This solution or suspension. The formation form a uniform solution practice saves money by reducing the of flakes, crystals, or oily clumps, or or suspension. time, labor, and fuel required for mul- severe separation is unacceptable. Such tiple applications. Tank mixes reduce incompatible mixtures clog application equipment wear and decrease labor equipment and limit even distribution costs. They lessen the mechanical of the active ingredient in the spray

62 CHAPTER 4 tank. This prevents good pesticide the compatibility test described in coverage. Chapter 10. The cause of incompatibility may Sometimes tank mixes seem com- be the chemical nature of the mate- patible during testing and after mixing rials you are mixing. Impurities in the in the spray tank, but problems arise spray tank or water also may affect during application. This is known compatibility. Even the order in which as field incompatibility. The tem- you mix pesticides in the spray tank perature of the water in the tank can is important. Sometimes the types of formulations being mixed influence cause this problem. It could also be compatibility. Pesticide formulations due to water impurities. Water pH of the same type are rarely incom- (acidity vs. alkalinity) also may unex- patible with one another because they pectedly change for some unknown usually contain many of the same reason. Sometimes the amount of time inert ingredients and solvents. Always the spray mixture has been in the tank evaluate a tank mixture by performing causes field incompatibility.

ADJUVANTS

Adjuvants are chemicals that do not and promotional literature about their possess pesticidal activity. Adjuvants products. are either premixed in the pesticide Adjuvants are designed to perform formulation or added to the spray tank specific functions, including wetting, to improve mixing or application or to spreading, sticking, reducing evapo- enhance pesticidal performance. They ration, reducing volatilization, buffering, are used extensively in products de- emulsifying, dispersing, reducing spray signed for foliar applications. Adjuvants drift, and reducing foaming. No single can be used to customize the formu- adjuvant can perform all these func- lation to specific needs and compensate tions, but compatible adjuvants often TYPES OF for local conditions. can be combined to perform multiple ADJUVANTS The right adjuvant may reduce functions simultaneously. Surfactants or even eliminate spray application Types of Adjuvants Wetting agents problems, thereby improving overall and spreaders pesticide efficacy. Because adjuvants Much of the confusion sur- Stickers themselves have no pesticidal properties, rounding adjuvants can be attributed they are not registered by the EPA. As to the lack of understanding of adjuvant Extenders a result, there is no set of standards terminology. For example, many people Plant penetrants for composition and quality, although use the terms adjuvant and surfactant some states have modified registration Compatibility interchangeably. These terms can refer agents requirements for these chemicals and to the same product because all surfac- may require labels, technical data sheets, tants are adjuvants. However, not all Buffers or pH and efficacy information. adjuvants are surfactants. modifiers Before using any adjuvant, consult Drift retardants Surfactants the pesticide label. Many registered Defoaming agents pesticide products have very specific Surfactants, also called wetting recommendations on their labels for use agents and spreaders, physically alter Thickeners with one or more adjuvants. Failure to the surface tension of a spray droplet. follow these instructions is as much a For a pesticide to perform its function violation of the product label as inap- properly, a spray droplet must be propriate use of the pesticide. able to wet the foliage and spread out If you have questions about the spe- evenly over a leaf. Surfactants enlarge cific properties of an adjuvant, contact the area of pesticide coverage, thereby the manufacturer before attempting to increasing the pest’s exposure to the use it. Companies that produce adju- chemical. Surfactants are particularly vants can provide labels, technical data important when applying a pesticide to sheets, MSDS, supplemental labeling, waxy or hairy leaves. Without proper Pesticide formulations 63 wetting and spreading, spray droplets have named their products “extenders.” often run off or fail to cover leaf sur- Extenders function like stickers by faces adequately. Too much surfactant, retaining pesticides longer on the target however, can cause excessive runoff and area, slowing evaporation, and inhibiting reduce pesticide efficacy. degradation by sunlight. Surfactants are classified by the way they ionize or split apart into electrically Plant Penetrants charged atoms or molecules These adjuvants have a molecular -ˆ`iÊۈiÜʜvʏi>v called ions. A surfactant configuration that enhances pen- with a negative charge is etration of some pesticides into plants. anionic. One with a positive An adjuvant of this type may increase charge is cationic, and one penetration of a pesticide on one species with no electrical charge is of plant but not another. Enhanced pen- nonionic. Pesticidal activity etration increases the activity of some in the presence of a non- pesticides. ionic surfactant can be quite different from activity in Compatibility Agents the presence of a cationic or 7ˆÌ œÕÌÊÃÕÀv>VÌ>˜Ì anionic surfactant. Selecting Pesticides are commonly combined the wrong surfactant can with liquid fertilizers or other pesticides. reduce the efficacy of a Certain combinations can be physi- pesticide product and cally or chemically incompatible, which injure the target plant. causes clumps and uneven distribution in Anionic surfactants are the tank. Occasionally the incompatible most effective when used mixture plugs the pump and distribution with contact pesticides lines resulting in expensive cleanup (i.e., pesticides that control and repairs. A compatibility agent may the pest by direct contact eliminate these problems. rather than being absorbed Read product label directions 7ˆÌ ÊÃÕÀv>VÌ>˜Ì systemically). Cationic carefully before adding a compatibility surfactants should never be agent to a spray mix. You may wish to Adapted from Penn. State Pesticide Education Manual used as stand-alone surfactants because do a compatibility test in a quart jar to Figure 4.1 they usually are phytotoxic. determine the stability of the mixture. Surfactants increase the Nonionic surfactants, often used After adding the desired pesticides and ability of the pesticide to with systemic pesticides, help pesticide the compatibility adjuvant to the jar, spread evenly over the sprays penetrate plant cuticles. Nonionic surface of a leaf or fruit. shake the mixture and then check for surfactants are compatible with most clumping, separation, thickening, and pesticides, and most EPA-registered heat release. Any one of these signs indi- pesticides that require a surfactant rec- cates an incompatibility problem. ommend a nonionic type. Buffers or pH Modifiers Stickers Most pesticide solutions or suspen- A sticker is an adjuvant that increases the adhesion of solid particles to target sions are stable between pH 5.5 and surfaces. These adjuvants can decrease pH 7.0 (slightly acidic to neutral). Above the amount of pesticide that washes off pH 7.0 (alkaline or basic), the pesticide during irrigation or rain. Stickers also may be subject to degradation. Once a can reduce evaporation of the pesticide, pesticide solution becomes alkaline, the and some slow down the degradation of risk exists that the pesticide degrades. pesticides by sunlight. Many adjuvants Buffers and acidifiers are adjuvants that are formulated as spreader-stickers to acidify and stabilize the water in the make a general-purpose product. spray tank. Buffers must be added to the tank mix water first. The water must be Extenders neutralized or slightly acidified prior Some adjuvant manufacturers to adding pesticides and adjuvants 64 CHAPTER 4 Drift Control Additives “causes better root penetration” Drift is a function of droplet size. unless the manufacturer has Small, fine drops with diameters of supporting evidence to back up 100 microns or less tend to drift away such claims. from targeted areas. Drift control • Make sure the adjuvant has been additives, also known as deposition aids, improve on-target placement of thoroughly tested and proven the pesticide spray by increasing the effective for your intended use. average droplet size. Drift reduction Test questionable products on a can be very important near sensitive limited area before proceeding sites and may well be worth the small with full-scale use. reduction in efficacy that may result • Certain pesticides and appli- from the change in droplet size. cation procedures require Defoaming Agents certain types of adjuvants. Some pesticide formulations Determine the correct type create foam or a frothy “head” in spray and use only an adjuvant of tanks. This is often the result of both that type. For example, do not the type of surfactant used in the for- substitute an anionic surfactant mulation and the type of spray tank when a nonionic surfactant is agitation system. The foam usually can recommended. be reduced or eliminated by adding a • A particular pesticide label may small amount of a defoaming agent. require one or more adjuvants Thickeners for a certain use yet prohibit any As the name suggests, thickeners adjuvant for another use. Read increase the viscosity (thickness) the pesticide label carefully. of spray mixtures. These adjuvants • Using an adjuvant is not always are used to control drift or slow necessary. It is just as important evaporation after the spray has been to know when not to use an deposited on the target area. Slowing evaporation is important when using adjuvant as it is to know when systemic pesticides because they can to use one. penetrate the plant cuticle only as long Spray adjuvants can contribute as they remain in solution. substantially to safe and effective pest How to Choose the Right control. Many spray adjuvants are Adjuvant available, each formulated to solve problems associated with a particular Many factors must be considered type of application. Check pesticide when choosing an adjuvant for use in a and adjuvant labels to make sure adju- pest management program. Following vants are suitable for the site you plan to are some guidelines: spray, the target pest, your equipment, • Use only adjuvants manufactured and, of course, the pesticide you plan and marketed for agricultural or to use. horticultural uses. Do not use Remember, many pesticide industrial products or household products already contain an adjuvant. detergents with pesticides If a pesticide is already formulated because they may interfere with properly for your crop, using an addi- pesticide performance. tional wetting agent, for example, may • Remember, there are no miracle not give better spreading or coverage; adjuvants. It is generally wise to instead, it could increase runoff, reduce be skeptical of such claims as deposit, and even severely damage the “keeps spray equipment clean” or target plants.

Pesticide formulations 65 Summary

A pesticide formulation consists of lation types helps the applicator decide both active and inert ingredients. The which one is best to use in a given pest active ingredient (a.i.) functions as the control situation. pesticide; the inert ingredient includes Adjuvants are added to pesticide the carrier and adjuvants. The active formulations to improve the pesticide’s ingredient includes always listed on the ability to control pests, although the product label. The type of formulation adjuvants themselves do not possess pes- may also be given. Persons handling ticidal activity. For example, surfactant pesticides must become familiar with type adjuvants function as wetting the active ingredients and formulation agents or spreaders that improve pes- types to better understand the nature ticide coverage over an area such as of the products. a leaf surface. The pesticide handler Pesticides are formulated in a should know how and when to use an variety of processes such as being dis- adjuvant. Always read the pesticide solved in a solution or dispersed in a label carefully to determine whether suspension or an emulsion. Many liquid adding an adjuvant is recommended for and dry formulations are available, including emulsifiable concentrates use with the pesticide product. (EC), solutions (S), flowables (F), dusts In summary, the pesticide user (D), baits (B), and soluble powders (SP), must consider several factors when to mention a few. Other formulations selecting a pesticide formulation, such are available that cannot be clearly as the risks associated with the formu- classified as either liquid or dry/solid lation type, the practicality of using the pesticide formulations. These products, formulation on the target site or pest, such as microencapsulated materials and whether it will provide effective and water-soluble packets, have special control. Having a basic understanding properties that make them preferable of formulation types before using pesti- for certain pest control situations. cides helps the user avoid mistakes and Understanding the relative advantages accidents in choosing, mixing, loading, and disadvantages of the various formu- and applying the product.

66 CHAPTER 4