Pesticide Formulations Stephen J. Toth, Jr. Wayne G. Buhler Department of Entomology Department of Horticultural Science North Carolina State University North Carolina State University Photograph from U. S. Department of Agriculture

Pesticide Formulations A pesticide formulation is a mixture of active and inert (inactive) ingredients Some formulations are ready-to-use; others must be further diluted with water, a petroleum- based solvent, or air before they are applied Tim McCabe

Purpose of Formulations Increase pesticide effectiveness in the field (availability to pests, persistence) Improve safety features of pesticide (diminish the hazards to user or environment) Enhance the handling qualities of pesticide (equipment, storage) Tim McCabe

Considerations for Choosing a Pesticide Formulation Do you have the necessary equipment to apply the formulation properly? Can the formulation be applied safely in the area and under the conditions of application? Will the formulation reach the target and stay in place long enough to control the pest? Will the formulation harm the surface on which it is applied?

Types of Pesticide Formulations Liquid Formulations Emulsifiable Concentrates Solutions Liquid Flowables Aerosols Dry Formulations Dusts Baits Granules or Pellets Wettable Powders Soluble Powders Microencapsulated Dry Flowables Fumigants Adjuvants

Emulsifiable Concentrate (EC or E) Contains a liquid active ingredient, solvent and agent to allow formulation to mix with water to form an emulsion Product Diluted North Carolina Pesticide Applicator Training Program

Emulsifiable Concentrate (EC or E) Used: in agriculture, ornamentals, turf and forestry, and for livestock, structural and public health pests Advantages: easy to handle, transport and store; little agitation required; not abrasive; doesn’t clog nozzles; and leaves little residue on treated surfaces Disadvantages: mixing and calibration required; toxic to plants and humans (easily absorbed through the skin); can deteriorate metal and rubber; and is flammable

Solution (S) Contains an active ingredient dissolved in a liquid solvent (water or petroleum-based); either a concentrate (must be further diluted) or ready-to-use formulation Product Diluted North Carolina Pesticide Applicator Training Program

Solution (S) Used: for structural pests, livestock and poultry pests, space sprays, shade tree pests, and mosquito control Advantages: no agitation needed Disadvantages: a limited number of formulations of this type available Dana Downey

Liquid Flowable (F or L) Contains insoluble, finely-ground solid active ingredient mixed with a liquid (and inert ingredient) to form a suspension Product Diluted North Carolina Pesticide Applicator Training Program

Liquid Flowable (F or L) Used: same pest control operations as emulsifiable concentrates Advantages: easy to handle and apply; seldom clogs nozzles Disadvantages: require moderate agitation and may leave a viable residue on surfaces Bill Tarpenning

Aerosol (A) Contains one or more active ingredients and solvent (usually petroleum distillate); packaged in a ready-to-use pressurized container, or applied in a smoke or fog generator Used: space spraying, crack and crevice treatments for structural and household pest control Advantages: convenient; the user can purchase small quantities of pesticide; easily stored; and does not lose activity Disadvantages: limited uses; difficult to confine to target site or pest; and risk of inhalation injury

Dust (D) Ready-to-use dry formulation that contains a low percentage of the active ingredient plus a dry, inert carrier (talc, chalk, clay, ash, etc.); used dry Used: to treat seed, control indoor pests (crack and crevice and spot treatments) and parasites on pets and livestock, and used for pests in home gardens Advantages: usually ready-to-use, no mixing; requires simple equipment; effective in hard-to-reach areas Disadvantages: drifts off-target; residues easily moved off target by air and water (rain); doesn’t stick as well as liquids; uneven distribution; irritates eyes, nose, throat

Bait (B) Contains a small amount of dry active ingredient mixed with food or some other attractant; pests ingest pesticide Product North Carolina Pesticide Applicator Training Program

Bait (B) Used: inside buildings for control of ants, roaches, flies, rodents; outdoors for control of rodents, other mammals, birds, slugs, snails and insects Advantages: ready-to-use with no mixing; little hazard to applicator; even distribution not necessary; controls mobile pests; can be removed when pests not present Disadvantages: can be attractive to children, pets and wildlife; pests may prefer crop to bait; dead pests may cause odor problem or secondary poisoning of wildlife

Granule (G) or Pellet (P) Ready-to-use, dry formulations prepared by applying liquid active ingredient to coarse, absorptive material such as clay; pellets are larger, more uniform in shape Used: granular formulations used for soil pests, larval mosquitoes, aquatic pests, and for aerial application to avoid drift; pellets used as pelleted seed, fumigants Advantages: particles settle quickly (low drift); little hazard to applicator; simple application equipment (e.g., spreaders); slow release of pesticide Disadvantages: do not stick to foliage or surfaces; may need to incorporate in soil; may require moisture to activate pesticide; non-target wildlife may use as feed

Wettable Powder (WP or W) Dry, finely-ground formulation with active ingredient mixed with clay or talc; formulation mixed with water to form a suspension for application Product Diluted North Carolina Pesticide Applicator Training Program

Wettable Powder (WP or W) Used: widely used, commercial applications for most pest problems Advantages: easy to store, transport and handle; less likely than EC formulation to harm plants, animals and surfaces; less skin and eye absorption than EC Disadvantages: inhalation hazard to mixers; requires good agitation, will settle out of solution; abrasive to pumps and nozzles; leaves visible residues on surfaces

Soluble Powder (SP) Similar to wettable powder, but dissolves readily and forms a true solution; few pesticides available in this formulation Advantages: has all of the advantages of the wettable powders; non-abrasive to pumps and nozzles; constant agitation not required Disadvantages: inhalation hazard during mixing

Microencapsulated Pesticide (M) Particles of pesticide active ingredient (liquid or dry) surrounded in a plastic coating; formulated product mixed with water and applied as spray; following application the capsule slowly releases the pesticide Advantages: increased safety to applicator; easy to mix, handle and apply; slow release of pesticide Disadvantages: constant agitation required; bees may pick capsules and take back to their hive

Dry Flowable (DF) Active ingredient is prepared as dry, granular-sized particles; granules mixed with water, where they break into fine particles and form a suspension for application Product Diluted North Carolina Pesticide Applicator Training Program

Dry Flowable (DF) Advantages: more easily measured and mixed than wettable powders; less inhalation hazard to mixers Disadvantages: requires constant agitation to keep the formulation in solution

Fumigant (F) Pesticides that form poisonous gases when applied; formulated as liquids or solids; can be released under pressure, high humidity or water vapor Used: agriculture (soil, greenhouses, bins); structural pest control; regulatory pest control (ports, borders) Advantages: toxic to wide range of pests; can penetrate very small areas; usually requires a single treatment Disadvantages: highly toxic to humans and non-target organisms; requires use of specialized application equipment and protective equipment (respirator); the treatment area must be enclosed or covered

Adjuvant Chemical (inert) added to a pesticide formulation or tank mix to increase the effectiveness or safety Includes wetting agents, emulsifiers, spreaders, stickers, foaming agents, thickeners, safeners, compatibility agents, buffers, and anti-foaming agents North Carolina Pesticide Applicator Training Program

Reference Applying Pesticides Correctly: A Guide for Private and Commercial Applicators. Unit 3: Formulations. pp. 29-37.