Pesticide Applicator Glossary
45 essential terms for the certification exam
Last updated: March 2026
Active Ingredient (AI)
The chemical component of a pesticide product that controls or kills the target pest. Listed on the pesticide label as a percentage of total formulation.
Adjuvant
A substance added to a pesticide formulation to improve its effectiveness, spreading, sticking, or other properties. Examples include surfactants and stickers.
Adsorption
The binding of pesticide molecules to soil particles. Affects how pesticides move through soil and their availability to plants and organisms.
Buffer Zone
A designated area around sensitive sites (water bodies, schools, endangered species habitat) where pesticide application is restricted or prohibited.
Calibration
The process of adjusting application equipment to deliver the correct amount of pesticide per unit area. Ensures accurate application rates.
CAUTION
Signal word indicating a pesticide in toxicity Category III (slightly toxic) or Category IV (practically non-toxic). The least hazardous signal word.
Cholinesterase
An enzyme in the nervous system that breaks down acetylcholine. Organophosphate and carbamate pesticides inhibit cholinesterase, causing nervous system effects.
Commercial Applicator
A person who uses or supervises the use of restricted-use pesticides on property other than their own, or for hire. Requires certification.
DANGER
Signal word for pesticides in toxicity Category I (highly toxic). May include "DANGER-POISON" with skull and crossbones for oral, dermal, or inhalation hazards.
Decontamination
The process of removing pesticide residues from skin, clothing, equipment, or surfaces. Includes triple-rinsing containers and washing exposed skin.
Dermal Exposure
Pesticide entry through the skin. The most common route of exposure for pesticide applicators. Absorption varies by body part and chemical.
Drift
The unintended movement of pesticide spray, vapor, or dust away from the target application site. Affected by wind speed, droplet size, and equipment.
EC (Emulsifiable Concentrate)
A liquid pesticide formulation that mixes with water to form an emulsion. Contains the active ingredient, solvent, and emulsifier.
EPA (Environmental Protection Agency)
The US federal agency responsible for registering pesticides, enforcing FIFRA, setting tolerances, and protecting human health and the environment.
FIFRA
Federal Insecticide, Fungicide, and Rodenticide Act. The primary federal law governing pesticide registration, labeling, distribution, sale, and use in the United States.
Formulation
The physical form in which a pesticide is prepared for use. Common types include EC, WP, WDG, G (granular), and SC (suspension concentrate).
GPA (Gallons Per Acre)
A measure of spray volume applied per acre. Used in calibration calculations. GPA = (GPM x 5940) / (speed in MPH x nozzle spacing in inches).
Groundwater
Water found underground in saturated zones. Pesticide contamination of groundwater is a major environmental concern, especially with soluble chemicals.
Half-life
The time required for half of a pesticide to break down in the environment. Shorter half-lives indicate faster degradation and lower persistence.
Inert Ingredient
Any ingredient in a pesticide product that is not the active ingredient. May include solvents, carriers, surfactants, and other substances.
IPM (Integrated Pest Management)
A systematic approach to pest control that uses monitoring, identification, action thresholds, and a combination of biological, cultural, mechanical, and chemical controls. Chemical control is the last resort.
LC50
Lethal Concentration 50%. The concentration of a pesticide in air or water that kills 50% of test animals in a specified time. Used for inhalation and aquatic toxicity.
LD50
Lethal Dose 50%. The amount of a pesticide that kills 50% of test animals when administered as a single dose. Lower LD50 = more toxic. Measured in mg/kg body weight.
Mode of Action
The biochemical process by which a pesticide controls or kills a pest. Understanding mode of action is critical for resistance management.
MSDS/SDS
Material Safety Data Sheet / Safety Data Sheet. Required document providing detailed information about a chemical product including hazards, handling, first aid, and disposal.
Nozzle
The component of spray equipment that controls droplet size, spray pattern, and flow rate. Types include flat fan, hollow cone, full cone, and flood nozzles.
Organophosphate
A class of insecticides that inhibit cholinesterase enzymes. Highly toxic to insects and potentially to humans. Examples: malathion, diazinon, chlorpyrifos.
Persistence
How long a pesticide remains active in the environment. Highly persistent pesticides may accumulate in soil, water, or organisms over time.
Phytotoxicity
Damage or injury caused by a chemical to plants. Can result from applying the wrong pesticide, wrong rate, or under unfavorable conditions.
PPE (Personal Protective Equipment)
Clothing and equipment worn to reduce exposure to pesticides. Includes chemical-resistant gloves, coveralls, eye protection, and respirators as specified on the label.
Preharvest Interval (PHI)
The minimum number of days between the last pesticide application and crop harvest. Specified on the label to ensure food safety.
Private Applicator
A person who uses or supervises the use of restricted-use pesticides on property they own or rent for agricultural production.
REI (Restricted Entry Interval)
The time period after a pesticide application during which entry into the treated area is restricted. Workers must be notified of REI. Set by WPS.
Resistance
The ability of a pest population to withstand pesticide doses that previously controlled them. Develops through natural selection when the same pesticide is used repeatedly.
Restricted-Use Pesticide (RUP)
A pesticide classified by EPA as having the potential to cause unreasonable adverse effects. Can only be purchased and applied by certified applicators.
Signal Word
A word on a pesticide label indicating the relative acute toxicity: DANGER (Category I, most toxic), WARNING (Category II), or CAUTION (Categories III-IV, least toxic).
SLUDGE
Mnemonic for symptoms of organophosphate/carbamate poisoning: Salivation, Lacrimation (tears), Urination, Defecation, Gastrointestinal distress, Emesis (vomiting).
Surfactant
A substance that reduces surface tension of spray droplets, improving coverage and absorption. Also called a wetting agent or spreader.
Tolerance
The maximum legally allowed amount of pesticide residue on food. Set by EPA based on risk assessment and dietary exposure studies.
Toxicity Category
EPA classification system (I-IV) based on acute toxicity. Category I is most toxic (DANGER/DANGER-POISON), Category IV is least toxic (CAUTION).
Triple Rinse
Required procedure for disposing of pesticide containers: fill container 1/4 with water, cap and shake, pour rinse into spray tank. Repeat three times.
WARNING
Signal word for pesticides in toxicity Category II (moderately toxic). Intermediate hazard between DANGER and CAUTION.
WDG (Water Dispersible Granule)
A dry pesticide formulation that disperses in water. Also called dry flowables. Less dusty than wettable powders.
WP (Wettable Powder)
A dry pesticide formulation mixed with water for spraying. Requires agitation to keep particles suspended. Can be abrasive to equipment.
WPS (Worker Protection Standard)
EPA regulation (40 CFR Part 170) designed to protect agricultural workers and pesticide handlers. Requires training, notification, PPE, decontamination supplies, and emergency assistance.