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Many of the terms below, like individual stewardship practices, do not stand alone but together provide a framework of thinking about stewardship as a crucial component of pesticide use and pest management. Other terms below, though not directly related to stewardship, will help develop a common language regarding agricultural practices, pesticides, and key government regulations. (Photographs Courtesy Of USDA-NRCS. Initial Consolidated Terminology List Courtesy of Syngenta Crop Protection.)

More agricultural terminology resources

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Abrasive – Capable of wearing away or grinding down another object. Some formulations, such as wettable powders, wear out spray nozzles more quickly, necessitating more frequent calibration to ensure that rates are not exceeded.

Absorbed Dose – In exposure assessment, the amount of a substance that penetrates an exposed organism’s absorption barriers (skin, lung tissue, gastrointestinal tract wall, etc.) through physical or biological processes. The term is synonymous with internal dose.

Absorption – The uptake of pesticides into plants and animals. Absorption of pesticides by target and nontarget organisms is influenced by environmental conditions and by the chemical and physical properties of the pesticide and the soil. Once absorbed by plants, pesticides may be broken down or they may remain in the plant until tissue decay or harvest.

Absorption Barrier – Any of the exchange sites of the body that permit uptake of various substances at different rates (e.g., skin, lung tissue, gastrointestinal tract wall, etc.)

Acceptable Daily Intake (ADI) – See Reference Dose.

Acid Deposition – A complex chemical and atmospheric phenomenon that occurs when emissions of sulfur and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere, often far from the original sources, and then deposited on earth in either wet or dry form. The wet forms, popularly called “acid rain,” can fall to earth as rain, snow, or fog. The dry forms are acidic gases or particulates.

Acid Equivalent (a.e.) – The theoretical yield of parent acid from the active ingredient of a herbicide that has been formulated as a derivative of an acid. Rates of phenoxy herbicides, for example, are expressed in terms of acid equivalent.

Action Levels – (1) Regulatory levels recommended by EPA for enforcement by FDA and USDA when pesticide residues occur in food or feed commodities for reasons other than the direct application of the pesticide. As opposed to “tolerances” which are established for residues occurring as a direct result of proper usage, action levels are set for inadvertent residues resulting from previous legal use or accidental contamination. (2) In the Superfund program, the existence of a contaminant concentration in the environment high enough to warrant action or trigger a response under SARA and the National Oil and Hazardous Substances Contingency Plan.

Activated Carbon/Activated Charcoal – A highly adsorbent form of carbon used to remove odors and toxic substances from liquid or gaseous emissions. In waste treatment, it is used to remove dissolved organic matter from waste drinking water. In drinking water treatment plants, it is used to remove taste and odor as well as various contaminants.

Active Ingredient (a.i.) – The active chemical(s) in a pesticide formulation.

Acute Toxicity – A measure of the quantity of a chemical, as a single dosage or concentration, required to cause injury or illness of test animals.

Adjuvant – Chemical added to a pesticide formulation or to the spray tank to increase its effectiveness, safety, or application characteristics.

Adsorption – A process that binds pesticides to soil particles, often because of the attraction between the chemical and soil particles. Positively charged pesticide molecules, for example, are attracted to and can bind to negatively charged clay particles. Soils high in organic matter or clay are more adsorptive than coarse, sandy soils, in part because a clay or organic soil has more particle surface area, or more sites onto which pesticides can bind. Wet soils tend to adsorb less pesticide than dry soils because water molecules compete with the pesticide for the binding sites. Some pesticides such as paraquat and glyphosate bind very tightly, while others bind only weakly and are readily desorbed or released back into the soil solution. Some pesticide labels recommend higher application rates when the chemical is applied to adsorptive soils, because of reduced availability. However, injury can result when a pesticide used for one crop is later released from the soil particles in amounts great enough to cause injury to a sensitive rotational crop. Adsorption is particularly important because it influences whether other processes are able to affect pesticides; for example, soil microorganisms cannot degrade pesticides while they are adsorbed.

Adulterated – (1) Any pesticide whose strength or purity falls below the quality stated on its label. (2) A food, feed, or product that contains illegal pesticide residues.

Adverse Effect – An unexpected adverse condition (such as an unreasonable health effect or unexpected damage to nontarget crops or aquatic/terrestrial organisms) or a new finding in the product chemistry and manufacture of the technical material, which was not previously identified by the registrant. An adverse effect report must be submitted to the EPA by the registrant each time an adverse effect is found.

Aerated Lagoon – A holding and/or treatment pond that speeds up the natural process of biological decomposition of organic waste by stimulating the growth and activity of bacteria that degrade organic waste.

Aerial Application – Pesticide treatment applied with the use of an airplane or helicopter.

A-Horizon – Surface and subsurface with most of the organic matter, microbial and chemical breakdown reactions, and plant roots; varies in depth depending on the geological origins and degree of erosion.

Air Pollutants – Substances in the air that interfere with human health or welfare, or produce other harmful environmental effects; common categories are solids, sulfur compounds, volatile organic chemicals, particulate matter, nitrogen compounds, oxygen compounds, halogen compounds, radioactive compound, and odors.

Alkaline – The opposite of acidic; having a pH greater than 7. Some pesticides are adversely affected in alkaline spray solutions or carryover longer in high pH soils.

Allelopathy – The adverse effect on the growth of plants or microorganisms caused by the action of chemicals produced by other living or decaying plants.

Allergic Effects – Harmful effects, such as skin rash or asthma, that some people develop in reaction to pesticides but that do not cause the same reaction in most other people.

Annual – A plant that completes its life cycle from seed in less than one year.

Antidote (Protectant, Safener) – (1) A chemical added to a pesticide (usually a herbicide) or applied to the crop (usually the seed), to prevent or reduce the harmful effects of a pesticide on a crop. (2) An antidote is also a substance used as a medical treatment to counteract poisoning.

Aquifer, Unconfined – An aquifer containing water that is not under pressure; the water level in the associated well is the same as the water table outside the well. Conversely, confined aquifers are under pressure.

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Bacillus thuringiensis (Bt) – A naturally occurring bacterial disease of insects. Insecticides have been manufactured that contain this bacteria as the active ingredient. Bacillus thuringiensis insecticides are most commonly used against certain leaf and needle-feeding caterpillars. Recently, strains of the bacteria have been produced that affect certain fly larvae, such as mosquitoes, and larvae of leaf beetles. Bacillus thuringiensis is considered safe to humans and non-target species, such as wildlife. Some formulations can be used on essentially all food crops.

Back-Siphoning – The movement of liquid pesticide mixture back through the filling hose and into the water source.

Bacteria (Singular – bacterium) – Microscopic living organisms that can aid in pollution control by metabolizing organic matter in sewage, spill sites, or other contaminated areas. However, there are also bacteria in soil, water or air that can cause human, animal and plant health problems.

Band Application – An application of a pesticide to a continuous narrow strip, usually over, along, or in a crop row, rather than broadcast over the entire field area. Banding reduces the pesticide load on the environment. However, under some circumstances, such as coincidence of ammonia injection furrows and pesticide bands, banding may increase movement of the pesticide through the soil. Also, the additional cultivation which is often needed for weed control between the bands can make herbicide banding unacceptable in areas where cultivation is being avoided to reduce erosion.

Basal Treatment – A pesticide application to the stems or trunks of woody plants at and just above the ground.

Bed – A narrow, flat-topped ridge on which crops are grown, with a furrow on each side for irrigation or drainage of excess water. The bed may be rebuilt during the season as it washes away.

Best Management Practices (BMPs) – Soil, nutrient, and pesticide conservation practices that also provide water quality benefits. They include numerous practices, such as cover crops, green manure crops, and strip-cropping to control erosion, soil testing and timing of chemical applications to prevent the loss of nutrients and pesticides, use of adjuvants to maximize pesticide effectiveness at lowest rates, and careful selection of application methods such as banding to reduce rates.

B-Horizon – Subsoil where leached substances are broken down very slowly and are thus more likely to reach groundwater.

Biennial – A plant that completes its life cycle after an overwintering period which is necessary to initiate the flowering response.

Bioassay – Use of living organisms to determine the presence of a pesticide.

Bioavailability – Degree of ability to be absorbed and ready to interact in organism metabolism.

Bioconcentration – The accumulation of a chemical in tissues of a fish or other organism to levels greater than in the surrounding medium.

Biodegradable – Capable of decomposing under natural conditions.

Biodiversity – Refers to the variety and variability among living organisms and the ecological complexes in which they occur. These items can be organized at many levels, ranging from complete ecosystems to the biochemical structures that are the molecular basis of heredity. Thus, the term encompasses different ecosystems, species, and genes.

Biological Carrying Capacity – The maximum number of animals of a given population that an environment can sustain.

Biological Control/Biocontrol – Man’s use of a specially chosen predator, parasite, or disease to attack a harmful insect, plant pathogen, or weed.

Biological Magnification – Refers to the process whereby certain substances such as pesticides or heavy metals move up the food chain, work their way into rivers or lakes, and are eaten by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. The substances become concentrated in tissues or internal organs as they move up the chain.

Biological/Biochemical Oxygen Demand (BOD) – An indirect measure of the concentration of biologically degradable material present in organic wastes. It usually reflects the amount of oxygen consumed in five days by biological processes breaking down organic waste. The greater the BOD, the greater the degree of pollution.

Bioremediation – Use of living organisms to clean up oil spills or remove other pollutants from soil, water, or wastewater; use of organisms such as non-harmful insects to remove agricultural pests or counteract diseases of trees, plants, and garden soil.

Biotechnology – Techniques that use living organisms or parts of organisms to 1) produce a variety of products (from medicines to industrial enzymes) to improve plants or animals, 2) develop microorganisms to remove toxins from water or soil, or 3) act as pesticides.

Bloom – A proliferation of algae and/or higher aquatic plants in a body of water; often related to pollution, especially when pollutants accelerate growth.

Breakdown of Pesticides – The degradation of pesticides, usually beneficial. Pesticide-destroying reactions change most pesticide residues in the environment to nontoxic or harmless compounds. However, degradation is detrimental when a pesticide is destroyed before the target pest has been controlled. See Chemical Breakdown, Microbial Breakdown, and Photodecomposition.

Broadcast Application – An application of a pesticide uniformly to soil or plants; the term foliar application is usually preferred when insecticides or fungicides are applied to plants.

Broadleaf Weeds – In general, dicotyledonous weeds with net-veined leaves and terminal or axillary meristems.

Buffer Strips – Areas or strips of land maintained in permanent vegetation, designed to intercept pollutants and erosion. Placed around fields, they can enhance wildlife habitat, improve water quality, and enrich aesthetics on farmlands. Various types of buffers include contour buffer strips, filter strips, riparian forest buffers, field borders, windbreaks/shelterbelts, hedgerows, grassed waterways, and alley cropping.

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Carcinogen – A substance or agent capable of producing cancer in animals.

Carrier – A gas, liquid, or solid substance used to dilute or suspend a pesticide during its application.

Carryover – When a pesticide remains in the soil in sufficient quantity to detrimentally affect the following crop(s). There is more potential for carryover in soils high in clay, organic matter, CEC, and pH (high pH reduces chemical and microbial breakdown while increasing availability of some pesticides), and less potential in soils high in microbial and chemical activity (which are favored by a warm, moist, well-aerated, fertile soil with a medium soil pH). Certain pesticide characteristics (low water solubility, strong adsorption, and low susceptibility to microbial or chemical degradation) increase potential for carryover. Carryover potential can be reduced by uniformly applying the lowest recommended rate, accurate acreage determination and chemical measurement, and proper sprayer calibration. Banding of pesticides, early-season application, tillage and cultivation, tank mixtures to reduce the rate of the persistent partner, and selection of a tolerant rotational crop or variety help minimize carryover problems.

Chemical Breakdown – The degradation of pesticides by processes that do not involve living organisms. Temperature, moisture, pH and adsorption, in addition to the chemical and physical properties of the pesticide, determine which chemical reactions take place and how quickly they occur. One of the most common pesticide degradation reactions is hydrolysis, a breakdown process in which the pesticide reacts with water in the spray mix or soil. Many organophosphate and carbamate insecticides are particularly susceptible to hydrolysis under alkaline conditions. Some are actually broken down within a matter of hours when mixed with alkaline water. Product labels may warn against mixing a pesticide with certain fertilizers, other pesticides or water with specific characteristics. Following these precautions can help prevent pesticide degradation and potential incompatibility problems in the spray tank. In some situations, buffers or other additives may be available to modify spray mix conditions and prevent or reduce degradation. Pesticide degradation and possible corrosion of application equipment can be avoided by not allowing a spray mix to remain in a tank for a long period of time.

Chemical Name – The systematic name of a chemical compound according to specific rules of nomenclature. The accepted chemical name is usually the name used in Chemical Abstracts.

Chemical-Resistant – Able to prevent movement of the pesticide through the material during the period of use.

Chemigation – The application of pesticides through irrigation water. The chemigation unit must be calibrated with each use to ensure accurate application. Use a secondary containment structure made of impermeable material where pesticides are stored near the irrigation well when chemigation is practiced, in case of a leak or spill. Minimize runoff and leaching by adjusting amounts and timing based on soil moisture and crop needs to maintain vigorous growth, avoiding movement beyond root zone.

Chemnet – Mutual aid network of chemical shippers and contractors that assigns a contracted emergency response company to provide technical support if a representative of the firm whose chemicals are involved in an incident is not readily available.

Chemtrec – The industry-sponsored Chemical Transportation Emergency Center; provides information and/or emergency assistance to emergency responders.

Chlorosis – Loss of green color (chlorophyll) in foliage, resulting in yellowing of the plant.

Chronic Exposure – Multiple exposures occurring over an extended period of time or over a significant fraction of an animal’s or human’s lifetime (usually seven years to a lifetime).

Chronic Toxicity – A measure of the quantity of a chemical required to cause injury or illness of test animals, after lifetime exposure.

Clean Water Act – The 1977 Clean Water Act established the basic structure for regulating discharges of pollutants into the waters of the United States. It gave EPA the authority to implement pollution control programs such as setting wastewater standards for industry, made it unlawful to discharge any pollutant from a point source into navigable waters (unless a permit was obtained under its provisions), funded the construction of sewage treatment plants and recognized the need for planning to address the critical problems posed by nonpoint source pollution.

Code of Federal Regulations (CFR) – Document that codifies all rules of the executive departments and agencies of the federal government. It is divided into fifty volumes, known as titles. Title 40 of the CFR (referenced as 40 CFR) lists all environmental regulations.

Collecting Pad or Tray – A safety system designed to contain and recover spills, rinsates, leaks, and other pesticide-containing substances.

Common Name – A non-Latin name for a plant species, or a simple (not Chemical Abstracts) name used to identify the active ingredient of a pesticide.

Community Water System (CWS) – A public water system which serves at least 15 service connections used by year-round residents, or regularly serves at least 25 year-round residents. See Non-Community Water System.

Companion Crop/Nurse Crop – A crop (commonly a cereal) grown with another crop (commonly a small-seeded legume) in order to secure a return from the land in the first year of a new seeding of the slow-growing legume. The companion crop also reduces the potential for erosion during the establishment of the legume.

Composting – The controlled biological decomposition of organic material in the presence of air to form a humus-like material. Controlled methods of composting include mechanical mixing and aerating, ventilating the materials by dropping them through a vertical series of aerated chambers, or placing the compost in piles out in the open air and mixing or turning it periodically.

Concentrate – Applied in reduced water volume compared to what is normal for that crop/size/density. Concentrate sprays are often applied in orchards. Also see Dilute.

Concentrated Flow – Runoff that accumulates or converges into well-defined channels.

concentrated flow

Concentrated flow

Confidential Business Information (CBI) – Material that contains trade secrets or commercial or financial information that has been claimed as confidential by its source (e.g., a pesticide or new chemical formulation registrant). EPA has special procedures for handling such information.

Confidential Statement of Formula (CSF) – A list of the ingredients in a new pesticide or chemical formulation. The list is submitted at the time for application for registration or change in formulation.

Conservation – The use, protection, renewing, and improvement of natural resources according to principles that will ensure their highest economic or social benefits.

Contact Herbicide – A herbicide that kills primarily the plant tissue to which it is applied. Such a herbicide will kill seedlings or young plants, but established perennial plants generally recover because below-ground parts are not injured.

Contour Buffer Strips – Series of strips of grass or legumes placed across the slope on a contour, which help trap sediment and nutrients. This is similar to strip-cropping, but with narrower grass or legume strips. The alternating strips of grass or other permanent vegetation slow runoff flow, trap sediment from the crop strips above, and increase water infiltration. Because the buffer strip is established on the contour, runoff flows evenly across the entire surface of the grass strip, reducing sheet and rill erosion.

Contour Furrows – Furrows plowed nearly level around the hill – at right angles to the slope. Crop row ridges subsequently built by tilling and/or planting on the contour create hundreds of small dams. These ridges or dams slow water flow and increase infiltration which reduces erosion.

Contour Strip-Cropping – Crop rotation and contouring combined in equal-width strips of row crop (typically corn or soybeans) planted on the contour and alternated with strips of oats, grass, or legumes. Not more than half a field can be planted to row crops. Oats, grass, or legume slows runoff, increases infiltration, traps sediment and provides surface cover. Ridges formed by contoured rows slow water flow thus reducing erosion. Rotating the strips from corn to legumes allows nutrient-needy crops to benefit from the nitrogen added to the soil by legumes.

Council for Agricultural Science and Technology – A nonprofit organization composed of scientific societies and many individual, student, company, nonprofit, and associate society members, which assembles, interprets, and communicates science-based information regionally, nationally, and internationally on food, fiber, agricultural, natural resource, and related societal and environmental issues, for various stakeholders-legislators, regulators, policy makers, the media, the private sector, and the public.

Cover Crop– A crop grown between crops or between seasons, which is not necessarily harvested but is grown to cover the soil and thus reduce erosion.

Cover Spray – An application after petal fall of fruiting trees, when leaves are fully-expanded.

Critical Area Planting – Planting grass, legumes, trees or shrubs in small, isolated areas of excessive erosion. The vegetation provides surface cover to stop the raindrop splash and slow water flow.

CropLife America – A trade association representing most of the manufacturers of pesticides.

Crop Residue Management – A year-round system beginning with the selection of crops that produces sufficient quantities of residue and may include the use of cover crops after low residue producing crops. CRM includes all field operations that affect residue amounts, orientation and distribution throughout the period requiring protection. Leaving last year’s crop residue on the surface before and during planting operations by reducing tillage provides cover for the soil at a critical time of the year, shielding soil particles from rain and wind until plants can produce a protective canopy. Site-specific residue cover amounts needed are usually expressed in percentage but may also be in pounds. See Tillage, Conservation for tillage systems used with CRM.

Crop Rotation – Changing the crops grown in a field from year to year in a planned sequence. Crop rotations can reduce weed, disease, insect and other pest problems by changing the environment or interrupting their food source; provide alternative sources of soil nitrogen (because alfalfa and other legumes replace some of the nitrogen that corn and other grain crops remove); reduce soil erosion; and reduce risk of water contamination by agricultural chemicals. Crop rotation is a common practice on sloping soils because of its potential for soil saving.

Cultivation – Tillage operations performed for weed control after seeding the crop, using equipment such as a rolling cultivator, conventional row crop cultivator, rotary hoe, or spike-tooth harrow.

Cultural Carrying Capacity – The number of animals that a human or human community will tolerate in a given area.

Cultural Weed Control – Providing the crop with the optimum growing conditions, and utilizing genotype, crop rotation, plant population, row spacing, competitiveness, and other plant-related characteristics so that the crop is able to compete more successfully with weeds.

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Data Call-In – A part of the Office of
Pesticide Programs (OPP) process of developing key required test data, especially on the long-term, chronic effects of existing pesticides, in advance of scheduled Registration Standard reviews. Data Call-In from manufacturers is an adjunct of the Registration Standards program intended to expedite re-registration.

Data Compensation – Under US law, companies who are the original submitters of data to support a product registration, are entitled to receive financial compensation for the data when their competitors rely on such data to obtain their own or substantially similar pesticide registrations (e.g. generic registrations, or me-too registrations). For a new active ingredient, FIFRA 3(c)(1)(F) entitles the original data submitter to 10 years exclusive use protection plus 5 years of data compensation. For all other eligible data, 15 years of data compensation is allowed from the date of the submission.

Decontamination – The removal of pesticide from surfaces or organisms that were exposed, so no further harm or damage can occur.

Defoliant – A chemical that causes the leaves to abscise from a plant.

Delayed Dormant – An application when a plant, typically a fruiting tree, is still dormant but about to enter the pre-bloom stage.

Dermal Exposure – Contact between a chemical and the skin.

Desiccant – Any substance or mixture of substances used to accelerate the drying of plant tissue.

Detection Limit – The lowest concentration of a chemical that can reliably be distinguished from a zero concentration.

Detention Time – (1) The theoretical calculated time required for a small amount of water to pass through a tank at a given rate of flow. (2) The actual time that a small amount of water is in a settling basin, flocculating basin, or rapid-mix chamber of a water treatment plant. (3) In storage reservoirs, the length of time water will be held before being used.

Development Effects – Adverse effects such as altered growth, structural abnormality, functional deficiency, or death observed in a developing organism.

Dilute – Applied in standard water volume for that crop/size/density. Also see Concentrate.

Directed Application – An application of a fungicide or insecticide to a specific part of the crop; or an application of a herbicide to weeds while contacting no more than the lower part of the stems of row crops. This application is done to improve pest control and, with some herbicides, to limit the potential for crop injury.

Directed Band – An application in a continuous narrow strip while contacting no more than the lower part of the stems of row crops.

Direct Filtration – A method of treating water which consists of the addition of coagulant chemicals, flash mixing, coagulation, minimal flocculation, and filtration. Sedimentation is not used.

Disease Cycle – The successive stages from primary infection through incubation, appearance of symptoms, and production of secondary inoculum, which can start the cycle again.

Disposal – Final placement or destruction of toxic, radioactive, or other wastes; surplus or banned pesticides or other chemicals; polluted soils; and drums containing hazardous materials from removal actions or accidental releases. Disposal may be accomplished through use of approved secure landfills, surface impoundments, land farming, deep-well injection, ocean dumping, or incineration. See Pesticides, Proper Handling.

Dissolved Oxygen (DO) – The oxygen freely available in water, vital to fish and other aquatic life and for the prevention of odors. DO levels are considered a most important indicator of a water body’s ability to support desirable aquatic life. Secondary and advanced waste treatment steps are generally designed to ensure adequate DO in waste-receiving waters.

Dissolved Solids – Disintegrated organic and inorganic material in water. Excessive amounts make water unfit to drink or use in industrial processes.

Diversion – A channel or earthen embankment, much like a terrace, constructed across the land slope to intercept and divert surface runoff from a specific area to an outlet. A diversion is often built at the base of a slope to divert runoff away from bottom lands. A diversion may also be used to divert runoff flows away from a feedlot, or to collect and direct water to a pond.

Dormancy – The state of inhibited seed germination or growth of a plant. Winter annuals, biennials, and perennial plants usually have a period of dormancy during the winter. Dormancy may be genetically or environmentally induced.

Dose-Response – Shifts in toxicological responses of an individual (such as alterations in severity) or populations (such as alterations in incidence) that are related to changes in the dose of any given substance.

Double Cropping – Two crops grown in quick succession, instead of the normal practice of growing one or the other. Most commonly, winter wheat is harvested and immediately followed by a late-seeded soybean variety that requires a slightly shorter growing season than a conventional variety.

Drag-Off – Cultivation (by harrowing) of the hill before the crop (especially potatoes) emerges. Herbicides may be applied after drag-off for control of unemerged weeds.

Drainage, Subsurface – The removal of excess water from the soil profile by means of drain tiles, perforated pipes, or other devices.

Drainage, Surface – The diversion or orderly removal of excess water from the surface of the land by means of improved natural or constructed channels, supplemented when necessary by the sloping and grading of land surfaces to these channels.

Drench Application – A pesticide poured around the base of the tree or on the tree trunk.

Drift – Movement of airborne drops of spray solution, or vapors, from the intended area of application to nontarget species. Generally granules and pellets reduce drift compared to wettable powders and other liquid sprays. Dusts are most susceptible to drift. For liquid sprays, adjust equipment to minimize fine droplets, which are most susceptible to drift. Release pesticide spray as close to the target as possible, in calm (10 mph or less) weather conditions. Windy conditions or air conditions created by a temperature inversion (cold air trapped between the soil surface and warm air above) generally contribute to pesticide drift.

Drinking Water State Revolving Fund – Fund which provides capitalization grants to states to develop drinking water revolving loan funds to help finance system infrastructure improvements, assure source-water protection, enhance operation and management of drinking-water systems, and otherwise promote local water-system compliance and protection of public health.

Drip Application – Slow, monitored release of pesticide through drip irrigation equipment to conserve water.

Dust – A formulation providing excellent coverage of mature crops with dense foliage, because its carrier (talc, clay, finely ground plant parts, etc.) has very small particle sizes. It is highly susceptible to drift.

Dystrophic Lakes – Acidic, shallow bodies of water that contain much humus and/or other organic matter; they contain many plants but few fish. See eutrophic lakes.

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Early Preplant (EPP) – Herbicides applied two weeks or more before planting the crop. Products that can be applied early preplant as well as preplant and preemergence give the grower a wider application window, making adverse weather conditions like rainy weather less likely to hinder or prevent the application. Stewardship is also aided by products that give growers the flexibility to wait instead of spraying prior to adverse weather conditions such as heavy rain.

Ecological Risk Assessment – The application of a formal framework, analytical process, or model to estimate the effects of human action(s) on a natural resource and to interpret the significance of those effects in light of the uncertainties identified in each component of the assessment process. Such analysis includes initial hazard identification, exposure and dose-response assessments, and risk characterization.

Ecosystem – An ecological entity consisting of the biotic community and the nonliving environment functioning together in an interacting system.

Emergence – The breaking through the soil surface by a plant seedling or an elongating shoot.

Emulsifier – Chemical that allows petroleum-based pesticides (EC’s) to mix with water.

Emulsion – A mixture of two or more liquids that are not soluble in one another. One is suspended as small droplets in the other.

Endangered Species – Organisms whose survival as a species has been designated by a Federal Agency to be endangered or threatened.

Endangered Species Act – This 1973 Act provides a program for the conservation of threatened and endangered plants and animals and the habitats in which they are found. The US Fish and Wildlife Service maintains the list of endangered and threatened species. Species include birds, insects, fish, reptiles, mammals, crustaceans, and plants ranging from grasses to trees. Anyone can petition FWS to include a species on this list. The law prohibits any action, administrative or real, that results in a “taking” of a listed species, or adversely affects habitat. Likewise, import, export, interstate, and foreign commerce of listed species are all prohibited. EPA’s decision to register a pesticide is based in part on the risk of adverse effects on endangered species as well as environmental fate (how a pesticide will affect habitat). Under FIFRA, EPA can issue emergency suspensions of certain pesticides to cancel or restrict their use if an endangered species will be adversely affected. EPA, FWS, and USDA are preparing county bulletins that include habitat maps, pesticide use eliminations, and other actions required to protect listed species.

Enrichment – The addition of nutrients (e.g., nitrogen, phosphorus, carbon compounds) from sewage effluent or agricultural runoff to surface water, greatly increasing the growth potential for algae and other aquatic plants.

Environment – The sum total of all biological and physical factors affecting an organism, population, or community.

Environmental Protection Agency – The government agency formed in 1970 and charged with protecting human health and the environment. EPA works to develop and enforce regulations that implement environmental laws enacted by Congress. EPA delegates to states and tribes the responsibility for issuing permits and for monitoring and enforcing compliance. Where national standards are not met, EPA can issue sanctions and take other steps to assist the states and tribes in reaching the desired levels of environmental quality

Epinasty – That state in which more rapid growth on the upper side of a plant organ or part (especially leaf) causes it to bend or curl downward.



Erosion – The detachment and movement of surface soil and rock particles by gravity, wind, water, freezing and thawing, and/or other natural phenomena, which is intensified by land-clearing practices related to farming, residential or industrial development, road building, or logging.

Eutrophication – The slow aging process during which a lake, estuary, or bay evolves into a bog or marsh and eventually disappears. During the later stages of eutrophication the water body is choked by abundant plant life due to higher levels of nutritive compounds such as nitrogen and phosphorus. Human activities can accelerate the process.

Eutrophic Lakes – Shallow, murky bodies of water with concentrations of plant nutrients causing excessive production of algae. See dystrophic lakes.

Exemption – An excuse given by a state (with primacy) to a public water system from a requirement involving a Maximum Contaminant Level (MCL), treatment technique, or both, if the system cannot comply due to compelling economic or other factors, or because the system was in operation before the requirement or MCL was instituted; and the exemption will not create a public health risk. Also called a variance.

Experimental Use Permit (EUP) – A permit granted by EPA that allows a producer to conduct tests of a new pesticide, product and/or use outside the laboratory. The testing is usually done on ten or more acres of land or water surface, as opposed to small research plots.

Eyewash Dispenser – Commercially available system for flushing contaminants out of the eyes.

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Fallow – Cropland left idle, usually for one growing season in dryland areas, during which time either herbicides (chemical fallow) or tillage is used to control weeds and build up moisture reserves for the next crop.

Fall Preplant – Herbicides applied in the fall, prior to planting the crop the following spring. Timing is critical relative to soil freeze-up, to ensure that product does not degrade or move in the environment during the fall or winter months.

farm with a pond

Farm pond

Farm Pond – A water body typically formed by building a dam across an existing gully or low-lying area. Earth for the dam is dug out above the dam with heavy machinery to form a bowl, to supply water for livestock, recreation and wildlife, and to control gully erosion. Generally the ponded area fills with water within a year. An overflow pipe is installed through the dam to control the water level and allow water to spill through the dam without causing erosion.

Federal Insecticide, Fungicide and Rodenticide Act – This 1947 Act is used by the EPA to regulate: 1) the registration of all pesticides used in the United States, 2) the licensing of pesticide applicators, 3) re-registration of all pesticide products, 4) and the storage, transportation, disposal and recall of all pesticide products. FIFRA was amended in 1972, and has subsequently been amended several more times, most recently by the Food Quality Protection Act of 1996.Federal Register – A daily government publication where all federal regulatory actions, including proposed rules, final rules, and notices are published.

Field Border – Strips of perennial vegetation (grass or legumes) established at the outside edges of a field where excessive sheet and rill erosion is occurring. The grass or legume strips replace crop end rows, which would be planted up and down hill and be highly erosive. Field borders are sometimes referred to as picture frames of grass, and are used with contour farming, terrace, buffer strip and contour strip-cropping systems. The grass or legume in the strip protects steep field edges from soil erosion, and provides turning and travel lanes around the field.

Filter Strip – A strip of grass, trees, or shrubs that filters runoff and removes sediment, fertilizer, and pesticides before they reach water bodies or water sources including wells. Strips of grass, trees and/or shrubs slow water flow and cause contaminants like sediment, pesticides, and fertilizers to collect in vegetation. Collected nutrients are used by the vegetation, rather than entering water supplies. Filtered water then enters water bodies.

Finished Water – Water that has passed through all the processes in a water treatment plant and is ready to be delivered to consumers.

Foliar Application – A uniform application of a pesticide to emerged plants. Also see Broadcast Application.

Food and Drug Administration – One of our nation’s oldest consumer protection agencies, charged with monitoring the manufacture, import, transport, storage and sale of about $1 trillion worth of products each year. Foremost, FDA is a public health agency, charged with protecting American consumers by enforcing the Federal Food, Drug, and Cosmetic Act and several related public health laws. To carry out this mandate of consumer protection, FDA has some 1,100 investigators and inspectors who cover the country’s almost 95,000 FDA-regulated businesses. Food (e.g. pesticide residues), cosmetics, medicines, microwave ovens, and food and drugs for pets are among the myriad of products under FDA jurisdiction.

Formulation – A physical mixture of one or more pesticides plus non-pesticide ingredients by a manufacturer for practical use. The formulation may influence effectiveness, selectivity, ease of application, packaging, and cost.

FQPA – The Food Quality Protection Act (FQPA) of 1996, which amended the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food, Drug, and Cosmetic Act (FFDCA). These amendments fundamentally changed the way EPA regulates pesticides. The requirements include a new safety standard for “reasonable certainty of no harm” that must be applied to all pesticides used on foods, and additional criteria which EPA must consider when making decisions on food tolerances and product registrations. Provisions in FQPA consider criteria that are most relevant to aggregate exposure assessment and potential exposure to infants and children. Also see Risk Cup.

Frill Treatment – Placement of a herbicide into a series of overlapping ax cuts made through the bark in a ring around the trunk of a tree.

Fumigant – Pesticide that is a vapor or gas or that forms a vapor or gas when applied and whose pesticidal action occurs in the gaseous state.

Fumigation – A pesticide application in gaseous or volatile liquid form, usually made in an enclosed area or incorporated into the soil.

Fungi – (Singular – fungus) Molds, mildews, yeasts, mushrooms, etc., which lack chlorophyll (are not photosynthetic) and which are usually non-mobile, filamentous, and multicellular. Some grow in soil while others attach themselves to decaying trees and other plants to obtain nutrients. Some are pathogens while others are beneficial, such as those used to stabilize sewage and digest composted waste.

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Generally Recognized as Safe (GRAS) – Designation by the FDA that a chemical or substance (including certain pesticides) added to food is considered safe by experts, and so is exempted from the usual food additive tolerance requirements.

Geographical Information Systems – A computerized database for the capture, storage, analysis, and display of spatial information. Database records are linked to a precise location that can be plotted on a map. As much as two-thirds of all the information residing in government or corporate files have spatial characteristics.

Genetic Engineering – A process of inserting new genetic information into existing cells in order to modify a specific organism for the purpose of changing one of its characteristics.

Germination – The process of initiating growth in seeds, spores, or other plant propagules.

Good Laboratory Practices – Standards established by EPA to assure the quality and integrity of test data submitted to the Agency under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Toxic Substances Control Act (TSCA), including laboratory inspections and data audits to ensure compliance.

grade control in place

Grade control structure

Grade Control Structure – A dam, embankment or other structure built across a drainageway (such as a grassed waterway or existing gully) to reduce water flow and prevent gully erosion. The structure drops water from one stabilized grade to another and prevents gullies from advancing up a slope.

Granule – A formulation which must disintegrate in the presence of moisture (in soil, in the crop whorl, etc.) to release the active ingredient.
Grade Control Structure

Granule – A formulation which must disintegrate in the presence of moisture (in soil, in the crop whorl, etc.) to release the active ingredient.

Grassed Waterway – A natural or constructed drainageway or outlet that is graded and shaped to form a smooth, bowl-shaped channel. This area is seeded to suitable vegetation, often sod-forming grasses. Runoff water that flows down the drainageway disperses across the grass rather than tearing away soil and forming a larger gully. An outlet is often installed at the base of the drainageway to stabilize the waterway and prevent a new gully from forming.

Grass Weeds – In general, monocotyledonous, parallel-veined weeds of the botanical family Gramineae.

Green Manure – A crop that is plowed under for soil improvement.

Groundwater – The water below the soil surface, which fills the pores, voids, fractures, and other spaces in and around rock, gravel, sand and other materials, and moves through water-saturated zones called aquifers.

Groundwater Under the Direct Influence of Surface Water – Any water beneath the surface of the ground with either 1) significant occurrence of insects or other microorganisms, algae, or large-diameter pathogens or 2) significant and relatively rapid shifts in water characteristics such as turbidity, temperature, conductivity, or pH which closely correlate to climatological or surface water conditions. Direct influence is determined for individual sources in accordance with criteria established by a state.

Gully Erosion – Severe erosion in which trenches are cut to a depth greater than 30 centimeters (1 ft). Generally, ditches deep enough to cross with farm equipment are considered gullies.

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Half-Life – The time it takes for half of the active ingredient in a pesticide to become inactive. The half-life varies for a particular pesticide depending on the environmental conditions.

Harmonization – EPA recognizes that there are national differences in tolerances and pesticide registrations. Resolving these differences are a priority for growers and is becoming a priority for the EPA, PMRA and other regulatory authorities. EPA will consider “harmonizing” these trade barriers providing there is a level of protection and safety in the international standards. The regulatory authorities will benefit since compliance and enforcement will be simplified. In addition, harmonization benefits the grower, consumer, and the pesticide industry.

Health Advisory Level (HAL) – A non-regulatory health-based reference level of chemical traces (usually in ppm) in drinking water at which there are no adverse health risks when ingested over various periods of time. Such levels are established for one day, 10 days, long-term and lifetime exposure periods. They contain a wide margin of safety. See Maximum Contaminant Level.
Hill – A high ridge of soil thrown over unemerged crop rows (especially potatoes), to kill emerging weeds before the crop emerges. Herbicides may be applied at hilling for control of unemerged weeds.

Hormone – A growth regulating chemical occurring naturally in plants or animals, which moves from the site of production to the site of action.

Host – A plant that is invaded by a parasite and from which the parasite obtains its nutrients.

Hypoxia/Hypoxic Waters – Waters with dissolved oxygen concentrations of less than 2 ppm, the level generally accepted as the minimum required for most marine life to survive and reproduce.

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Incompatibility, Chemical – Two pesticides which, upon mixing, have an unacceptable chemical reaction resulting in unusual or loss in activity.

Incompatibility, Physical – Two pesticides which, upon mixing, have an unacceptable physical reaction resulting in precipitation, coagulation, etc.

Incorporated – A pesticide application that is mixed into the soil mechanically or by irrigation, to improve control of soil organisms or germinating weeds, or reduce the pesticide’s loss by surface runoff, volatility, and/or photodecomposition. However, this practice may increase the amount of pesticide that leaches through the soil.

Incubation Period – The period of time between the penetration of a host by a pathogen (infection) and the first appearance of symptoms on the host.

Inert Ingredients – Inactive components of a pesticide formulation that are used to dilute the pesticide, make it easier to measure, mix, apply, and store, and/or improve safety and effectiveness. These include solvent or solid diluents, and adjuvants such as emulsifiers, surfactants, wetting agents, spreaders, adhesives, activators, dispersing agents, penetrants, and detergents.

Infection – The establishment of a parasite within a host plant.

Infiltration – The downward entry of water into the earth’s surface. Infiltration usually refers to water movement into a soil or rock surface while the terms hydraulic conductivity, percolation, and permeability usually relate to water movement within a soil or rock layer.

Infiltration Gallery – A sub-surface groundwater collection system, typically shallow in depth, constructed with open-jointed or perforated pipes that discharge collected water into a watertight chamber from which the water is pumped to treatment facilities and into the distribution system. Usually located close to streams or ponds.

In-Furrow Application – Insecticides or fungicides applied in the furrow before closing. The furrow is the opening made in the soil to plant the seed.

Injection – An application made through the trunk of a tree or into the soil. Soil injection is often done with side-dress fertilizer applicators.

In-Line Filtration – Pre-treatment method in which chemicals are mixed by the flowing water; commonly used in pressure filtration installations. Eliminates need for flocculation and sedimentation.

Inoculum – The pathogen or its parts that can cause infection. That portion of individual pathogens that are brought into contact with the host.

Integrated Pest Management (IPM) – An ecosystem-based, multi-disciplinary strategy using biological, chemical, cultural, mechanical, genetic, and educational methods to keep pests below unacceptable economic thresholds. IPM includes pest prevention, regular pest and weather monitoring, habitat manipulation, crop rotation, natural enemies, biological control, pest-resistant varieties, pest attractants and repellents, biopesticides, and synthetic organic pesticides. In its best form, it is a long-term strategy which minimizes any detrimental effects on human health, the environment, and non-target organisms.

Interregional Research Project No. 4 – A federally funded program established in 1963 to conduct the research necessary for obtaining registrations of pesticides needed to grow minor crops. IR-4 works with farmers, agricultural scientists, and extension personnel to conduct research and petition the EPA for tolerances for specific pesticides. The IR-4 program has grown to include biological pest control agents and biochemicals.

Interseeding – Seeding one crop in rows in another.

Inversion – A layer of warm air that prevents the rise of cooling air and traps pollutants beneath it; it can cause an air pollution episode.

Invert – A formulation which forms a water-in-oil emulsion in the spray tank, as opposed to the oil-in-water emulsion formed by Emulsifiable Concentrate formulations. Since the water must be suspended in the oil, much less water is used in the spray tank. The oil droplets are large and evaporate little, greatly reducing the probability of drift.

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Juvenile Hormones – Natural insect chemicals that keep the earlier stages of an insect from changing into the normal adult form.

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  1. Special Local Need (SLN) or 24(c) – A registration issued by a state regulatory agency in conjunction with EPA for use of a pesticide product under FIFRA Section 24(c) for a specific use that is not federally registered. The active ingredient, however, must be federally registered for other uses. The special use is specific to that state for an imminent pest problem, and is usually a minor use application that does not warrant the additional cost of a full federal registration process. The 24C has a full registration status, and the approval is based upon justification for the 24C, satisfactory supporting data, an established tolerance or exemption from tolerance, and determination that appropriate federally registered pesticide products are not sufficiently available. A 24C cannot be issued for new active ingredients, food-use active ingredients without tolerances, or for a canceled registration.
  2. Section 18 – FIFRA legislation includes a Section 18 that describes conditions in which an emergency use exemption is granted for use of a pesticide not yet federally registered, or not yet registered for the specific use. The Section 18 will only be granted by the EPA to a state or a federal agency on a case by case basis and considers hardship to the grower as well as financial loss due to crop destruction. The registrant must show progress towards registration of the use prior to a time-limited tolerance issued by EPA when the exemption is granted. Such actions involve unanticipated and/or severe pest problems where there is not time or interest by a manufacturer to register the product for that use. Registrants cannot apply for emergency exemptions.
  3. 2ee – FIFRA legislation under the 2ee allows “labeling” as long as it is consistent with the registered and approved Section 3 label for the pesticide product. Labels under 2ee are used to provide a convenient tool for the grower and also may enhance the competitive edge of the product. The following are some examples of possible 2ee labels – 1) use directions describing application of a pesticide at a lower rate than that which is on the product label, 2) employing a method of application not prohibited by the labeling, or 3) mixing a pesticide with a fertilizer when such a mixture is not prohibited by the labeling.
  4. Conditional Registration – Under special circumstances, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) permits registration of a pesticide product that is “conditional” upon the submission of additional data. These special circumstances include a finding by the EPA Administrator that a new product or use of an existing pesticide will not significantly increase the risk of unreasonable adverse effects. A product containing a new (previously unregistered) active ingredient may be conditionally registered only if the Administrator finds that such conditional registration is in the public interest, that a reasonable time for conducting the additional studies has not elapsed, and the use of the pesticide for the period of conditional registration will not present an unreasonable risk

Layby – The latest time during the season that the grower can still get into the field to cultivate a row crop. Pesticides may also be applied by ground application at this time (at layby application).

LC50 – The lethal concentration of a chemical that will kill 50% of the test organisms within a designated period. The lower the LC50, the more toxic the compound.

LD50 – The lethal dose of a chemical that will kill 50% of the test organisms within a designated period. The lower the LD50, the more toxic the compound.

Leaching – The downward movement of pesticides in water moving through the soil profile, rather than over the surface (the latter is runoff). Leaching depends, in part, on the pesticide’s chemical and physical properties. For example, a pesticide held strongly to soil particles by adsorption is less likely to leach. Another factor is solubility. A pesticide that dissolves in water can move with water in the soil. The persistence, or longevity, of a pesticide also influences the likelihood of leaching. A pesticide that is rapidly broken down by a degradation process is less likely to leach because it may remain in the soil only a short time. Soil factors that influence leaching include texture and organic matter, in part because of their effect on pesticide adsorption. Soil permeability (how readily water moves through the soil) is also important. The more permeable a soil, the greater potential for pesticide leaching. A sandy soil is much more permeable than a clay. The method and rate of application, the use of tillage systems that modify soil conditions, and the amount and timing of water a treated area receives after application can also influence pesticide leaching. Typically, the closer the time of application to a heavy or sustained rainfall, the greater the likelihood that some pesticide leaching will occur. A certain, small amount of pesticide leaching may be essential for control of a target pest. Too much leaching, however, can lead to reduced pest control, injury of nontarget species and groundwater contamination. Monitoring weather conditions and the amount and timing of irrigation can help minimize pesticide leaching. Careful pesticide selection is important because those pesticides that are not readily adsorbed, not rapidly degraded, and highly water soluble are the most likely to leach. The label may also advise against using the pesticide when certain soil, geologic or climatic conditions are present. Pesticides can leach through the soil to groundwater from storage, mixing, equipment cleaning, disposal areas, and even from normal applications. It is critical to know the geology and the relative depth of the groundwater in your area to prevent contamination by leaching.

Lesion – A localized area of discolored, diseased tissue.

Life cycle – The successive stages in the growth and development of an organism that occur between the appearance and reappearance of the same state (e.g., spore or seed) of the organism.

Lifetime Exposure – Total amount of exposure to a substance that a human would receive in a lifetime (usually assumed to be 70 years).

Limit of Detection (LOD) – The minimum concentration of a substance being analyzed that has a 99 percent probability of being identified.

Lowest Observed Adverse Effect Level (LOAEL) – The lowest level of a stressor that causes statistically and biologically significant differences in test samples as compared to other samples subjected to no stressor.

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Margin of Exposure (MOE) – The ratio of the no observed adverse effect level (NOAEL) to the estimated exposure dose.

Margin of Safety (MOS) – The ratio of the maximum amount of exposure producing no measurable effect in animals (or studied humans) to the actual amount of human exposure in a population.

Maximum Contaminant Level (MCL) – The maximum permissible level of a contaminant in water delivered to any user of a public system. MCL’s are enforceable standards, while HAL’s are not. See Health Advisory Level.

Maximum Contaminant Level Goal (MCLG) – Under the Safe Drinking Water Act, a non-enforceable concentration of a drinking water contaminant, set at the level at which no known or anticipated adverse effects on human health occur and which allows an adequate safety margin. The MCLG is usually the starting point for determining the regulated Maximum Contaminant Level.

Maximum Residue Level (MRL) – Comparable to a U.S. tolerance level, the enforceable limit on food pesticide levels in some countries. Levels are set by the Codex Alimentarius Commission, a United Nations agency managed and funded jointly by the World Health Organization and the Food and Agriculture Organization. See Tolerance.

Mechanical Weed Control – Physically controlling weeds by using implements ranging from the hoe to large field cultivators.

Method Detection Limit (MDL) – See Limit of Detection.

Microbial Breakdown – The degradation of pesticides by fungi, bacteria, and other microorganisms that use pesticides as a food source. Most microbial degradation of pesticides occurs in the soil. Soil conditions such as moisture, temperature, aeration, pH, and the amount of organic matter affect the rate of microbial degradation because of their direct influence on microbial growth and activity. The frequency of pesticide application also is a factor that can influence microbial degradation. Rapid microbial degradation is more likely when the same pesticide is used repeatedly in a field. Repeated applications can actually stimulate the buildup of organisms that are effective in degrading the chemical. As the population of these organisms increases, degradation accelerates and the amount of pesticide available to control the pest is reduced. In extreme cases, accelerated microbial degradation has led to certain products being removed from the marketplace. Microorganisms greatly reduced the effectiveness of these chemicals soon after application. The possibility of very rapid pesticide breakdown is reduced by using pesticides only when necessary and by avoiding repeated applications of the same chemical. Alternating between different classes, groups or formulations of pesticides can minimize the potential for microbial degradation problems as well as pest resistance.

Minor Use Priority – EPA will expedite the registration process for use of a pesticide on minor use crops. In addition, if a “vulnerable crop” that is also a minor use crop is identified by the USDA/EPA due to a crop/pest specific combination, this will become an EPA priority for registration.

Monitoring Well – 1. A well used to obtain water quality samples or measure groundwater levels. 2. A well drilled at a hazardous waste management facility or Superfund site to collect ground-water samples for the purpose of physical, chemical, or biological analysis to determine the amounts, types, and distribution of contaminants in the groundwater beneath the site.

Monoclonal Antibodies (MABs/MCAs) – 1. Man-made (anthropogenic) clones of a molecule, produced in quantity for medical or research purposes. 2. Molecules of living organisms that selectively find and attach to other molecules to which their structure conforms exactly. This could also apply to equivalent activity by chemical molecules.

Mutagenic – Capable of causing genetic changes.

Mycoplasmas – The smallest known living organisms that can reproduce and exist apart from other living organisms. They obtain their food from plants.

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Necrosis – Localized death of tissue usually characterized by browning and desiccation.

Nematodes – Small, usually microscopic, eel-like roundworms.

Nitrogen Fixation – Conversion of nitrogen in air to nitrogen compounds which plants can use, by soil organisms or organisms living in nodules on legume roots.

Non-Community Water System (NCWS) – A public water system that is not a community water system; e.g., the water supply at a campsite or national park. See Community Water System.

Non-Incorporated – A pesticide application to the soil surface, which enters the soil only by rainfall.

Non-Point Sources – Diffuse pollution sources (i.e., without a single point of origin or not introduced into a receiving stream from a specific outlet). The pollutants are generally carried off the land by storm water. Common non-point sources are agriculture, forestry, urban, mining, construction, dams, channels, land disposal, saltwater intrusion, and city streets.

Nonporous Surfaces – Surfaces that have no openings to allow liquid to be absorbed or pass through.

Nonselective – An herbicide that is generally toxic to most plants treated. Some selective herbicides may become nonselective at high rates.

Non-Target Organism – Any plant or animal other than the pest that is being controlled.

Non-Transient Non-Community Water System (NTNCWS) – A public water system that regularly serves at least 25 of the same non-resident persons per day for more than six months per year.

No Observed Adverse Effect Level (NOAEL) – An exposure level at which there are no statistically or biologically significant increases in the frequency or severity of adverse effects between the exposed population and its appropriate control; some effects may be produced at this level, but they are not considered as adverse, or as precursors to adverse effects. In an experiment with several NOAELs, the regulatory focus is primarily on the highest one, leading to the common usage of the term NOAEL as the highest exposure without adverse effect.

No Observed Effect Level (NOEL) – Exposure level at which there are no statistically or biological significant differences in the frequency or severity of any effect in the exposed or control populations.

No-Till – A soil-conserving crop production system in which the crop seed is planted into stubble or sod with no soil disturbance other than the planting operation.

Noxious weed – A plant identified by law as being undesirable, troublesome, and difficult to control. Laws may mandate control of noxious weeds and may restrict presence of their seed in crop seed offered for sale.

Nozzle – The output device of a sprayer. Common nozzle types are flat fan (broadcast applications), full and hollow cone (foliar insecticides and fungicides). and even (banded applications).
Office of Pesticide Programs (OPP) – This EPA office regulates the use of all pesticides in the United States and establishes maximum levels for pesticide residues in food, thereby safeguarding the nation’s food supply.

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Office of Prevention, Pesticides, and Toxic Substances (OPPTS) – This EPA office promotes the use of safer chemicals, processes, and technologies; promotes life-cycle management of environmental problems such as asbestos; advances pollution prevention through voluntary action by industry; and promotes the public’s right to know.

Offsite – Outside the area where the pesticide is being released.

Oncogenic – Capable of producing or inducing tumors in animals, either benign (noncancerous) or malignant (cancerous).

Organic Farming – A production system, which avoids or largely excludes the use of synthetic fertilizers, pesticides, growth regulators, and livestock feed additives. To the maximum extent feasible, organic farming systems rely upon such techniques as crop rotations, crop residues, animal manures, legumes, green manures, mechanical cultivation, and aspects of biological pest control to maintain soil productivity and tilth, to supply plant nutrients, and to control insects, weeds and other pests.

Organic Matter – Plant and animal residues at various stages of decomposition, soil organisms, and substances synthesized by them.

Organophosphate Alternative Pesticide – An OP alternative pesticide is a pesticide that has efficacy on some of the same pest/crop combinations as the OP, but uses a different mode of action than the OP. Use of an OP alternative is the EPA’s initiative to reduce the use of organophosphate (OP) pesticides, since the OP pesticides produce their pesticidal effects through neurotoxicity. An OP Alternative Status does not guarantee that the product will get a registration.

Overland Flow – The quantity of water that moves across the land surface. Contributions to overland flow are from runoff and from the surfacing of subsurface flows before they reach a receiving stream or a defined drainage channel.

Overseeding – Seeding one crop broadcast in another. Overseeding is common in turf and pastures.

Overwintering Stage(s) – How an organism survives the winter. It is important to understand overwintering stages in order to develop an integrated pest management approach which minimizes overwintering of pests in or on the seed of the host, in overwintering (dormant) plants, in insect vectors, in perennial wild hosts, in debris of infected plants, or in soil.

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Parasite – An organism living on or in another living organism (host) and obtaining its food from the latter.

Pathogen – An organism that causes disease in other organisms.

Penetrant – A chemical that helps a pesticide active ingredient to get through a surface of an organism.

Perennial – A plant that lives for more than 2 years. In cold climates the exposed tops of many weeds may freeze, but they grow back from vegetative parts at, or below, the soil surface.

Personal Protective Equipment (PPE) – Devices and clothing worn to protect the human body from contact with pesticides or pesticide residues.

Pest Management Regulatory Agency (PMRA) – All products designed to manage, destroy, attract or repel pests that are used, sold or imported into Canada are regulated by Health Canada’s Pest Management Regulatory Agency. These products include chemicals, devices, and even organisms, and are referred to collectively as pest control products, or simply “pesticides.” The federal legislative authority for the regulation of pesticides in Canada is the Pest Control Products Act. The use of pesticides is also subject to regulation under provincial/territorial legislation.

Pesticide Registration Notice (PR Notice) – A PR Notice is issued by the EPA to clarify and/or provide additional guidance to the registrants regarding EPA policies or rules. The PR Notice is given a unique number that identifies it according to both the year and the sequence of issue within the year of issue. For example “PR Notice 98-7” was the 7th notice issued in 1998.

Pesticides, Proper Handling – These include selection, measuring, mixing, loading, calibration, application, cleanup, disposal, storage, and spill containment.

  1. Selection – Know your pesticides. Always check pesticide labels to determine lowest rates needed to control the target pest(s), registered crops and geography, and factors influencing control.
  2. Measuring/Mixing/Loading – Before mixing the pesticide with water, check the water for pH and minerals that may greatly reduce pesticide efficacy. Generally, insecticides are more sensitive to pH and herbicides are more sensitive to mineral constituents such as calcium, magnesium, and sodium. Consult the pesticide label for recommendations about how to maintain efficacy with varying water quality. Maintain as much distance as possible between the well and the pesticide mixing and loading site, using a long hose or filling the tank in the field using an alternative water source. Wherever possible, do these operations over an impermeable surface that drains to a sealed catchment. Use closed-handling systems for mixing pesticides where practical, which consist of a pump and series of pressure hoses that allow the user to siphon concentrated pesticide and mix with water without direct contact with the chemical. Prevent spillage and back-siphoning from spray equipment into the well by preventing overflow, maintaining an air gap between the filling hose and the water level in the tank, and using an anti-backflow device (check-valve) on the filling hose, especially when siphoning water directly from a pond or stream (properly-constructed wells have check-valves, or these can be added to an existing system). Never leave the sprayer alone while filling. If pesticides are back-siphoned into a well or hydrant, immediately a) pump the well to minimize pesticide movement into the aquifer and report the incident to the appropriate authorities. The authorities will provide action steps, including proper disposal of the pumped water and contaminated soil.
  3. Calibration/Application – Calibrate application equipment and perform nozzle maintenance regularly to ensure that the proper amount of pesticide is applied.
  4. Cleanup/Disposal – Rinse chemical containers thoroughly as soon as they are emptied, using the triple rinse method or a pressure rinser, and use rinsate as part of the spray solution. Use of dissolvable packaging, reusable containers, or returnable containers avoids the problems associated with finding a suitable disposal site for empty containers. Properly dispose of unused pesticides that have been banned or are no longer wanted, to prevent potential leakage. Clean the application equipment properly, over an impermeable surface that drains to a sealed catchment. The need for a rinsing pad and storage of rinsate can be avoided by taking clean water to the field in a separate tank to clean equipment. Clean in a way that makes it easy to collect rinsates. Excess spray solution and rinsate from either type of equipment cleaning can be sprayed on another site or crop listed on the label, or used the next time that chemical or tank mix is applied; however, it is always preferable that excess spray solution not be prepared. Never dispose of pesticides or pesticide containers near a water source, over shallow water tables, in sinkholes or in abandoned wells. Excess pesticides can be given to another qualified user, taken to a qualified disposal site, safely stored until there is a hazardous waste collection day, or disposed of through a hazardous waste transporter.
  5. Storage – Pesticide inventory should be adequate but not excessive. Store pesticides in their original container in a secure, cool, well-ventilated location with a concrete floor sealed with an impermeable surface material. All drains must be self-contained or plugged. The building should be located down-slope and as far away from the well and other water sources as possible. It should not be located in areas that flood or that have standing water for any length of time. Each pesticide container should have its label plainly visible with the date of storage clearly marked. Containers should be inspected regularly for leaks and corrosion, and the proper equipment and materials to rapidly respond to a spill should be easily accessible in the storage area. Bulk pesticide storage tanks should also be inspected frequently and placed on concrete pads with dikes built around them to prevent the movement of pesticides if there is a spill or leak.
  6. Spills – Attend to all pesticide spills immediately. Secure medical attention, contain the spill, and contact the appropriate authorities. Do not hose down the spill, which will spread it. Cover the area of the spill with an absorbent and/or neutralizing material recommended by the pesticide manufacturer. Shovel or sweep the clean-up material and affected soil into a leak-proof drum and dispose of it according to local regulations for contaminated materials.

pH (Liquid) – An expression of the intensity of the basic or acid condition of a liquid; may range from 0 to 14, where 0 is the most acid and 7 is neutral. Natural waters usually have a pH between 6.5 and 8.5.

pH (Soil) – The degree of acidity or alkalinity in the soil, affecting the availability of nutrients, the activity of microorganisms, and chemical breakdown reactions, especially acid hydrolysis, which nearly ceases above pH 6.8. Acid hydrolysis affects primarily triazines and some sulfonylurea herbicides. Soil pH influences adsorption and availability of some pesticides (such as imidazolinones, sulfonylureas, triazines, and triazolopyrimidines) by determining the electrical charge of the molecule. Molecules become negatively (-) charged when a proton (H+) is removed or become positively (+) charged when a proton is added. Pesticide molecules are adsorbed to soil particles when they become (+) charged due to attraction to (-) charges on soil particles.

Pheromones – Chemicals emitted by an organism to influence the behavior of other organisms of the same species.

Photodecomposition – The breakdown of pesticides by light, particularly sunlight. Photodecomposition can destroy pesticides on foliage, on the surface of the soil, and even in the air. Factors that influence pesticide photodecomposition include the intensity of the sunlight, properties of the application site, the application method, and the properties of the pesticide. Pesticide losses from photodecomposition can be reduced by incorporating the pesticide into the soil during or immediately after application.

Phytotoxic – Injurious or lethal to plants.

Plant Growth Regulator (PGR) – An organic compound effective in minute amounts for controlling or modifying plant growth processes without much phytotoxicity.

Plasmid – A circular piece of DNA that exists apart from the chromosome and replicates independently of it. Bacterial plasmids carry information that renders the bacteria resistant to antibiotics. Plasmids are often used in genetic engineering to carry desired genes into organisms.

Plow Layer – The upper 6 2/3 inch of the soil profile, usually calculated as 2 million lbs/A. It is always desirable to retain pesticides which reach the soil in the plow layer, where biological and chemical reactions can degrade them to simple compounds like water and carbon dioxide.

Point Source – A stationary location or fixed facility from which pollutants are discharged; any single identifiable source of pollution; e.g., a pipe, ditch, ship, ore pit, factory smokestack.

Pollution, Pesticidal – Pesticides affecting the environment in undesirable ways. These include effects on non-target organisms (plants, wildlife, humans, etc.) or sites (lakes, rivers, groundwater, etc.) through over-application, drift, carryover, run-off, and leaching. Many stewardship practices involving farm management and pesticide handling can reduce the potential for contamination. There are many stewardship techniques which prevent or minimize pollution, such as integrated pest management, careful selection, measuring, mixing, loading, disposal, and storage of pesticides, accurate calibration and maintenance of application equipment, careful consideration of the vulnerability of the area, proper location and upkeep of wells, use of best management practices (such as leaving a border of untreated vegetation between treated and sensitive areas), and delaying application if heavy or sustained rain is predicted.

Porous Surfaces – Surfaces that have tiny openings, which allow liquid to be absorbed or to pass through.

Postemergence (Post) – Application of a pesticide after emergence of the crop; or application of an herbicide after emergence of the target weeds (may be pre or post to crop). The range of growth stages of both crop and weeds are specified on herbicide labels to ensure proper application timing.

Post-Harvest – An application of an insecticide or fungicide to the harvested commodity prior to or in storage; or an application of an herbicide to fallow (unplanted) ground after crop harvest.

Potable Water – Water that is safe and palatable for human consumption.

Precautionary Statement – Pesticide labeling statement that alerts you to possible hazards from use of the pesticide product and that may indicate specific ways to avoid the hazards.

Predator – An organism that attacks, kills, and feeds on other organisms.

Preemergence (Pre) – Application of a pesticide after planting but before emergence of the crop; or application of an herbicide before emergence of the target weeds (may be pre or post to crop). The range of growth stages of both crop and weeds are specified on herbicide labels to ensure proper application timing.

Pre-Harvest Interval (PHI) – The time between the last pesticide application and harvest of the treated crops.

Prepack – A pesticide formulation containing more than one active ingredient.

Preplant – Before planting or transplanting a crop, either as a foliar application to control existing vegetation or as a soil application. Most commonly refers to herbicides.

Preplant Incorporated (PPI) – A preplant broadcast incorporated application (applied to the entire soil surface and mixed in by tillage before crop seeding or transplanting).

Primary Infection – The first infection of a plant by the overwintering or oversummering pathogen.

Primary Inoculum – The overwintering or oversummering pathogen, or its spores, that cause primary infection.

Priority List – EPA’s initiative to prioritize and/or expedite the review of regulatory submissions. Priorities for EPA are as follows: methyl-bromide alternatives; OP alternatives that pass the reduced-risk screen; other reduced-risk candidates; OP alternatives that are recommended by the reduced-risk committee for expedited review; crops identified by USDA and EPA as potentially vulnerable; minor use crop priorities; non-minor use priorities; and trade irritants. In addition to the EPA priorities, the registrants may submit a list of their company priorities that do not fit into a designated position in the EPA list, but are important registration priorities to the registrant. EPA will place the registrant priorities into the EPA workplan and they will proceed into review as EPA time and resource permits.

Propagule – The part of an organism that may be disseminated and reproduce the organism.

Protectant – See Antidote.

Publicly Owned Treatment Works (POTWs) – A waste-treatment works owned by a state, unit of local government, or Indian tribe, usually designed to treat domestic wastewaters.

Public Water System (PWS) – A system that provides piped water for human consumption to at least 15 service connections or regularly serves 25 individuals.

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Qualitative Use Assessment – Report summarizing the major uses of a pesticide including percentage of crop treated, and amount of pesticide used on a site.

Quality Assurance/Quality Control (QA/QC) – The policy, procedures, and systematic actions established in an enterprise for the purpose of providing and maintaining a specified degree of confidence in data integrity and accuracy throughout the lifecycle of the data.

Quarantine – Control of import and export of plants to prevent spread of diseases and other pests.

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Raw Agricultural Commodity (RAC) – An unprocessed human food or animal feed crop (e.g., raw carrots, apples, corn, or eggs).

Raw Water – Intake water prior to any treatment or use.

Reasonable Maximum Exposure – The maximum exposure reasonably expected to occur in a population.

Reasonable Worst Case – An estimate of the individual dose, exposure, or risk level received by an individual in a defined population that is greater than the 90th percentile but less than that received by anyone in the 98th percentile in the same population.

Recharge Area – A land area in which water reaches the zone of saturation from surface infiltration, e.g., where rainwater soaks through the earth to reach an aquifer.

Recharge Rate – The quantity of water per unit of time that replenishes or refills an aquifer.

Recombinant Bacteria – A microorganism whose genetic makeup has been altered by deliberate introduction of new genetic elements. The offspring of these altered bacteria also contain these new genetic elements; i.e. they “breed true.”

Recombinant DNA – The new DNA that is formed by combining pieces of DNA from different organisms or cells.

Reduced-Risk Pesticide – The status assigned to a pesticide by the EPA’s Reduced-Risk Committee, which determines that the pesticide is a reduced-risk to human health and the environment when compared to the existing alternative products. The major incentive the EPA offers to the manufacturers of Reduced-Risk pesticides is an expedited registration review process. A reduced risk status does not guarantee that the product will get a registration. Participation in the EPA Reduced-Risk initiative is voluntary, requiring that the registrant prepare a reduced-risk rationale, or “safer” document, that presents the case for establishing a pesticide as a reduced risk when compared to other existing pesticides currently being used to control the same pests in the same crops. Significant characteristics for a pesticide to be placed in the status of reduced-risk are reduced human health risks; low toxicity to beneficial insects, birds, and fish; low potential for groundwater contamination; low use rates; low potential for resistance; high compatibility for IPM; and highly efficacious.

Reduced-Risk Rationale – Participation in the EPA Reduced-Risk initiative is voluntary. Consequently, the EPA requires information on the pesticide via the Reduced-Risk Rationale (commonly referred to as a “safer” document). The document is compiled by the registrant and presents the case for establishing a pesticide as a reduced risk when compared to other existing pesticides currently being used to control the same pests in the same crops. The Reduced-Risk Rationale is presented to the Reduced-Risk Committee for review and evaluation of the subject pesticide. Significant characteristics for a pesticide to be placed in the status of reduced-risk are: reduced human health risks; low toxicity to beneficial insects, birds, and fish; low potential for groundwater contamination; low use rates; low potential for resistance; high compatibility for IPM; and highly efficacious.

Reentry Interval (REI) – The period of time immediately following the application of a pesticide during which unprotected workers should not enter a field.

Reference Dose (RfD) – The concentration of a chemical known to cause health problems; also referred to as the ADI, or acceptable daily intake. Also defined as an estimate (with uncertainty spanning perhaps an order of magnitude) of the daily exposure (mg/kg/day) to the human population (including sensitive subgroups) that is likely to be without risk of deleterious effects during a lifetime. The RfD is a benchmark dose derived from the No Observed Adverse Effect Level (NOAEL) or Lowest Observed Adverse Effect Level (LOAEL) by application of uncertainty factors that reflect various types of data used to estimate RfDs and an additional modifying factor, which is based on a professional judgment of the entire database of the chemical. RFD = NOAEL or LOAEL / (UF * MF). See Uncertainty Factor.

Renovation – Establishment of desirable legumes and grasses in grass sod without plowing.

Reregistration Eligibility Document (RED) – RED’s summarize the finding of the review process and reflect EPA’s decision to impose any new conditions on the use of a pesticide, to call-in product specific data, or to take other actions on an existing product registration. RED’s also involve the “Special Review” process, which requires risk and benefit analyses along with the opportunity for public comment processes.

Residue – The part of a pesticide or its metabolites that remains in the environment (in the soil, in water, or on plants or animals) for a period of time following application or a spill. Also see Soil Residue.

Resistance to Pesticides – Adaptation of a pest to withstand exposure to a pesticide that it was susceptible to in the past. There is no general agreement as to the distinction between tolerance and resistance, but there are a variety of strategies to reduce the development of resistance. Plant pest-resistant crop varieties, maintain competitive crop growth, and rotate crops, particularly those with different life cycles and thus different pest problems. Do not use pesticides with the same mode of action in the different crops unless other effective control practices are also included. Use pesticides only when necessary (based on economic thresholds), rotate pesticides with different modes of action, and apply pesticides in tank-mix, prepacks or sequential applications which include multiple modes of action and are effective on the potentially resistance species. Alternate or combine with non-pesticide control methods. Control alternate hosts of insects and diseases, use tillage (but avoid erosion), use biocontrol if available, and use preventative control where resistance is occurring. Scout fields regularly and respond quickly to changes in pest populations. Clean tillage and harvest equipment before moving from fields infested with resistant species. Individuals responsible for total vegetation control in non-crop situations must also be vigilant because high rates used in these programs favor resistance.

Responsible Industry for a Sound Environment – A national not-for-profit trade association representing producers and suppliers of specialty pesticides and fertilizers. Established in 1991, RISE serves as a resource and advocate on pesticides and fertilizers and provides information on issues and research affecting the industry. The association also monitors legislative and regulatory issues in Washington, D.C. and in the states. Specialy pesticide uses include structural pest control, turf and ornamentals, vegetation management, nursery and greenhouse, forestry, aquatics, and public health.

Restricted Entry Interval (REI) – The time after a pesticide application during which entry into the treated area is restricted.

Restricted-Use Pesticide – A pesticide that is available for purchase and use only by certified pesticide applicators or persons under their direct supervision, because it requires special handling due to a relatively high potential for human, environmental, or other hazards.

Rinsate – Pesticide-containing water (or another liquid) that results from rinsing a pesticide container, pesticide equipment, or other pesticide-containing materials.

riparian buffer

Riparian buffer

Riparian Buffer – Trees, shrubs, and/or permanent grasses planted along a stream or river to intercept pollutants and erosion.

Riparian Habitat – Areas adjacent to rivers and streams with a differing density, diversity, and productivity of plant and animal species relative to nearby uplands.

Risk Assessment – Qualitative and quantitative evaluation of the risk posed to human health and/or the environment by the actual or potential presence and/or use of specific pollutants.

Risk Cup – An analogy used by the EPA to visualize the risk for aggregate exposure estimates as well as cumulative exposure estimates. The aggregate exposure estimate is the total allowance for exposures to a single pesticide. The cumulative exposure estimate is the total allowance for exposures to a number of pesticides having the same mode and/or mechanism of action. This includes both dietary and residential exposure. (Note: Cumulative exposure estimates are currently being defined for pesticides with the same mode and/or mechanism of action). For more information, refer to the aggregate risk and cumulative risk definitions described below. The full-cup represents the total allowable reference dose, including all uncertainty factors considered by the toxicity of the pesticide. If a risk cup is full or exceeded, no new uses can be approved until the risk level is lowered. For example, the registrant could provide new data indicating lower exposures or hazards for consideration by the EPA. Also see FQPA.

  1. Aggregate Risk – The aggregate risk is an assessment of combined exposures (non-occupational human exposure and risk from a single chemical) by all relevant pathways or routes of exposure. EPA is currently considering food, drinking water, and residential scenarios for oral exposure and residential scenarios for exposure through the skin.
  2. Cumulative Risk – FQPA requires that the Agency assess the potential risk of cumulative exposure to related chemicals which share a common mechanism of toxicity. The organophosphate pesticides were selected as the first group of related pesticides to be examined for cumulative effects. The EPA is searching the available data and compiling tables, or matrices, which display information, crop by crop, about the amount of each OP pesticide used, what critical pests it is used to combat, and, where available, information about regional differences in use patterns. These draft matrices are being posted to the Internet to allow public access.

Risk (Adverse) for Endangered Species – Risk to aquatic species if anticipated pesticide residue levels equal one-fifth of LD10 or one-tenth of LC50; risk to terrestrial species if anticipated pesticide residue levels equal one-fifth of LC10 or one-tenth of LC50.

Risk for Non-Endangered Species – Risk to species if anticipated pesticide residue levels are equal to or greater than LC50.

Rosette – The overwintering stage of winter annual, biennial, and certain perennial broadleaf plants characterized by tightly clustered leaves before the internodes expand and flowering occurs; weeds are usually more resistant to herbicides once they reach this stage.

Route of Exposure – The avenue by which a chemical comes into contact with an organism, e.g., inhalation, ingestion, dermal contact, injection.

Runoff – The movement of rainfall, snow melt, or irrigation water across the land over a sloping surface rather than through the soil; the latter is leaching. Runoff occurs when water is applied faster than it can infiltrate the soil, and is a major transporter of non-point source pollutants into rivers, streams, and lakes. Pesticides and other chemicals from the air and land can be carried in the water itself or bound to eroding soil particles. The severity of pesticide runoff depends on the slope or grade of an area; the erodibility, texture and moisture content of the soil; and the amount and timing of rainfall and irrigation. Pesticide runoff usually is greatest when a heavy or sustained rain follows soon after an application. Over-irrigation can lead to excess surface water; it also can lead to pesticide runoff, especially when an irrigation system is used to apply a pesticide. Vegetation or crop residue tends to slow the movement of runoff water. Certain physical and chemical properties of the pesticide, such as how quickly it is absorbed by plants or how tightly it is bound to plant tissue or soil, are also important. Pesticide runoff can contaminate ground or surface waters, harm aquatic organisms in streams, lakes, and ponds, or cause injury to crops, livestock or humans if the contaminated water is used downstream. Runoff can be reduced by monitoring weather conditions, careful application of irrigation water, using a spray mix additive to enhance pesticide retention on foliage, and incorporating the pesticide into the soil. Reduced-tillage cropping systems and surface grading, in addition to BMPs such as contour planting and strip cropping of untreated vegetation, can slow the movement of runoff water and help keep it out of wells, sinkholes, water bodies and other sensitive areas.

Runoff Application – A pesticide application where spray is applied until it begins to drip off the plant leaves.

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Safener – A chemical added to a pesticide to keep it from injuring plants. See Antidote.

Safe Drinking Water Act – Act passed in 1974 to protect public health by regulating the nation’s public drinking water supply. SDWA applies to every public water system in the United States (>170,000), but does not regulate private wells that serve fewer than 25 individuals. SDWA provides a framework in which USEPA, states, tribes, water systems and the public work together to protect the public drinking water supply.

Safe Water – Water that does not contain harmful bacteria, toxic materials, or chemicals, and is considered safe for drinking even if it may have taste, odor, color, and certain mineral problems.

Saturated Zone – The area below the water table where all open spaces are filled with water under pressure equal to or greater than that of the atmosphere.

Scouting – Regularly searching for, identifying, and assessing numbers of pests and the damage they are causing.

Secondary Infection – Any infection caused by secondary inoculum, which is produced as a result of a primary or a subsequent infection.

Secondary Inoculum – Inoculum produced by infections that took place earlier during the same growing season.

Selective – A pesticide that is more toxic to some weeds, insects, or diseases than to others.

Sensitive Areas – Sites or organisms that are particularly vulnerable to harmful effects from pesticides.

Side-Dress – Application of fertilizer (or fertilizer plus pesticide) beside the rows of emerged row crops like corn or cotton.

Signal Words – The words used on a pesticide label -Danger, Warning, Caution – to indicate level of toxicity.

Sink – Place in the environment where a compound or material collects.

Sod – The close network of roots and rhizomes of one or more grass species.

Soil Application – Application of an herbicide made primarily to the soil surface rather than to vegetation.

Soil Conditioner – An organic material like humus or compost that helps soil absorb water, build a bacterial community, and take up mineral nutrients.

Soil Erodibility – An indicator of a soil’s susceptibility to raindrop impact, runoff, and other erosive processes.

Soil Incorporation – Mechanical mixing or leaching in with water of a pesticide into the surface soil to facilitate uptake by pests or crop, or to reduce its loss by volatility or photodecomposition.

Soil Residual Life – The length of time that a pesticide remains active in the soil.

Soil Residue – When a pesticide remains in the soil after the target crop has been harvested.

Soil Texture – Relative proportion of sand, silt, and clay in the soil. Soils with high sensitivity to groundwater contamination have a coarse texture (high proportion of sand) and relatively low relief.

Soil Water Zone – The zone extending from the land surface down through the major root zone, capable of holding water. Therefore, its total depth is variable and is dependent upon soil type and vegetation. This zone is unsaturated except during periods of heavy infiltration and percolation.

Solvent – A liquid, such as water, kerosene, xylene, or alcohol, that will dissolve a pesticide (or other substance) to form a solution.

Special Review – Formerly known as Rebuttable Presumption Against Registration (RPAR), this is the regulatory process through which existing pesticides suspected of posing unreasonable risks to human health, non-target organisms, or the environment are referred for review by EPA. Such review requires an intensive risk/benefit analysis with opportunity for public comment. If risk is found to outweigh social and economic benefits, regulatory actions can be initiated, ranging from label revisions and use restrictions to cancellation or suspended registration.

Species – A reproductively isolated aggregate of interbreeding organisms having common attributes and usually designated by a common name.

Specific Conductance – Rapid method of estimating the dissolved solid content of a water supply by testing its capacity to carry an electrical current.

Spore – The reproductive unit of fungi consisting of one or more cells; it is analogous to the seed of green plants.

spot treatment

Spot treatment

Spot Treatment – An herbicide application to random areas of the field, where patches of weeds exist. This practice is particularly common for hard-to-control perennials in pastures or rangeland, where broadcast application would be wasteful, cost prohibitive, and/or injurious to the crop.

Sprayers –

  1. Air-Blast – Similar to a high pressure sprayer in use, advantages, and disadvantages, except pump pressure is low because air moves the spray droplets.
  2. High Pressure (Hydraulic) – A pesticide sprayer providing better coverage and penetration than low pressure sprayers, and thus commonly used for insecticide and fungicide applications on fruits, vegetables, trees, and landscape plants. Cost and drift are greater with a high versus a low pressure sprayer.
  3. Low Pressure – The most common pesticide sprayer for field crops, pastures, non-crop use, and most herbicide applications, characterized by low volume, low pump pressure, and limited agitation

Spray Solution – What is applied to the field when a pesticide formulation is added to a liquid carrier (water, liquid fertilizer, oil, etc.) in the spray tank. The spray “solution” is actually a true solution, an emulsion, or a suspension, depending on whether the pesticide formulation dissolves, disperses, or is suspended in the carrier. Emulsions and suspensions can settle without proper agitation before and during application.

Spring – Groundwater seeping out of the earth where the water table intersects the ground surface.

State Management Plan – Under FIFRA, a plan required by EPA to allow states, tribes, and U.S. territories the flexibility to design and implement ways to protect groundwater from the use of certain pesticides.

Static Water Level – Elevation or level of the water table in a well when the pump is not operating.

Stewardship – Any activity that has a positive impact on the safety and efficacy of pesticides from manufacture, marketing and commerce, through storage and use, and ultimately disposal of unwanted or unusable products and the management of emptied containers. Courtesy of The Pesticide Stewardship Alliance.

aerial view of strip cropping

Strip cropping

Strip Cropping – Densely seeded crops alternated with row crops or fallow in long narrow strips across the slope or across the direction of the wind to prevent erosion.

Subchronic Exposure – Multiple or continuous exposures lasting for approximately ten percent of an experimental species’ lifetime, usually over a three-month period.

Submerged Aquatic Vegetation – Vegetation that lives at or below the water surface; an important habitat for young fish and other aquatic organisms.

Superchlorination – Chlorination with doses that are deliberately selected to produce water free of combined residuals, and so large that dechlorination is subsequently needed.

Superfund – The program that funds and carries out EPA solid waste emergency and long-term removal and remedial activities. These activities include establishing the National Priorities List, investigating sites for inclusion on the list, determining their priority, and conducting and/or supervising cleanup and other remedial actions.

Supplemental Registration – An arrangement whereby a registrant licenses another company to market its pesticide product under the second company’s registration.

Surface Drains – Ditches or swales that are designed to help remove excess water from the land surface to a conveyance channel. These are usually constructed as broad, shallow channels that can be crossed with field machinery.

Surface Water – Water stored or flowing at the earth’s surface, including natural bodies of water such as rivers, streams, lakes, ponds, and wetlands, as well as constructed (artificial) water reservoirs such as canals, man-made lakes, irrigation ditches, and storm water drains. Surface water is linked to both groundwater and atmospheric water through the hydrologic cycle. Surface water moves into groundwater by infiltrating the soil and percolating downward; it also enters the atmosphere through evaporation and transpiration. Likewise, water from the atmosphere and groundwater can recharge surface waters. Atmospheric water falls as precipitation: rain, sleet, hail and snow. Groundwater that moves to the earth’s surface contributes to the base flow of streams, lakes, wetlands and other waterways. Precipitation initially infiltrates the top layers of the soil. Continuing precipitation may saturate the upper few inches of the soil, temporarily exceeding its capacity to hold water. Water accumulates on the land surface and moves to lower elevations through surface runoff and may occur across a small or large area. A surface water system is characterized by its watershed or drainage basin.

Surface Water Treatment Rule – Rule that specifies maximum contaminant level goals for Giardia lamblia, viruses, and Legionella and promulgates filtration and disinfection requirements for public water systems using surface water or ground water sources under the direct influence of surface water. The regulations also specify water quality, treatment, and watershed protection criteria under which filtration may be avoided.

Surfactant – An additive that improves the emulsifying, dispersing, spreading, wetting, or other properties of a pesticide spray by modifying its surface characteristics.

Susceptible Species – A pest capable of being injured or killed by moderate application rates of a pesticide.

Suspended Solids/Suspended Loads – Small particles of solid pollutants that float on the surface of, or are suspended in, water or sewage. They are maintained by turbulence and resist removal by conventional means.

Suspension – A substance that contains undissolved particles mixed throughout a liquid.

Sustainable Agriculture – A way of practicing agriculture which seeks to optimize skills and technology to achieve long-term stability of the agricultural enterprise, environmental protection, and consumer safety. It is achieved through management strategies which help the producer select hybrids and varieties, soil conserving cultural practices, soil fertility programs, and pest management programs. Sustainable farming practices commonly include crop rotations, integrated pest management techniques, increased mechanical/biological weed control, more soil and water conservation practices, strategic use of animal and green manures, and use of natural or synthetic inputs in a way that poses no significant hazard to man, animals, or the environment.

Swamp – A type of wetland dominated by woody vegetation but without appreciable peat deposits. Swamps may be fresh or salt water and tidal or non-tidal. See Wetland.

Synergism – An interaction of two or more pesticides such that their combined effect is greater than the predicted effect based on the response to each pesticide applied separately.

Systemic (Translocated) Pesticide– A pesticide that is absorbed and circulated through the vascular system of a plant or animal from the point of entry. Systemic herbicides kill plants by moving to various sites of action, while systemic fungicides and insecticides make the whole plant or animal toxic to pests that feed on it.

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Tailings – Residue of raw material or waste separated out during the processing of crops or mineral ores.

Tail Water – The runoff of irrigation water from the lower end of an irrigated field.

Tank Mixture – Combining two or more pesticides or agricultural chemicals in the spray tank at the time of application. The recommended sequence for addition of two or more formulations to a tank partially filled with water follows the W.A.L.E.S. method: wettable powders or dry flowables -> agitation -> liquid flowables or suspensions -> emulsifiable concentrates or solutions -> surfactants, crop oils, and other adjuvants. Non-registered tank mixes may be applied if all pesticides in the mixture are registered by the Environmental Protection Agency on the crop being treated. However, compatibility testing should be done if the tank mixture is not listed on the label, because the user assumes liability for crop injury and inadequate weed control if the combination is not a labeled tank mixture. Several pesticide combinations have been shown to increase crop injury compared to either pesticide applied alone. For example, crop injury may increase from combinations of bentazon plus malathion, sulfonylurea herbicides plus organophosphate insecticides, and propanil plus organophosphate or carbamate insecticides. Increased crop injury has even occurred with sequential applications of these pesticides.

Target – The site or pest toward which control measures are being directed.

Technical Grade Active Ingredient (TGAI) – A pesticide chemical in pure form as it is manufactured prior to being formulated into an end-use product (e.g., wettable powders, granules, emulsifiable concentrates). Registered manufactured products composed of such chemicals are known as Technical Grade Products.

Teratogenesis – The introduction of nonhereditary birth defects in a developing fetus by exogenous factors such as physical or chemical agents acting in the womb to interfere with normal embryonic development.

Teratogenic – Capable of producing birth defects.

terraced farm field


Terrace – An earthen embankment around a hillside perpendicular to the slope and approximately on a contour, that stops water flow and stores it or guides it safely off a field. Terraces break long slopes into shorter ones. As water makes its way down a hill, terraces serve as small dams to intercept water and guide it to an outlet. There are two basic types of terraces – storage terraces and gradient terraces. Storage terraces collect water and store it until it can infiltrate into the ground or be released through a stable outlet. Gradient terraces are designed as a channel to slow runoff water and carry it to a stable outlet like a grassed waterway.

Theoretical Maximum Residue Contribution – The theoretical maximum amount of a pesticide in the daily diet of an average person. It assumes that the diet is composed of all food items for which there are tolerance level residues of the pesticide. The TMRC is expressed as milligrams of pesticide/kilograms of body weight/day.

Thermal Stratification – The formation of layers of different temperatures in a lake or reservoir.

Thermocline – The middle layer of a thermally stratified lake or reservoir, where there is a rapid decrease in temperatures.

Threshold – The lowest dose of a chemical at which a specified measurable effect (often an adverse effect) is observed and below which it is not observed.

Threshold Level – Time-weighted average pollutant concentration values, exposure beyond which is likely to adversely affect human health.

Threshold Limit Value (TLV) – The concentration of an airborne substance to which an average person can be repeatedly exposed without adverse effects. TLVs may be expressed in three ways – (1) TLV-TWA–Time weighted average, based on an allowable exposure averaged over a normal 8-hour workday or 40-hour workweek; (2) TLV-STEL–Short-term exposure limit or maximum concentration for a brief specified period of time, depending on a specific chemical (TWA must still be met); and (3) TLV-C–Ceiling Exposure Limit or maximum exposure concentration not to be exceeded under any circumstances (TWA must still be met).

Tidal Marsh – Low, flat marshlands traversed by channels and tidal hollows, subject to tidal inundation; normally, the only types of vegetation present are salt-tolerant bushes and grasses. See Wetland.

Tillage – Mechanical soil stirring operations carried on prior to seeding the crop. Various types of equipment are used for tillage, depending on the objective of the tillage. The type and quality of tillage has important environmental impacts. The goal is always optimum pulverization and partial residue coverage because too little or too much will increase run-off. The goal of the final tillage operation (seedbed preparation) is optimum soil particle size reduction to allow close soil contact with the seed while maintaining pores for water and air movement, and a rough surface that dries rapidly and won’t germinate weeds. Cultivation is the preferred term after seeding the crop, though the terms are often used synonymously.

conservation tillage

Conservation tillage

Tillage, Conservation – A broad range of soil tillage systems that leave 30% or more residue cover on the soil surface after planting, substantially reducing the effects of soil erosion from wind and water. These practices also minimize runoff of water, nutrients, and pesticides, improving water storage capacity and farm sustainability. The soil is left undisturbed from harvest to planting except for nutrient amendment. Weed control is accomplished primarily with herbicides, limited cultivation, and cover crops. Where soil erosion by wind is the primary concern, this is any system that maintains at least 1,000 pounds per acre of flat, small grain residue equivalent on the surface throughout the critical wind erosion period. Some specific types of conservation tillage are minimum tillage, zone tillage, no-till, ridge-till, mulch-till, strip-till, and rotational tillage. Reduced-till is NOT a conservation tillage system, but is also defined here.

  1. Minimum-till – Any practice that either eliminates seedbed preparation as a separate operation or combines it with the planting operation.
  2. Mulch-till – The soil is disturbed prior to planting. Tillage tools such as chisels, field cultivators, disks, sweeps or blades are used. Weed control is accomplished with herbicides and/or cultivation.
  3. no till field


    No-till – A planting system where the soil is left undisturbed from harvest to planting except for nutrient injection. Planting or drilling is accomplished in a narrow seedbed or slot created by coulters, row cleaners, disk openers, in-row chisels or rototillers. Weed control is accomplished primarily with herbicides. Cultivation may be used for emergency weed control. Although no-till reduces soil erosion, it may increase the number of soil macropores and pesticide movement through them. Where this is a major factor in water movement, no-till should be modified to include some tillage to disrupt macropore connections with the surface.

  4. Reduced-till – Tillage types that leave 15-30 percent residue cover after planting or 500 to 1,000 pounds per acre of small grain residue equivalent throughout the critical wind erosion period.
  5. ridge tilled field


    Ridge-till – The soil is left undisturbed from harvest to planting except for nutrient injection. Planting is completed in a seedbed prepared on ridges with sweeps, disk openers, coulters, or row cleaners. Residue is left on the surface between ridges. Weed control is accomplished with herbicides and/or cultivation. Ridges are rebuilt during cultivation.

  6. Strip-till – A modification of no-till, mulch-till or other tillage types. Less than 25% row width disturbance is considered no-till. More than 25% row width disturbance is considered mulch-till or another tillage type depending on the amount of residue left after planting.
  7. Zone-till – A modification of no-till, mulch-till or other tillage types. Less than 25% row width disturbance is considered no-till. More than 25% row width disturbance is considered mulch-till or another tillage type depending on the amount of residue left after planting.

Tillage, Conventional – Tillage types that leave less than 15 percent residue cover after planting, or less than 500 pounds per acre of small grain residue equivalent throughout the critical wind erosion period. Generally involves plowing or intensive tillage.

Tillage Equipment – (listed approximately in order from primary tillage to final seedbed preparation)

  1. Moldboard Plow
  2. Standard Disk Plow – 4-10 inch tillage for problem areas such as hard or rocky soil or many roots.
  3. vertical disk plow

    Vertical disk plow

    Vertical Disk Plow – shallow tillage and incomplete residue coverage.

  4. Lister – resembles a double moldboard plus planting attachments, therefore plowing only a portion of the field and resulting in high moisture retention and reduced soil and wind erosion.
  5. Middlebreaker – lister without the planting attachments, to make ridges or beds on which to prepare a seedbed on soils with poor internal drainage.
  6. Subsoiler – breaks up deep (20in) compacted layers of soil to improve their internal drainage; no soil inversion so wind and water erosion are reduced.
  7. chisel plow

    Chisel plow

    Chisel Plow – breaks up 10-12 inches deep; no soil inversion so wind and water erosion are reduced.

  8. Rotary Tiller – uniformly pulverizes the soil and incorporates plant residues and chemicals; should be avoided on sloped land because fine seedbed is conducive to wind and water erosion.
  9. Strip Tiller – rotary tiller that pulverizes strips; less conducive to wind and water erosion if strips run parallel to the contour (perpendicular to the slope).
  10. Cultivator – breaks up 3-5 inches deep with no soil inversion; also used for final seedbed preparation.
  11. Disk Harrow – for final seedbed preparation; produces a seedbed finer than a field cultivator but not as fine as a roller harrow.
  12. Roller Harrow (Cultimulcher) – for final seedbed preparation in residue-free situations.
  13. Tip-and-Pour – Built-in measuring device that fills with a given amount of pesticide when the container is tilted.

Tolerance – (1) Inborn or acquired ability of plants, insects, fungi, etc. to continue normal growth or function when exposed to a potentially harmful agent. There is no general agreement as to the distinction between tolerance and resistance. See Resistance to Pesticides. (2) The maximum amount of a pesticide residue, in parts per million (ppm), that may remain in or on the raw agricultural commodity or its processed fractions. Whenever a pesticide is registered for use on a food or a feed crop, a tolerance (or exemption from the tolerance requirement) must be established. The tolerance is established by the EPA and is enforced by the Food and Drug Administration (FDA) and the Department of Agriculture (USDA).

Total Dissolved Solids(TDS) – All material that passes the standard glass river filter; now called total filterable residue.

Total Maximum Daily Load (TMDL) – An assessment of water quality problems and contributing pollutant sources (incl. pesticides). It identifies numeric targets based on applicable water quality standards (WQS), specifies the maximum amount of a pollutant that can be discharged, allocates pollutant loads among sources, and provides a basis for taking actions needed to meet the numeric target(s) and implement WQS’s. The goal of a TMDL is to attain state water quality standards.

Total Suspended Solids (TSS) – A measure of the suspended solids in wastewater, effluent, or water bodies, determined by tests for total suspended non-filterable solids. See Suspended Solids.

Toxic Substance Control Act – Act that provides information about all chemicals and controls the production of new chemicals that might present an unreasonable risk of injury to health or the environment. TSCA authorizes EPA to require testing of old and new chemical substances, and provides authority to regulate the manufacturing, processing, import and use of chemicals.

Toxicity – The degree to which a substance or mixture of substances can harm humans or animals. Acute toxicity involves harmful effects in an organism through a single or short-term exposure. Chronic toxicity is the ability of a substance or mixture of substances to cause harmful effects over an extended period, usually upon repeated or continuous exposure sometimes lasting for the entire life of the exposed organism. Subchronic toxicity is the ability of the substance to cause effects for some period of time between acute and chronic time frames (ranging from 5 days to more than 1 year, depending in part upon the species evaluated).

Toxicity Assessment – Characterization of the toxicological properties and effects of a chemical, with special emphasis on establishment of dose-response characteristics. See Dose-Response.

Toxicity Testing – Biological testing (usually with an invertebrate, fish, or small mammal) to determine the adverse effects of a compound or effluent.

Transient Non-Community Water System (TNCWS) – A non-community water system that does not serve 25 of the same nonresidents per day for more than six months per year.

Translocated – See Systemic.

Trophic Levels – A functional classification of species that is based on feeding relationships (e.g., generally aquatic and terrestrial green plants comprise the first trophic level, and herbivores comprise the second).

Turbidity – 1. Haziness in air caused by the presence of particles and pollutants. 2. A cloudy condition in water due to suspended silt or organic matter.

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Ultra Low Volume (ULV) – A formulation which requires no additional liquid prior to application through specialized ULV equipment able to apply <0.5 gpa.

Uncertainty Factor (UF) – One of several factors used in calculating the reference dose from experimental data. UFs are intended to account for (1) the variation in sensitivity among humans; (2) the uncertainty in extrapolating animal data to humans; (3) the uncertainty in extrapolating data obtained in a study that covers less than the full life of the exposed animal or human; and (4) the uncertainty in using lowest observed adverse effect level (LOAEL) data rather than no observed adverse effect level (NOAEL) data.

Underground Sources of Drinking Water – Aquifers currently being used as a source of drinking water or those capable of supplying a public water system. They have a total dissolved solids content of 10,000 milligrams per liter or less.

United States Department of Agriculture (USDA) – Government agency that provides leadership on food, agriculture, natural resources, and related issues. The USDA expands markets for US agricultural products, supports international economic development, provides financing to improve rural America, enhances food safety by taking steps to reduce the prevalence of foodborne hazards, provides nutrition education, and manages America’s public and private lands by working cooperatively with other levels of government and the private sector.

Unreasonable Risk – Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), unreasonable adverse effects posing unacceptable risk to man or the environment, taking into account the medical, economic, social, and environmental costs and benefits of the pesticide.

Unsaturated Zone – The area above the water table where soil pores are not fully saturated, although some water may be present.

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Vadose Zone – The zone between land surface and the water table within which the moisture content is less than saturation (except in the capillary fringe) and pressure is less than atmospheric. Soil pore space also typically contains air or other gases. The capillary fringe is included in the vadose zone. See Unsaturated Zone.

Vapor Drift – The movement of a pesticide as a vapor from the area of application usually after the spray droplets have impinged on the target. Also see Drift.

Volatile – Evaporating rapidly; turning easily into a gas or vapor.

Volatile Liquids – Liquids which easily vaporize or evaporate at room temperature.

Volatilization – A process that converts a solid or liquid into a gas. Once volatilized, a pesticide can move in air currents away from the treated surface. Vapor pressure is an important factor in determining whether a pesticide will volatilize. The higher the vapor pressure, the more volatile the pesticide. Certain environmental conditions (high temperature, low relative humidity, air movement, wet soil) increase volatilization. A pesticide tightly adsorbed to soil particles is less likely to volatilize; thus, soil texture, organic matter content, and soil moisture influence pesticide volatilization. Labels often provide warnings if there is a volatility hazard under certain conditions, and may suggest incorporation or irrigation within a certain time period. Low-volatile formulations are also available for some pesticides.

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Water and Sediment Control Basin – A short earthen dam built across a drainageway where a terrace is impractical; usually part of a terrace system. An embankment is built across a depressional area of concentrated water runoff to act similar to a terrace. It traps sediment and water running off farmland above the structure, preventing it from reaching farmland below.

Water-Based Pesticides – Pesticides that use water as the only diluent or carrier.

Water Quality – The chemical, physical, biological, and radiological condition of a surface or ground water body.

Water Quality Criteria – Levels of water quality expected to render a body of water suitable for its designated use. Criteria are based on specific levels of pollutants that would make the water harmful if used for drinking, swimming, farming, fish production, or industrial processes.

Watershed – The area of land draining to a specific water outlet (stream, reservoir, etc.); the boundary is defined by the region’s topography. Watersheds vary in size and can be nested within other larger watersheds. Land use within a watershed largely determines the quality of the local surface water. The quality of water leaving a watershed can, in turn, affect the cumulative quality of water far downstream. For example, pesticides detected in a city’s drinking water supply could come from lawn and other urban uses or from an upstream watershed where agriculture is predominant.

Water Storage Pond/Water Treatment Lagoon – An impound for liquid wastes designed to accomplish some degree of biochemical treatment.

Water Table– The upper level of the groundwater in an area. The water table level fluctuates throughout the year, lowering as water is removed from wells or discharged at streams and springs. The water table rises through recharge from rain and melting snow that seeps through soil into the aquifer. For years it was believed that the natural filtering of water during its slow movement through the soil, sand, gravel and rock formations was adequate to cleanse it of contaminants before it reached groundwater. Today, many chemicals, including some pesticides, have been detected in groundwater. Studies have shown that recharge can carry pollutants down to aquifers. Furthermore, it is clear that human activities can lead to contamination of the recharge water.

Waterway – Any channel, natural or constructed, in which water flows.

Weir – A barrier or dam across a channel to increase water depth and control flow.

Well – A direct conduit from the land surface to groundwater, where pesticides can move directly and rapidly into groundwater. Pesticides can reach groundwater by moving along the outside of the well casing or by entering an improperly capped or sealed well. The method of well construction, the frequency of well inspection and maintenance, and the proximity of a well to pesticides are important factors determining the potential for contamination. Potential sources of both surface and subsurface contamination by pesticides include sites used for storage, mixing, loading, disposal, or application or where equipment is cleaned. Locate and construct new wells according to building codes and site conditions. Inform the well contractor of old dumping pits and pesticide mixing areas. Consider future farm expansion in selecting a site away from changes in pesticide handling and land use that will increase the risk of contamination . Well casing forms the wall of a well. A cement compound of grout is forced into the space between the bore hole and the outside of the well casing to prevent water and contaminants from moving down along the outside of the casing into groundwater. Gravel, sand and other permeable materials are not adequate. The top of the casing must be capped about 8 inches above the ground or at least high enough to prevent surface water from entering the top of the well. Proper well construction includes check-valves to prevent back-siphoning; check-valves can also be added to an existing system. Soil can be graded, or diversion terraces or ditches can be built upslope to intercept or divert surface runoff from the wellhead. Plug abandoned wells with materials that will not allow settling in the future. Never use abandoned wells to dispose of any form of garbage or hazardous material. Some pesticide labels provide minimum distances between pesticide handling and the well location.

Well Field – Area containing one or more wells that produce usable amounts of water.

Wellhead Protection Area – A designated surface and subsurface area surrounding a well or well field that supplies a public water supply and through which contaminants or pollutants are likely to pass and eventually reach the aquifer that supplies the well or well field. The purpose of designating the area is to provide protection from the potential of contamination of the water supply. These areas are designated in accordance with laws, regulations, and plans that protect public drinking water supplies.

Wetland – A land area that is inundated or saturated by surface and/or ground water with a frequency and duration sufficient to support an abundance of hydrophytic (water-loving) plants or other aquatic life that require permanently saturated or seasonally saturated soil conditions for growth and reproduction. Examples include swamps, marshes, bogs, sloughs, potholes, wet meadows, river overflow areas, mud flats, and natural ponds.

Winter Annual – A plant that starts from seed in the fall, lives over winter (usually in a dormant state), and completes its growth, including seed production, the following season.

Worker Protection Standard – Regulation that provides agricultural workers and pesticide handlers in agriculture with protections against possible exposure and harm from pesticides in the workplace.

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Zero Tolerance – Indicates that no detectable amount of the specified pesticide may remain on the raw agricultural commodity when it is sold or utilized.

Photographs Courtesy Of USDA-NRCS. Initial Consolidated Terminology List Courtesy of Syngenta Crop Protection.

Compiled by Dr. Ron Gardner

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