||Definitions provided with permission by the
Washington State Department of Agriculture with
the exception of those with asterisks (*), which
are taken from Thurston County's IPM Policy.
The movement of a chemical into plants, animals (including humans), microorganisms, or soil.
* ACTION LEVEL
The level at which action must be taken to prevent a pest population or vegetation problem at a specific site from reaching the injury level.
The capacity of a pesticide to cause injury from a single exposure. LD50 and LC50 are common
indicators of the degree of acute toxicity. (See CHRONIC TOXICITY)
The property of a substance to stick to a given
A substance added to a pesticide to improve its effectiveness or safety. Same as additive. Examples
are penetrants, spreader-stickers, and wetting agents.
The process by which chemicals are held or bound
to a surface by physical or chemical attraction.
Clay and high organic soils tend to adsorb pesticides.
A pesticide used to kill or inhibit algae.
A plant that completes its life cycle in one year.
A chemical that prevents normal blood clotting.
The active ingredient in some rodenticides.
A permeable zone of rock, sand, gravel, or limestone
below the earth surface saturated with water.
A substance or device to lure insects or other
pests to a trap or poison bait.
Microscopic organisms, some of which are capable
of producing diseases in plants and animals.
A chemical used to control bacteria.
A food or other substance used to attract a
pest to a pesticide or trap where it will be destroyed.
Application to plant stems or trunks at or just
An insect that is useful or helpful to humans.
Examples are pollinators, parasites, and predators
A plant that completes its life cycle in two
A pest management strategy that uses predators,
parasites, and disease-causing organisms. May be
naturally occurring or introduced.
The process where some organisms accumulate
chemical residues in higher concentrates than those
found in the organisms they consume.
The name, number, or designation of a specific
pesticide product or device made by a manufacturer
The uniform application of a pesticide or other
material over an entire field or area.
Plants with broad, rounded, or flattened leaves
with netted veins such as dandelions and roses.
A pesticide that is effective against a wide
range of pests. Usually refers to insecticides and
The ability of a substance or agent to induce
malignant tumors (cancer).
1) An inert liquid, solid, or gas added to an
active ingredient to make a pesticide formulation.
2) The material, usually water or oil, used to dilute
the formulated product for application.
A pest management strategy that involves the
use of naturally derived or synthetic chemicals
that kill, attract, repel, or otherwise control
the growth of pest plants, animals, and microorganisms.
Examples are avicides, insecticides, and rodenticides.
The breakdown of a pesticide by processes not
involving a living organism.
The scientific name of the active ingredient(s)
found in the formulated product. This complex name
is derived from the chemical structure of the active
The yellowing of a plant’s normally green tissue.
The ability of a material to cause injury from
repeated, prolonged exposure to small amounts. (See
A type of applicator certification or license
for an owner or head of a business that commercially
applies pesticides on lands of another.
A type of applicator certification or license for a salesperson who offers technical advice or
recommendations to pesticide users.
A name given to a pesticides active ingredient by a recognized committee on pesticide nomenclature.
Many pesticides are known by a number of trade or brand names, but the active ingredient(s) has only
one recognized common name (e.g., the common name for Sevin insecticide is carbaryl).
Chemicals that can be mixed without reducing the effectiveness of any individual chemical.
The amount of active ingredient in a given volume or weight of formulated product.
A chemical that kills primarily by contact with plant tissue, with little or no translocation.
A compound that causes death or injury to insects upon contact. It does not need to be ingested to
be toxic to the insect.
A pest management strategy that involves the manipulation of the environment to avert serious
pest damage. Examples are crop rotation and pruning.
A chemical that initiates the premature drop of leaves.
The process by which a chemical compound is broken down to a simpler compound by the action
of microorganisms, water, air, sunlight, or other agents. Degradation products are usually, but not
always, less toxic than the original compound.
The ability of a pesticide to cause injury to human or animal when absorbed through the skin.
A chemical that promotes drying or loss of moisture from a leaf or other plant part.
The airborne movement of pesticide spray droplets, dusts, or vapors beyond the intended contact area.
Individual plants or animals with a population that has been reduced to the extent that it is near
Environmental Protection Agency. The federal agency responsible for implementing pesticide rules
and regulations and registering pesticides.
EPA REGISTRATION NUMBER
A number assigned to a pesticide product by EPA when the product is registered by the
manufacturer or the designated agent. The number must appear on all labels for a particular
The complete elimination of a pest from a site.
The pesticide product as purchased, containing a mixture of one or more active ingredients, carriers (inert ingredients), and other additives diluted for safety and ease of application.
A pesticide that forms gases that are toxic to plants and animals when absorbed or inhaled.
A chemical used to control fungi.
GENERAL USE PESTICIDE
A pesticide that can be purchased and used by the general public. Also called UNCLASSIFIED
USE PESTICIDE. (See RESTRICTED USE PESTICIDE)
The sprouting of a seed or production of a germ tube (mycelium) from a fungus spore.
A dry pesticide formulation. The active ingredient is either mixed with or coated onto
an inert carrier to form a small, ready-to-use, low-concentrate particle that does not normally
present a drift hazard. Pellets differ from granules only in their precise uniformity,
larger size, and shape.
Water sources located beneath the soil surface from which well water is obtained or
surface springs are formed.
A chemical that alters the growth processes of a plant or animal.
Employees who handle pesticide products or have high exposure potential. Examples are
mixers, applicators, and flaggers, and equipment repair persons.
The potential for injury or degree of danger involved in using a pesticide under a given set
of circumstances. Depends on both the toxicity of the pesticide and the chance of exposure to
harmful amounts of the chemical.
Plants that do not develop woody tissues.
A pesticide used to kill or inhibit plant growth.
A plant or animal on or in which a pest lives.
Breakdown of a chemical in the presence of water.
An inactive material in a pesticide formulation that does not have pesticidal activity.
Taking in through the lungs; breathing in.
* INJURY LEVEL
refers to the point in the growth of the pest or vegetation problem at which it will cause some unacceptable
level of safety, recreational, public health, ecosystem, aesthetic, or economic injury.
Arthropods characterized by a body composed of three segments and three pairs of legs.
A pesticide used to control or prevent damage caused by insects.
INTEGRATED PEST MANAGEMENT
The use of all suitable pest control methods to keep pest populations below the economic injury level. Methods include cultural practices, use of biological, physical, and genetic control agents, and the selective use of
* INTEGRATED PEST MANAGEMENT (IPM)
An approach to pest and vegetation control that utilizes regular monitoring to determine if
and when treatments are needed. The approach emphasizes physical, mechanical, cultural, and
biological tactics to keep pest numbers or vegetation problems low enough to prevent intolerable damage, annoyance, or public safety
hazards. When chemical controls are necessary, they will be the least toxic available and will
be used only when no other control methods would be effective or practical.
* IPM PRESCRIPTIONS
Control or eradication plans utilizing the principals of IPM that are specific to types of
sites and/or pests and vegetation.
* IPM PROGRAMS
Department-level programs that are developed to implement the Pest and Vegetation Management
All printed material attached to or part of a pesticide container.
(plural of LARVA)—The immature form of an insect or other animal that hatches from an egg.
The concentration of a pesticide, usually in air or water, which can kill 50 percent of a
test population of animals. LC50 is usually expressed in parts per million (ppm). The lower the LC50 value, the more acutely toxic
The dose or amount of a pesticide that can kill 50 percent of a test population of animals
when eaten or absorbed through the skin. LD50 is expressed in milligrams of chemical per kilogram
of body weight of the test animal (mg/kg). The lower the LD50, the more acutely toxic the chemical.
The movement of a substance through soil with water.
A pest management strategy that employs devices to prevent the spread or reduce the
infestation of pests, primarily insects, and vertebrate animals. Examples are hand
destruction, traps, and fences.
A compound derived from changes in the active ingredient through chemical, biological,
or physical reactions. The metabolite may be simpler, more complex, more poisonous, or less
poisonous than the original chemical.
Breakdown of a chemical by microorganisms.
An organism that is so small it cannot be
seen without the aid of a microscope.
MODE OF ACTION
The way in which a pesticide exerts a toxic
effect on a target plant or animal.
A chemical used to control snails and slugs.
involves surveying the problem situation in
order to understand and identify the extent and location
of the problem.
The ability of a substance or agent to cause
genetic changes in living cells.
Death of plant or animal tissues resulting
in the formation of discolored, sunken, or
necrotic (dead) areas.
The ability of a substance or agent to cause
disorders of the nervous system.
A pesticide that is toxic to a wide range of
plants or animals without regard to species. For
example, a nonselective herbicide can kill or
damage all plants it contacts.
Any plant or animal other than the intended
target(s) of a pesticide application.
A plant defined by law as being particularly
troublesome, undesirable, and difficult to
Ability of a pesticide to cause injury when
taken by mouth.
A large group of pesticides that contain the
element phosphorus. Most are nonpersistent insecticides/miticides.
Many are highly toxic. Examples are malathion, parathion,
A plant, animal, or microorganism living in,
on, or with another living organism for the
purpose of obtaining all or part of its food.
A disease-causing organism.
A plant that lives for more than two years.
A pesticide chemical (or its metabolites)
that remains active in the environment more than
one growing season. These compounds sometimes
accumulate in animal and plant tissues. Examples
are DDT, chlordane, and dieldrin.
An undesirable organism (e.g., insect,
fungus, nematode, weed, virus, or rodent)
injurious to humans, desirable plants and
animals, manufactured products, or natural
Any insect, rodent, nematode, snail, slug,
weed and any form of plant or animal life or
virus, except virus on or in a living person or
other animal, that adversely interferes with the
aesthetic, health, environmental, or economic
goals of humans.
Any substance registered by the Washington
State Department of Agriculture as a pesticide.
A chemical or other agent used to kill or
otherwise control pests, or protect from a pest.
PESTICIDE ACTIVE INGREDIENT
A pesticide active ingredient is the chemical responsible for the killing,
suppressing, or repelling action. Thurston County's pesticide review process evaluates
an active ingredient’s chemical properties to aid in the identification of pesticide products with the
least potential hazard. Thurston County’s IPM Policy identifies which chemical hazards are to be evaluated.
Pesticide active ingredients are required to be listed on the product label, but products
may also contain other ingredients not listed on the label. These other ingredients are not supposed to cause any direct killing, suppressing, or repelling action, but they may make a product more effective, aid in application, etc. These other ingredients may also increase or decrease the toxicity (poison hazard) of the product. But, because manufacturers are not required to name the non-active ingredients, Thurston County cannot include them into the pesticide reviews. Therefore, Thurston County does not claim that the active ingredient reviews are reflective of all potential hazards associated with the pesticide products containing them.
Mixtures of active and inert ingredients.
Make an active ingredient more convenient to
handle; safer, easier, and more accurate to
apply; and in some cases more attractive to the
pest. Examples are emulsifiable concentrates,
water-dispersible granules, and fumigants.
A measure of the acidity/alkalinity of a
liquid; acid below pH 7, basic or alkaline above
A substance emitted by an animal to
influence the behavior of other animals of the
same species. Some are synthetically produced
for use in insect traps.
Breakdown of chemicals by the action of
Injury to plants.
After the weed or crop plants have appeared
through the soil. Usually used to specify the
timing of herbicide applications.
Personal protective clothing and equipment.
Intended to protect a person from exposure
during the handling and application of
pesticides. Includes long-sleeved shirts, long
trousers, coveralls, hats, gloves, shoes, and
An animal that attacks, feeds on, and kills
other animals. Examples are hawks, owls, snakes,
fish, and many insects.
Before weeds or crop plants have appeared
through the soil. Used to specify the timing of
A pesticide product formulated with more
than one active ingredient.
A type of applicator certification or
license for a land owner/lessee or employee who
uses restricted use pesticides on cropland or
associated agricultural non-cropland to produce
A type of applicator certification or
license for a land owner/lessee or their
employee who uses restricted use pesticides for
purposes other than producing agricultural
A type of certification or license for a
government agency or utility company employee
who offers technical advice or recommendations
for pesticide use (other than for home or
gardens) during the course of their employment.
The intermediate developmental stage of some
insects between larva and adult.
RATE OF APPLICATION
The amount of pesticide applied to a plant,
animal, unit area, or surface; usually measured
as per acre, per 1,000 square feet, per linear
feet, or per cubic feet.
Pesticide products that have been registered
by the Environmental Protection Agency for the
uses listed on the label.
A compound that keeps insects, rodents,
birds, or other pests away from plants, domestic
animals, buildings, or other treated areas.
A pesticide that continues to remain
effective on a treated surface or area for an
extended period following application.
A pesticide’s active ingredient or breakdown
product(s) that remains in or on a target after
1) A population of organisms that are uninjured
or unaffected by a certain dosage of pesticide chemical
used to control other populations of the same organism successfully.
2) Plants and animals that are unaffected by a pest species.
RESTRICTED USE PESTICIDE
A pesticide that can be purchased only by
certified pesticide applicators and used only by
certified applicators or persons directly under
their supervision. Not available for use by the
general public because of their high toxicities
and/or environmental hazards.
A pesticide used to control rodents.
The movement of water and associated
materials on the soil surface.
A pesticide that is toxic to some pests, but
has little or no effect on other similar
species. Some fungicides are so selective that
they control only water-mold pathogens and no
Required word(s) that appear on pesticide
labels to denote the relative toxicity of the
product: DANGER-POISON used with a skull and
crossbones symbol for highly toxic compounds,
DANGER for skin and eye irritants, WARNING for
moderately toxic, and CAUTION for slightly toxic
To soak or wet the ground surface with a
pesticide. Large volumes of a pesticide mixture
are usually needed to saturate the soil to any
The placement of a pesticide below the
surface of the soil; common application method
for fumigants and termiticides.
A chemical or agent that prevents the growth
of all organisms present in the soil; a
nonselective pesticide. Soil sterilization may
be temporary or permanent depending on the
A liquid such as water, oil, or alcohol that
will dissolve another substance (solid, liquid,
or gas) to form a solution.
Application to small areas.
An adjuvant used to enhance the spread of a
pesticide over a treated surface, thus
increasing the area that a given volume of
liquid will cover.
An adjuvant used to improve pesticide spray
droplet adherence to a plant, animal, or other
Pests that attack and destroy buildings and
other structures, clothing, stored food, and
manufactured/processed goods. Examples are
termites, cockroaches, clothes moths, rats, and
STRUCTURAL PEST INSPECTOR
A type of applicator certification or
license for an individual who inspects a
structure for wood-destroying organisms or
conditions conducive to their development.
Plants that germinate in the spring or
summer and complete their life cycle within one
A component of many adjuvants that improves the
spreading, dispersing, and/or wetting properties of a pesticide
1) A plant, animal, or site affected by a
pest. 2) Pest populations that can be controlled
A chemical absorbed and translocated
within a plant or animal.
The plants, animals, structures, areas, or
pests at which the pesticide or other control
method is directed.
The property of a substance or agent able to
produce abnormalities or defects in living human
or animal embryos and fetuses. These defects are
not usually inheritable.
involves applying a treatment action during the
most vulnerable time in the life cycle of the pest or vegetation
with the least impact on natural enemies.
A regulation that establishes the maximum
amount of pesticide residue (active ingredient
or certain metabolites) that may legally remain
in or on a raw agricultural commodity (food or
feed product) at harvest or slaughter.
The property of organisms, including pests,
to withstand a certain degree of stress, such as
pest attack, poor weather, or pesticides.
Poisonous to living organisms.
The degree or extent that a chemical or
substance is poisonous.
A naturally-occurring poison produced by
plants, animals, or microorganisms. Examples are
the venom produced by black widow spiders and
The movement of materials within a plant or
animal from the site of entry. A systemic
pesticide is translocated.
The property that causes a chemical to evaporate.
The higher the vapor pressure, the more volatile the chemical
or faster it will evaporate.
Ultramicroscopic parasites composed of
proteins. Viruses can only multiply in living
tissues and cause many animal and plant
The change of a substance from a liquid or
solid state to a gas at ordinary temperatures
when exposed to air.
An unwanted plant.
An adjuvant used to reduce the surface
tension between a liquid and contact surface for
more thorough coverage.
Plants that germinate in the fall and
complete their life cycle within one year.
Washington State Department of Agriculture.
A regulatory agency that administers the
Washington Pesticide Application Act of 1961 and
the Washington Pesticide Control Act of 1971.