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Lawn Glossary Articles - Bio Green Outdoor Services Learning Center

Chemical Control

Pesticides are chemicals used to destroy pests, control their activity or prevent them from causing damage.  Pesticides are generally the fastest way to control pests. Proper ID of the pest and selecting the correct chemical...


a plant that produces a seed with two cotyledons. Characterized by broad, net-veined leaves, flower parts in 4's or 5's, tap-root system, cambium in stems and roots, embryos with two cotyledons and other characters.  (First leaves which appear as a new plant comes up...

Perennial Weeds

Herbaceous plants that live for more than two years. Weeds that live for only for two years are called biennials. (Trees and shrubs are perennials.)


Pesticide material that is carried away from an area by the flow of surface water.

Chronic Toxicity

That which is manifest when toxicants act upon the body over a long period of time, such as daily exposures.


Microscopic, unsegmented roundworms, found in moist earth, water, and decaying matter or as parasites of plants and animals.


The stage between the larva and the adult in insects with complex metamorphosis, a non-feeding and usually inactive stage.


An adverse physiological state of a plant due to an unfavorable environment, nutrient deficiency or imbalance, injury, etc., which is reflected in poor plant growth.


Any plant which grows where it is not wanted.

Aerosol pesticide

a pesticide stored in a container under pressure. Driven through a fine opening by an inactive gas under pressure when the nozzle is triggered.


Refers to the amount of active ingredient in a given volume or weight of diluent. Recommendations and specifications for concentration of herbicides should be on the basis of pounds per unit volume of liquid diluent or percent by weight of solid diluents.


A plant’s “relative ability” to withstand cold temperatures.

Integrated Pest Management (IPM)

combines appropriate pest-control tactics (biological, cultural, and chemical controls) into a single strategy to reduce pests and their damage to an acceptable level.


refers to the amount of active ingredient of a pesticide applied per unit area (such as on an acre). Rate is preferred to the occasionally used terms dosage and application.


Particles of a pesticide, dispersed, and suspended in liquids such as water and oils, e.g. wettable powders.


Not shielded or protected; to come in contact with the pesticides.

Selective Herbicide

Chemical which will kill some plants and leave others relatively unharmed, such as weeds growing in crop plants, e.g. 2,4-D,2,4,5-T, sulfuric acid, dinitro compounds, etc.

LD 50 (Lethal dose 50)

Amount of pesticide required to kill 50% of a test animal population in a single dose. Usually expressed in terms of milligrams of pesticide per kilogram of body weight of the test animals. LD 50 may be expressed for dermal, oral or inhalation amounts.

Parallel Venation

Leaf veins running side by side along a leaf; venation in a grass leaf; as opposed to palmate venation.

Resistant Plant

A plant with qualities that hinder the development of a given pathogen even when conditions favorable for disease development exist.


The amount of pesticide deemed safe and permitted by law on an agricultural product.


a substance used to attract destructive animals, usually used with a killing agent


The thin, noncellular, dead outermost covering layer of the epidermis (skin).

Foliar sprays

Pesticides which are applied on the stems, leaves, needles or blades of a plant

Translocated Herbicide

Chemical taken up by leaves or other plant parts and carried (translocated) to other plant parts, such as roots, stems, etc., where it kills plant tissue and the entire plant, e.g. 2,4-D, 2,4,5-T, and ammonium sulfamate.


The seeping of chemicals or moisture though the soil.


An organism living on or within and obtaining food from another living organism.


a plant stem that grows underground and often sends out roots and shoots from its nodes.

Acute Toxicity

That which is manifest on short exposure such as a single oral intake of a pesticide.

Biennial plant

A plant that requires two growing seasons to produce flower and fruit, after which it dies. Many biennials produce fleshy tap roots in the first year.


A waxy substance covering the leaves and stems of most plants, forming the cuticle.


The form in which the pesticide is offered for sale to the user, as an emulsifiable concentrate, wettable powder, granule, dust, oil solution, etc.


Localized spot of diseased tissue.


Any organism capable of causing disease.

Weed Control

The process of limiting weed infestations so that crops can be grown profitably or other operations can be conducted efficiently.


43,560 square feet (4,047 m2) or an area of land about 209 feet (63.6 m) by 209 feet

Complete metamorphosis

Metamorphosis in which the insect develops by four distinct stages: egg, larva, pupa, adult.

Emulsifiable concentrate

A liquid capable of forming a spray or dip emulsion when mixed with water; usually consisting of water insoluble pesticide chemicals plus surfactants, with or without solvents.


The larval state of scarab beetles, C-shaped with well-developed heads; usually the most damaging stage to plants.


Any of a large class (Insecta) of Arthropods that as adults have three body segments and three pairs of legs.


Death of a plant cell or tissues; generally obvious as change in color or dried appearance or spots, as in leaves.


Application of an herbicide before weed emerges from the soil.


Tiny, bleached spots on leaves; a symptom typically produced by mites, aphids, and similar insects.

Annual weed

Plant that naturally completes its life cycle within one year from germination to seed production and death.


material added to pesticide mixture to make the active ingredient more effective (e.g., wetting agent, spreader, adhesive, emulsifying agent, penetrant).


A chemical formulation containing a high percentage of active ingredient. For practical purposes, and formulation containing an excess of 20% of the active ingredient on a weight basis.


The sum of the surrounding factors that will affect a plant (or animal), including moisture, soil properties, temperatures, drainage, etc.


The natural environment or locale of a living organism.


A chemical used to kill or control insects.


Botanically, any plant of the family gramineae. Generally, in grassland agriculture, the term “grass” does not include the cereals usually harvested for grain, but does include the forage species of legumes, often grown in association with grasses.

Active Ingredient

An ingredient which will prevent, destroy, repel or mitigate insects, fungi, rodents, weeds, etc. The actual toxic agent in a formulation, e.g. technical pesticides.


The mass of thread-like elements (hyphae) forming a major portion of the vegetative growth of many fungi.

Powdery Mildew

Superficial white or grayish-white fungal growth on the surface of leaves and shoots caused by a specific group of fungi.

Spray Drift

The movement of airborne spray particles from the intended area of application.


A substance easily changed from a liquid to a gas, e.g. ether and gasoline and to a lesser degree, 2, 4-D ester.

Compatible chemicals

Chemicals that can be mixed together while still maintaining a satisfactory physical state that does not decrease effectiveness against targeted pests.


Study of the relationships between living organisms and their environment.


A living plant or animal that is so small that it can be seen only through a microscope.


An unwanted organism (animal, plant, bacteria, fungus, virus, etc.)


The movement of a material from one plant part to another, occurs primarily through veins.

Biological control

controlling pests by means of living organisms, such as predators, parasites, and disease-producing organisms


A type of pesticide which causes the leaves of a plant to drop off.


Insect droppings.


Any agent or chemical for use in destroying, controlling, or preventing weeds.


The ability of a chemical or pesticide to remain active in the soil for an extended period of time.


Diseases characterized by reddish-orange to reddish-brown pustules on leaves or stems caused by a specific group of fungi.

Oral Toxicity

A poisoning resulting from oral intake of a pesticide.

Broad-spectrum pesticides

general purpose or with a wide range of uses. Such pesticides are effective when several different pests are a problem.


The process by which pesticides are reduced to less complex inactive forms.


A sticky, sugary substance secreted by certain insects (including aphids, white flies, mealybugs, lace bugs, and scales) while feeding on plant tissue.


the entrance of a chemical into a plant, microorganism, or soil particle


Ability of a pesticide to mix with other components of a formulation without separation or reaction impairing its pesticide performance; mixing together without reduced pesticide activity of one or more pesticides. e.g.: DDT and Lindane in sprays; DDT and BHC in dusts.


A finely ground, dry mixture containing a small amount of pesticide and an inert carrier such as talc or clay. Dust particles are of many different sizes.


The sprouting of a seed when environmental conditions are suitable.


Any pests found in an area or place where they are not desirable.


Foliar symptom characterized by irregular pattern of indistinct light and dark areas.


A microscopic structure, usually one-celled, which is capable of germinating to produce a new plant.


a plant that produces a seed with one cotyledon. Characterized by narrow, parallel-veined leaves, flower parts in 3’s or multiples of 3 fibrous root system, no cambium tissue, embryos having only one cotyledon, and other characteristics, e.g. grasses.


A process by which carbon dioxide and water are converted to sugars and oxygen in the presence of chlorophyll, utilizing the energy of light.


Leaf tissue between veins eaten, leaving only the veins and the upper or lower leaf surface.


Mottling of green plant tissue, resulting from of a lack of chlorophyll through its failure to develop. A symptom of many viral diseases.


The movement of material (spray mist or dust) outside the intended area during or shortly after application.


Outgrowth or swelling of unorganized plant cells; may be caused by certain disease-causing organisms or insects.


The establishment of a parasite within a host.


Small, upright, leafy plants that commonly grow on decaying matter of soil under moist, sheltered, shaded, and acidic conditions.


plant and toxic/poisonous, a substance that is poisonous to plants.


The relative capability of a substance to dissolve in a liquid.


The relative health of a plant.


A lesion on stems, branch or twig characterized by dead tissue, often sunken in the center with raised growth around the edges.


Plant stage in which growth and physiological activities have temporarily ceased or are reduced to a minimum, evidenced in many plants by loss of leaves.