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Underground rootlike stem that produces roots and leafy shoots.

The basal or early leaves of a plant, before bolting.

The reservoir of viable seeds present in the soil.

Early stages of growth of crop plants or weeds, within a few days or weeks after seed germination and emergence.

A chemical that is more toxic to some plant species than to others (may be a function of dosage or mode of application).

Water that does not contain those minerals that prevent free lathering when soap is added (see Hard Water).

Placement of the herbicide beneath the soil surface with minimum mixing or stirring of the soil, as with an injection blade, knife, or tine.

Placement of the herbicide in a discrete horizontal zone under a lifted or tilled layer of soil.

Length of time that a herbicide application on or in soil remains effective.

A herbicide that prevents the growth of plants when present in the soil. Soil residual effects may be temporary or relatively permanent.

The amount of a substance that will dissolve in a given amount of liquid.

A dry herbicide formulation that is soluble in the carrier liquid.

A liquid such as water or oil used to dissolve other material such as herbicides.

Application of sprays to localized or restricted areas.

The movement of airborne spray particles from the intended contact area to other areas.

A substance used to improve the wetting, spreading, or possibly the adhesive properties of a herbicide spray solution.

Bolt-A seedstalk forms following development of rosette.


A seedbed developed by tilling the soil before crop planting to stimulate weed emergence, but where the tools used to remove the weeds are applied after the crop is planted.

Aboveground runners or slender stems that develop roots and shoots and new plants at the tips or nodes, as in the strawberry plant.

Retardation of growth and development of weeds or crops.

Results produced in test animals by long-term exposure to repeated doses or concentrations of a substance.

Reduction, but not elimination, of weed population.

Due to surface molecular forces, a drop of liquid tends to form an apparent membrane that causes it to ball up rather than to spread as a film.

A material used in formulations to impart emulsifiability, spreading, wetting, dispersibility, or other surface-modifying properties.

A liquid or gas in which very fine solid particles are dispersed but not dissolved.

Complementary action of different chemicals so that the total effect is greater than the sum of the independent effects.

A compound that moves freely within a plant so that application to one area will result in movement to all areas of the plant to exert its effect.

A compound causing congenital malformations in the fetus (birth defects).

The amount of pesticide chemical allowed by law to be in or on a plant or animal product sold for human consumption.

Capable of withstanding effects. For example, grass is tolerant of 2,4-D to the extent that this herbicide can be used selectively to control broadleaf weeds without killing the grass.

Treatment of a localized surface site such as a single leaf blade, petiole, or growing point.

Poisonous; injurious to animals and plants through contact or systemic action.

Transfer of sugars or other materials such as 2,4-D from one part to another in plants. (See Systemic.)

The movement of vapors from the area of application to other areas.

A compound is volatile when it evaporates or vaporizes (changes from liquid to a gas) at ordinary temperatures on exposure to the air.

A two-phase concentrate that contains solid herbicide suspended in liquid that is capable of suspension in water.

A finely ground herbicide powder that will dissolve in water.

A plant growing where it is not desired. Any plant that is a nuisance, hazard, or causes injury to humans, animals, or the desired crop.

The process of limiting weed infestations or killing weeds for aesthetic, economic, public health, or other reasons.

The elimination of all live plants, plant parts, and seeds of a weed from a site.