Weed Management Handbook

A plant that grows in water. The three kinds are: Submergent grows beneath the surface; Emergent grows above the water (cattails and water lilies); and Floaters such as water hyacinth.

A first-aid treatment to counteract poisoning.

Opposing action of different chemicals such that the action of one is impaired or the total effect is less than that of one component used separately.

A plant that completes its life cycle in 1 year; i.e., germinates from seed, produces seed, and dies in the same season. Examples include pigweed, ragweed, mustard, foxtail, and crabgrass. A winter annual is one that germinates in the fall, lives over winter, then flowers and seeds the following spring and summer. Pennyroyal, hedge mustard, and peppergrass are winter annuals. (Also see Winter Annual.)

A surface-active additive to a herbicide having a negative charge. Not commonly used with herbicides.

To mix continuously.

Adherence of a substance to a surface.

Any substance in a herbicide formulation that enhances the effectiveness of the herbicide.

The amount of a substance, as a single dose, to cause poisoning in a test animal.

Dosage required to kill 50% of test animals given a single oral dose in toxicity studies.