A chemical that will kill or inhibit the growth of weeds, a herbicide. Contact - a weed-killer that kills only that part of the plant from which it comes into contact; Hormone - a weed-killer that is similar to substances produced naturally by the plant which regulate the growth of the plant; Residual - a weed-killer that is applied to the soil where it persists for some time, killing weeds as they germinate; Selective - a weed-killer which, used correctly, causes no injury to the crop or no injury of any economic importance; Total - non-selective weed-killer. A weed-killer which is used to kill all vegetation as opposed to one used selectively; Translocated - a weed-killer which is absorbed by the plant and moves about within the plant before killing it.

a chemical agent that destroys plants or inhibits their growth

See herbicide