Agent, usually chemical, for killing or inhibiting the growth of unwanted plants (weeds). Modern weed killers are put in two categories, selective (affecting specific plant species) and nonselective (affecting plants generally). These in turn are classified as foliage-applied and soil herbicides. Contact herbicides (e.g., sulfuric acid, diquat, paraquat) kill only the plant organs with which they are in contact. Translocated herbicides (e.g., amitrole, picloram, 2,4-D) are effective against roots or other organs, to which they are transported from aboveground treated surfaces (soil). See also defoliant.

This entry comes from Encyclopædia Britannica Concise.
For the full entry on herbicide, visit Britannica.com.

Seen & Heard

What made you look up herbicide? Please tell us what you were reading, watching or discussing that led you here.

Get Our Free Apps
Voice Search, Favorites,
Word of the Day, and More
Join Us on FB & Twitter
Get the Word of the Day and More