(Science: chemical) a chemical used to kill or control the growth of plants. Some herbicides (such as synthetic auxins and triazine) selectively kill broad-leaved plants while leaving grass-leaved plants (i.e., cereal crops) unharmed.
Other herbicides, such as paraquat, kill all plants. Herbicide use has dramatically increased crop Yield worldwide but has caused serious environmental problems, polluting soil and water and causing health hazards for humans and animals.
See: pesticide. a chemical agent that destroys plants or inhibits their growth.Chemicals that have been specifically made to kill plants, or more importantly specific plants. They may be used in a certain crop to eliminate competition for resources in the area and allow the crop to grow to its potential.