Chemical methods of controlling pests is by the application of pesticides, weedicides and fertilizers. Their application is intended to kill a pest or a weed. Though the pesticide kills the unwanted foreign element they leave a layer of poison on the outer surface of the plant which may be hazardous to the plant but even more hazardous to the organisms which consume the plant without proper cleaning. These pesticides may also get mixed with water and be a threat to aquatic life.
