herbicide summary

Written and fact-checked by The Editors of Encyclopaedia Britannica

Below is the article summary. For the full article, see herbicide.

herbicide, Agent, usually chemical, for killing or inhibiting the growth of unwanted plants such as weeds or invasive species. Modern herbicides are put into 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, and paraquat) kill only the plant organs with which they are in contact. Translocated herbicides (e.g., amitrole, picloram, and 2,4-D) are effective against roots or other organs, to which they are transported from aboveground treated surfaces (soil). Herbicides can be synthetic (human-made) or naturally occurring, the latter being more commonly used in organic farming. See also defoliant.

Novartis AG Summary

Novartis AG, Swiss company that is one of the world’s largest manufacturers of pharmaceuticals. It was formed in 1997 from the merger of two major Swiss drug companies, Ciba-Geigy AG and Sandoz AG. Novartis is headquartered in Basel. Ciba-Geigy originated in the merger of two smaller Swiss firms,