Herbicide

A herbicide is a pesticide used to kill unwanted plants. Selective herbicides kill certain targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often based on plant hormones. Herbicides used to clear waste ground are nonselective and kill every plant with which they come into contact. Some plants produce natural herbicides, such as the genus Juglans (walnuts).

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Prior to the widespread use of chemical herbicides, cultural controls, such as altering soil pH, salinity, or fertility levels, were used to control weeds.

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The first widely used herbicide was 2,4-dichlorophenoxyacetic acid, often abbreviated 2,4-D. It was developed by a British team during World War II and first saw widespread production and use in the late 1940s. It is easy and inexpensive to manufacture, and kills many broadleaf plants while leaving grasses unaffected. 2,4-D's low cost has led to continued usage today and it remains the most commonly used herbicide in the world. Like other acid herbicides, current formulations utilize either an amine salt (usually trimethyl amine) or one of many esters (ester) of the base compound. These are easier to handle than the acid.

Pesticide: A pesticide is a chemical, or sometimes biological agent such as a virus or bacteria, used to control, to repel, to attract, or to kill pests, which are organisms, including insects, weeds, birds, mammals, fish, and microbes, that compete with humans for food, destroy property, spread disease, or ar...

Plant: Land plants (embryophytes)Non-vascular plants (bryophytes)Hepaticophyta - liverwortsAnthocerotophyta - hornwortsBryophyta - mossesVascular plants (tracheophytes)Lycopodiophyta - clubmossesEquisetophyta - horsetailsPteridophyta - "true" fernsPsilotophyta - whisk fernsOphioglossophyta - adderstonguesS...

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