Herbicides, also commonly known as weed killers, are substances used to control undesired plants, also known as weeds. Selective herbicides control specific weed species while leaving the desired crop relatively unharmed, while non-selective herbicides kill plants indiscriminately. The combined effects of herbicides, nitrogen fertilizer, and improved cultivars has increased yields of major crops by three to six times from 1900 to 2000.
Glyphosate is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSP). It is used to kill weeds, especially annual broadleaf weeds and grasses that compete with crops. Its herbicidal effectiveness was discovered by Monsanto chemist John E. Franz in 1970. Monsanto brought it to market for agricultural use in 1974 under the trade name Roundup. Monsanto's last commercially relevant United States patent expired in 2000.
Paraquat (trivial name; ), or N,N′-dimethyl-4,4′-bipyridinium dichloride (systematic name), also known as methyl viologen, is a toxic organic compound with the chemical formula [(C6H7N)2]Cl2. It is classified as a viologen, a family of redox-active heterocycles of similar structure. This salt is one of the most widely used herbicides worldwide. It is quick-acting and non-selective, killing green plant tissue on contact.
Alachlor is an herbicide from the chloroacetanilide family. It is an odorless, white solid. The greatest use of alachlor is for control of annual grasses and broadleaf weeds in crops. Use of alachlor is illegal in the European Union and no products containing alachlor are currently registered in the United States.
Chlortoluron, chlorotoluron and CTU are the common names for an organic compound of the phenylurea class of herbicides used to control broadleaf and annual grass weeds in cereal crops.
Dicamba is a selective systemic herbicide first registered in 1967. Brand names for formulations of this herbicide include Dianat, Banvel, Diablo, Oracle and Vanquish. This chemical compound is a chlorinated derivative of o-anisic acid. It has been described as a "widely used, low-cost, environmentally friendly herbicide that does not persist in soils and shows little or no toxicity to wildlife and humans."
Trifluralin is a common pre-emergent selective herbicide, a dinitroaniline. With about 14 million pounds (6,400 t) used in the United States in 2001, and 3–7 million pounds (1,400–3,200 t) in 2012, it is one of the most widely used herbicides. Trifluralin is also used in Australia, and New Zealand, previously in the EU. Introduced in 1964, Trifluralin was the first organofluorine compound used as an agrochemical.
Mesotrione is a selective herbicide used mainly in maize crops. It is a synthetic compound inspired by the natural substance leptospermone found in the bottlebrush tree Callistemon citrinus. It inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) and is sold under brand names including Callisto and Tenacity. It was first marketed by Syngenta in 2001.
Benfluralin is an herbicide of the dinitroaniline class. The mechanism of action of benfluralin involves pre-emergent inhibition of mitosis, root and shoot development, same as trifluralin, from which benfluralin was developed in 1963.
Aminocyclopyrachlor (AMCP) is a selective, low-toxicity, auxin-mimicking herbicide that provides pre- and post-emergent control of broadleaf weeds on several non-food use sites including rights of way, wildlife management areas, recreational areas, turf/lawns, golf courses and sod farms. It was conditionally registered as Imprelis by DuPont in August 2010, and first used in Fall 2010. The chemical is a systemic herbicide and acts by disrupting gene expression. Aminocyclopyrachlor belongs to the pyrimidine carboxylic acid chemical family and mimics auxin which is a growth-regulating hormone in dicots including broadleaf terrestrial plants. This causes undifferentiated cell division and elongation, with resulting appearance characteristic of auxin herbicide damage such as leaf twisting and curling.
Fluazifop is the common name used by the ISO for an organic compound that is used as a selective herbicide. The active ingredient is the 2R enantiomer at its chiral centre and this material is known as fluazifop-P when used in that form. More commonly, it is sold as its butyl ester, fluazifop-P butyl with the brand name Fusilade.
Indaziflam is a preemergent herbicide especially for grass control in tree and bush crops.
Tribenuron in the form of tribenuron-methyl is a sulfonylurea herbicide. Its mode of action is the inhibition of acetolactate synthase, group 2 of the Herbicide Resistance Action Committee's classification scheme.
Chlorsulfuron is an ALS inhibitor herbicide, and is a sulfonylurea compound. It was discovered by George Levitt in February 1976 while working at DuPont, which was the patent assignee.
Prosulfocarb is a pre-emergent herbicide used agriculturally in Australia, the EU, Japan, New Zealand,, Morocco and Iran, for control of annual ryegrass and toad rush in wheat and barley crops. It was introduced to the EU in 1988 and is rapidly growing in use, with sales increasing by over 500% in France since 2008.
The Herbicide Resistance Action Committee (HRAC) classifies herbicides by their mode of action (MoA) to provide a uniform way for farmers and growers to identify the agents they use and better manage pesticide resistance around the world. It is run by CropLife International in conjunction with the Weed Science Society of America (WSSA).
Nitralin is a selective pre-emergent dinitroaniline herbicide that is closely related to trifluralin, and released two years later in 1966. Today it is largely obsolete. It was used in the USA, France and Australia to control annual grasses and broad-leaved weeds, and was applied on vines, crops and turf.
Profluralin is a dinitroaniline herbicide used preëmergently to control annual grasses and broadleaf weeds, in cotton, soybeans, peanuts, sunflower, cabbage, cauliflower, tomato and others. Profluralin has largely fallen out of use. It rose out of the related, still in common use, trifluralin.
Ethalfluralin is a herbicide. It is a preëmergent dinitroaniline developed from trifluralin, used to control annual grasses and broad-leaved weeds. It was synthesised in 1971, first sold in Turkey in 1975, the United States in 1983. It is used on soybeans, peanuts, potatoes, and as of 2023, is the first conventional herbicide the EPA permits on hemp, as ethalfluralin leaves no residue in the plant. Ethalfluralin is not used domestically.
Dinitramine is a preëmergent dinitroaniline herbicide incorporated into soil to control weeds for months after. It is no longer approved in the U.S.A., and is not in the European Union, though in Iran it has been used to control annual grasses and broadleaf weeds in cotton and soybeans, as it was in the U.S. as of 1975, where it was also used on sunflower.
