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 3x to 6x 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.
Triclopyr is an organic compound in the pyridine group that is used as a systemic foliar herbicide and fungicide.
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.
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."
Sclerotinia sclerotiorum is a plant pathogenic fungus and can cause a disease called white mold if conditions are conducive. S. sclerotiorum can also be known as cottony rot, watery soft rot, stem rot, drop, crown rot and blossom blight. A key characteristic of this pathogen is its ability to produce black resting structures known as sclerotia and white fuzzy growths of mycelium on the plant it infects. These sclerotia give rise to a fruiting body in the spring that produces spores in a sac which is why fungi in this class are called sac fungi (Ascomycota). This pathogen can occur on many continents and has a wide host range of plants. When S. sclerotiorum is onset in the field by favorable environmental conditions, losses can be great and control measures should be considered.
Mecoprop is a common general use herbicide found in many household weed killers and "weed-and-feed" type lawn fertilizers. It is primarily used to control broadleaf weeds. It is often used in combination with other chemically related herbicides such as 2,4-D, dicamba, and MCPA, which mimic the plant hormone IAA (auxin) and kill most broadleaf weeds by causing uncontrolled growth.
Metsulfuron-methyl is an organic compound classified as a sulfonylurea herbicide, which kills broadleaf weeds and some annual grasses. It is a systemic compound with foliar and soil activity, that inhibits cell division in shoots and roots. It has residual activity in soils, allowing it to be used infrequently but requiring up to 22 months before planting certain crops. It has very low toxicity to mammals, birds, fish, and insects but is a moderate eye irritant.
Trifluralin is a commonly used pre-emergence selective herbicide. 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. Introduced in 1964, Trifluralin was the first organofluorine compound used as an agrochemical.
Organic beans are produced and processed without the use of synthetic fertilizers and pesticides. In 2008, over 2,600,000 acres (11,000 km2) of cropland were certified organic in the United States. Dry beans, snap beans, and soybeans were grown on 16,000 acres (65 km2), 5,200 acres (21 km2), and 98,000 acres (400 km2), respectively.
2,4-Dichlorophenoxyacetic acid is an organic compound with the chemical formula Cl2C6H3OCH2CO2H. It is usually referred to by its ISO common name 2,4-D. It is a systemic herbicide that kills most broadleaf weeds by causing uncontrolled growth, but most grasses such as cereals, lawn turf, and grassland are relatively unaffected.
Acifluorfen is the ISO common name for an organic compound used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase which is necessary for chlorophyll synthesis. Soybeans naturally have a high tolerance to acifluorfen and its salts, via metabolic disposal by glutathione S-transferase. It is effective against broadleaf weeds and grasses and is used agriculturally on fields growing soybeans, peanuts, peas, and rice.
4-Hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors are a class of herbicides that prevent growth in plants by blocking 4-Hydroxyphenylpyruvate dioxygenase, an enzyme in plants that breaks down the amino acid tyrosine into molecules that are then used by plants to create other molecules that plants need. This process of breakdown, or catabolism, and making new molecules from the results, or biosynthesis, is something all living things do. HPPD inhibitors were first brought to market in 1980, although their mechanism of action was not understood until the late 1990s. They were originally used primarily in Japan in rice production, but since the late 1990s have been used in Europe and North America for corn, soybeans, and cereals, and since the 2000s have become more important as weeds have become resistant to glyphosate and other herbicides. Genetically modified crops are under development that include resistance to HPPD inhibitors. There is a pharmaceutical drug on the market, nitisinone, that was originally under development as an herbicide as a member of this class and is used to treat an orphan disease, type I tyrosinemia.
Aminocyclopyrachlor is a selective, low-toxicity herbicide that provides pre- and post-emergent control of broadleaf weeds, woody species, vines and grasses on several non-food use sites, such as 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. This causes undifferentiated cell division and elongation.
The Enlist Weed Control System is an agricultural system that includes seeds for genetically modified crops that are resistant to Enlist and the Enlist herbicide; spraying the herbicide will kill weeds but not the resulting crop. The system was developed by Dow AgroSciences, part of Dow Chemical Company. In October 2014 the system was registered for restricted use in Illinois, Indiana, Iowa, Ohio, South Dakota and Wisconsin by the US Environmental Protection Agency. In 2013, the system was approved by Canada for the same uses.
Fluxapyroxad is a broad-spectrum pyrazole-carboxamide fungicide used on a large variety of commercial crops. It stunts fungus growth by inhibiting the succinate dehydrogenase (SQR) enzyme. Application of fluxapyroxad helps prevent many wilts and other fungal infections from taking hold. As with other systemic pesticides that have a long chemical half-life, there are concerns about keeping fluxapyroxad out of the groundwater, especially when combined with pyraclostrobin. There is also concern that some fungi may develop resistance to fluxapyroxad.
Cyproconazole is an agricultural fungicide of the class of azoles, used on cereal crops, coffee, sugar beet, fruit trees and grapes, and peanuts, on sod farms and golf course turf and on wood as a preservative. It has been used against powdery mildew, rust on cereals and apple scab, and applied by air or on the ground or by chemigation.
Glyphosate-based herbicides are usually made of a glyphosate salt that is combined with other ingredients that are needed to stabilize the herbicide formula and allow penetration into plants. The glyphosate-based herbicide Roundup was first developed by Monsanto in the 1970s. It is used most heavily on corn, soy, and cotton crops that have been genetically modified to be resistant to the herbicide. Some products include two active ingredients, such as Enlist Duo which includes 2,4-D as well as glyphosate. As of 2010, more than 750 glyphosate products were on the market. The names of inert ingredients used in glyphosate formulations are usually not listed on the product labels.
Oxyfluorfen is a chemical compound used as an herbicide. It is manufactured by Dow AgroSciences, Adama Agricultural Solutions and 4Farmers under the trade names Goal, Galigan, and Oxyfluorfen 240. Oxyfluorfen is used to control broadleaf and grassy weeds in a variety of nut, tree fruit, vine, and field crops, especially wine grapes and almonds. It is also used for residential weed control.
Fomesafen is the ISO common name for an organic compound used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase (PPO) which is necessary for chlorophyll synthesis. Soybeans naturally have a high tolerance to fomesafen, via metabolic disposal by glutathione S-transferase. As a result, soy is the most common crop treated with fomesafen, followed by other beans and a few other crop types. It is not safe for maize/corn or other Poaceae.
