HRAC Classification
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HRAC Classification
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). Resistance overview A weed that develops resistance to one herbicide typically has resistance to other herbicides with the same mode of action (MoA), so herbicides with different MoAs, or different resistance groups, are needed. Preventative weed resistance management rotates herbicide types to prevent selective breeding of resistance to the same mode of action. By rotating MoAs, successive generations gain no advantage from any resistant mutations of the last generation. ''Cross-resistant'' and ''multiply resistant'' weeds resist multiple MoAs, and are particularly difficult to control. There is limited evidence of resistance undoing other res ...
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Herbicide
Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page for EPA reports on pesticide use ihere Selective herbicides control specific weed species while leaving the desired crop relatively unharmed, while non-selective herbicides (sometimes called "total weed killers") kill plants indiscriminately. The combined effects of herbicides, nitrogen fertilizer, and improved cultivars has increased yields (per acre) of major crops by three to six times from 1900 to 2000. In the United States in 2012, about 91% of all herbicide usage, was determined by weight applied, in agriculture. In 2012, world pesticide expenditures totaled nearly US$24.7 billion; herbicides were about 44% of those sales and constituted the biggest portion, followed by insecticides, fungicides, and fumigants. Herbicide is also used ...
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:Category:Group 2 Herbicides
Group 2 is a category of the HRAC classification system by herbicidal mode of action. It is equivalent to Group B (Australia) and Group B (Global). These herbicides work by inhibition of acetolactate synthase The acetolactate synthase (ALS) enzyme (also known as acetohydroxy acid or acetohydroxyacid synthase, abbr. AHAS) is a protein found in plants and micro-organisms. ALS catalyzes the first step in the synthesis of the branched-chain amino acids .... Herbicides by numeric HRAC ...
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Propanil
Propanil is a widely used contact herbicide. With an estimated use of about 8 million pounds in 2001, it is one of the more widely used herbicides in the United States. Propanil is said to be in use in approximately 400,000 acres of rice production each year. Propanil was introduced in 1960. It is also used in India and Australia.PPDB
retrieved 2-2025-March


Mode of action

The principal mode of propanil's herbicidal action against weeds is inhibition of their photosynthesis and CO2 fixation. Plants photosynthesize in two stages. In stage I photosynthetic reactions capture sunlight energy and yield molecules with high energy content. In stage II these molecules react to capture CO2, yielding carbohydrate precursors. In the stage I reaction a chlorophyll molecule absorbs one photon (light) and l ...
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Simazine
Simazine is an herbicide of the triazine class. The compound is used to control broad-leaved weeds and annual grasses. Preparation Simazine may be prepared from cyanuric chloride and a concentrated solution of ethyl amine (at least 50 percent by number) in water. The reaction is highly exothermic and is therefore best carried out below 10 °C. Cyanuric chloride decomposes at high temperatures into hydrogen chloride and hydrogen cyanide, both of which are highly toxic by inhalation. Properties and uses Simazine is an off-white crystalline compound which is sparingly soluble in water. It is a member of the triazine-derivative herbicides, and was widely used as a residual non-selective herbicide, but is now banned in European Union states. Like atrazine, a related triazine herbicide, it acts by inhibiting photosynthesis. It remains active in the soil for two to seven months or longer after application. See also * Atrazine Atrazine ( ) is a Organochlorine compo ...
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Atrazine
Atrazine ( ) is a Organochlorine compound, chlorinated herbicide of the triazine class. It is used to prevent pre-emergence broadleaf weeds in crops such as maize (corn), soybean and sugarcane and on turf, such as golf courses and residential lawns. Atrazine's primary manufacturer is Syngenta and it is one of the most widely used herbicides in the United States, Canadian, and Australian agriculture. Its use was banned in the European Union in 2004, when the EU found groundwater levels exceeding the limits set by regulators, and Syngenta could not show that this could be prevented nor that these levels were safe.European Commission.2004/248/EC: Commission Decision of 10 March 2004 concerning the non-inclusion of atrazine in Annex I to Council Directive 91/414/EEC and the withdrawal of authorisations for plant protection products containing this active substance (Text with EEA relevance) (notified under document number C(2004) 731) Decision 2004/248/EC - Official Journal L 078, Decis ...
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:Category:Group 5 Herbicides
Group 5 is a category of the HRAC classification system by herbicidal mode of action In pharmacology and biochemistry, mode of action (MoA) describes a functional or anatomical change, resulting from the exposure of a living organism to a substance. In comparison, a mechanism of action (MOA) describes such changes at the molecul .... It is equivalent to Group C (Australia) and Groups C1 and C2 (Global). Note, the classification was changed slightly. Group C (Aus) and Group C2 (Global) herbicides may actually be Group 7. Herbicides by numeric HRAC ...
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Sulfonylurea
Sulfonylureas or sulphonylureas are a class of organic compounds used in medicine and agriculture. The functional group consists of a sulfonyl group (-S(=O)2) with its sulphur atom bonded to a nitrogen atom of a ureylene group (N,N-dehydrourea, a dehydrogenated derivative of urea). The side chains R1 and R2 distinguish various sulfonylureas. Sulfonylureas are the most widely used herbicide. Agricultural uses Many sulfonylureas are also used as herbicides, because they can interfere with plant biosynthesis of certain amino acids. As herbicides sulfonylureas function by interfering with biosynthesis of the amino acids valine, isoleucine, and leucine, specifically via acetolactate synthase inhibition. Compounds in this class include amidosulfuron, azimsulfuron, bensulfuron-methyl, chlorimuron-ethyl, chlorsulfuron, ethametsulfuron-methyl, cinosulfuron, ethoxysulfuron, flazasulfuron, flupyrsulfuron-methyl-sodium, imazosulfuron, metsulfuron-methyl, nicosulfuron, oxasulfuro ...
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Imidazolinone
Imidazolinones or imidazolones are a family of heterocyclic compounds, the parents of which have the formula OC(NH)2(CH)2. Two isomers are possible, depending on the location of the carbonyl (CO) group. The NH groups are nonadjacent. A common route to imidazol-2-ones involves condensation of ureas and acyloins. Some are of interest in the pharmaceuticals.{{cite journal, journal=Chemistry of Heterocyclic Compounds, year=2015, volume=51, pages=395–420 , title=Methods for the synthesis of 1-substituted 1H-imidazol-2(3H)-ones, first1=Maria M., last1=Antonova, first2=Vladimir V., last2=Baranov, first3=Angelina N., last3=Kravchenko, issue=5 , doi=10.1007/s10593-015-1716-3 4-Imidazolones arise from the condensation of amidines with 1,2-dicarbonyls such as glyoxal Glyoxal is an organic compound with the chemical formula OCHCHO. It is the smallest dialdehyde (a compound with two aldehyde groups). It is a crystalline solid, white at low temperatures and yellow near the melting point ...
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