HRAC classification

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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. [1] [2] It is run by CropLife International [3] in conjunction with the Weed Science Society of America (WSSA). [4]

Contents

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. [5] Cross-resistant and multiply resistant weeds resist multiple MoAs, [6] and are particularly difficult to control.

There is limited evidence of resistance undoing other resistances. For example, prosulfocarb and trifluralin: their inverse mechanisms of resistance contradict, and so by evolving to one the weed loses resistance to the other, at least by metabolic resistance. Prosulfocarb requires a weed to metabolise it very slowly to survive; trifluralin on the other hand must be metabolised quickly before it can deal damage to the weed. [7]

Naming types

The HRAC give a letter based class to each active constituent herbicide. The Australian HRAC code is separately assigned, though is often the same as the global code. In 2021, alternative numeric classes were added, to make codes globally more consistent. This set of classification changes also added or moved a few herbicides that had been misclassified, and reduced regional concerns that using the English alphabet could be an impediment for international growers. [5]

Herbicides that act through multiple modes have multiple classifications, corresponding to each MoA. [8] For example, Quinmerac is classified as Group 4/29 (O/L) because it is both an Auxin mimic (Group 4 or O) and inhibits cellulose synthesis (Group 29 or L). [9]

Groups

HRAC Classification Groups [10] [9]
HRAC (AUS)HRAC (Global)HRAC (Numeric)Mode of actionExample herbicidesExample chemical families
AA1Inhibits acetyl coa carboxylase Haloxyfop-methyl, Clethodim, Sethoxydim, Pinoxaden Aryloxyphenoxy-propionates, Cyclohexanediones, Phenylpyrazolines
BB2Inhibits acetolactate synthase Imazamox, Chlorsulfuron, Pyrithiobac-sodium, Florasulam Imidazolinones, Pyrimidinyl benzoates, Sulfonylureas, Triazolopyrimidines
CC1 / C25Inhibits photosynthesis at PSII - serine 264 binders Atrazine, Simazine, Propanil, Amicarbazone, Bromacil, Diuron Triazines, Amides, Phenlcarbamates, Pyridazinones, Triazinones, Triazolinones, Uracil, Ureas
CC36Inhibits photosynthesis at PSII - histidine 215 binders/uncouplers Bentazon, Bromoxynil, Ioxynil Benzothiadiazinones, Nitriles
-C27 Isoproturon [11] Urea
DK13inhibits microtubule assembly Trifluralin, Pendimethalin, Propyzamide, Dithiopyr [10] , butamiphos, chlorthal-dimethyl [12] Dinitroanilines, Benzoic acids, Pyridines, [10] Phosphoroamidates, Benzoic acids [12]
EK223Inhibits microtubule organisation Carbetamide Carbamates
FF112Inhibits phytoene desaturase Diflufenican, Norflurazon Phenyl ethers, N-Phenyl heterocycles
GE14Inhibits protoporphyrinogen oxidase Butafenacil, Carfentrazone-ethyl, Oxyfluorfen N-Phenyl-imides. Diphenyl ethers, N-Phenyl-oxadiazolones, Phenylpyrazoles
HF227Inhibits hydroxyphenyl pyruvate dioxygenase Isoxaflutole, Pyrasulfotole, Mesotrione Soxazoles, Pyrazoles, Triketones
IO4 Auxin mimic Dicamba, Halauxifen, Picloram, 2,4-D, MCPA, Triclopyr, Quinclorac 6-Arylpicolinates, 6-Chloropicolinates, Benzoates, Phenoxy-carboxylates, Pyridyloxy-carboxylates, Quinoline-carboxylates
JK3 / N15Inhibits very long chain fatty acid synthesis Prosulfocarb, Ethofumesate Thiocarbamates, Benzofurans
J-Unknown Bensulide, Delapon Chlorocarbonic acids
KK315Inhibits very long chain fatty acid synthesis Metolachlor, Pyroxasulfone α-Chloroacetamides, Isoxazolines
K-Unknown Napropamide Acetamide
LD22PS I electron diversion Diquat, Paraquat Pyridinium
MG9Inhibits enolpyruvil shikimate phosphate synthase Glyphosate Glycine
NH10Inhibits glutamine-synthetase Glufosinate-ammonium Phosphinic acid
OL29inhibition of cellulose synthesis Isoxaben, Dichlobenil, Indaziflam Nitrile, Benzamide, Alkylazine
PP19Auxin transport inhibitor Naptalam Aryl-carboxylates
QF3 / F413Inhibits deoxy-d-xylulose phosphate synthesis Clomazone, Bixlozone Isoxazolidinone
Q--Unknown Amitrole Triazole
RI18Inhibits dihydropteroate synthase Asulam carbamate
--28Inhibition of dihydroorotate dehydrogenase Tetflupyrolimet
TQ / Z30Inhibits fatty acid thioesterase Cynmethylin Benzyl-ether
ZR31Inhibits serine-threonine protein phosphatase Endothal Other
ZZ-Unknown Flamprop-m, DSMA, MSMA, Pelargonic acid Arylaminopropionic acid, Others
-M24Uncouplers Dinosam Dinitrophenol
-S / F332Inhibition of Solanesyl Diphosphate Synthase Aclonifen Diphenyl ether
-T33Inhibition of Homogentisate Solanesyltransferase Cyclopyrimorate Phenoxypyridazine

See also

Related Research Articles

<span class="mw-page-title-main">Herbicide</span> Type of chemical used to kill unwanted plants

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.

<span class="mw-page-title-main">Pesticide resistance</span> Decreased effectiveness of a pesticide on a pest

Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens survive and pass on their acquired heritable changes traits to their offspring. If a pest has resistance then that will reduce the pesticide's efficacy – efficacy and resistance are inversely related.

<span class="mw-page-title-main">Paraquat</span> Chemical compound used as an herbicide

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.

<span class="mw-page-title-main">Glufosinate</span> Broad-spectrum herbicide

Glufosinate is a naturally occurring broad-spectrum herbicide produced by several species of Streptomyces soil bacteria. Glufosinate is a non-selective, contact herbicide, with some systemic action. Plants may also metabolize bialaphos and phosalacine, other naturally occurring herbicides, directly into glufosinate. The compound irreversibly inhibits glutamine synthetase, an enzyme necessary for the production of glutamine and for ammonia detoxification, giving it antibacterial, antifungal and herbicidal properties. Application of glufosinate to plants leads to reduced glutamine and elevated ammonia levels in tissues, halting photosynthesis and resulting in plant death.

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 molecular level.

<span class="mw-page-title-main">Pendimethalin</span> Chemical compound

Pendimethalin is an herbicide of the dinitroaniline class used premergently and postemergently to control annual grasses and certain broadleaf weeds. It inhibits cell division and cell elongation. Pendimethalin is a K1-group according to the Herbicide Resistance Action Committee (HRAC) classification and is approved in Europe, North America, South America, Africa, Asia and Oceania for different crops including cereals, corn, soybeans, rice, potato, legumes, fruits, vegetables, and nuts, plus lawns and ornamental plants.

<span class="mw-page-title-main">Dicamba</span> Chemical compound used as herbicide

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."

<span class="mw-page-title-main">Trifluralin</span> Weed control herbicide

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.

<span class="mw-page-title-main">Mesotrione</span> Chemical compound used as an herbicide

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.

<span class="mw-page-title-main">Quinclorac</span> Chemical compound

Quinclorac is an organic compound with the formula C9NH4Cl2CO2H. A colorless solid, it is soluble in hydrocarbons and alcohols. The compound is the carboxylic acid of 3,7-dichloroquinoline.

The Insecticide Resistance Action Committee (IRAC) was formed in 1984 and works as a specialist technical group of the industry association CropLife to be able to provide a coordinated industry response to prevent or delay the development of insecticide resistance in insect and mite pests. IRAC strives to facilitate communication and education on insecticide and traits resistance as well as to promote the development and facilitate the implementation of insecticide resistance management strategies.

<span class="mw-page-title-main">Fomesafen</span> PPOi herbicide

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.

<span class="mw-page-title-main">Fluazifop</span> ACCase herbicide, fop, anti-grass

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.

<span class="mw-page-title-main">Indaziflam</span> Preemergent herbicide discovered in 2009

Indaziflam is a preemergent herbicide especially for grass control in tree and bush crops.

<span class="mw-page-title-main">Butafenacil</span> Chemical compound

Butafenacil is the ISO common name for an organic compound of the pyrimidinedione chemical class used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase to control broadleaf and some grass weeds in crops including cereals and canola.

<span class="mw-page-title-main">Tribenuron</span> Chemical compound

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.

<span class="mw-page-title-main">Chlorsulfuron</span> ALS inhibitor herbicide

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.

<span class="mw-page-title-main">Metamitron</span> Herbicide

Metamitron is an organic compound used as a selective pre- and post-emergence herbicide in sugar beets. It is used in the European Union for weed suppression in sugar beets. Metamitron is marketed under the trade name Goltix by ADAMA in Europe, the United Kingdom, New Zealand, and South Africa.

<span class="mw-page-title-main">Prosulfocarb</span> Weed control herbicide

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.

References

  1. ↑ "Appendix 7. Classification of Herbicides According to Mode of Action" (PDF). University of Florida IFAS Extension . Retrieved November 20, 2024.
  2. ↑ "HRAC MoA Classification Update Webinar Training 6th May 2022". European Weed Research Society. Retrieved November 20, 2024.
  3. ↑ Sievernich, Bernd; Belvaux, Xavier; Hunt, Barrie (February 2024). "HRAC Europe – Partner on Weed Resistance Management". Julius-Kühn-Archiv. 478 (31). Bundesbehörden Und Einrichtungen Im Geschäftsbereich Des Bundesministeriums Für Ernährung Und Landwirtschaft (BMEL): 94. doi:10.5073/20240109-073031-0.
  4. ↑ Hirai, Kenji; Uchida, Atsushi; Ohno, Ryuta (2002), Böger, Peter; Wakabayashi, Ko; Hirai, Kenji (eds.), "Major Synthetic Routes for Modern Herbicide Classes and Agrochemical Characteristics", Herbicide Classes in Development, Berlin, Heidelberg: Springer Berlin Heidelberg, pp. 179–289, doi:10.1007/978-3-642-59416-8_10, ISBN   978-3-642-63972-2 , retrieved 2024-11-21
  5. 1 2 "Fact sheet HRAC Mode of Action Updates" (PDF). Weed Science Society of America. Retrieved 20 September 2024.
  6. ↑ "Overview". Herbicide Resistance Action Committee. Retrieved 20 September 2024.
  7. ↑ Busi, Roberto; Goggin, Danica E; Onofri, Andrea; Boutsalis, Peter; Preston, Christopher; Powles, Stephen B; Beckie, Hugh J (December 2020). "Loss of trifluralin metabolic resistance in Lolium rigidum plants exposed to prosulfocarb recurrent selection". Pest Management Science. 76 (12): 3926–3934. doi:10.1002/ps.5993. PMID   32638493.
  8. ↑ Oršolić, Davor; Pehar, Vesna; Šmuc, Tomislav; Stepanić, Višnja (2021-06-01). "Comprehensive machine learning based study of the chemical space of herbicides". Scientific Reports. 11 (1): 11479. doi:10.1038/s41598-021-90690-w. ISSN   2045-2322. PMC   8169684 . PMID   34075109.
  9. 1 2 "2024 HRAC GLOBAL HERBICIDE MOA CLASSIFICATION MASTER LIST". Herbicide Resistance Action Committee.
  10. 1 2 3 "Australia Herbicide Classification Lookup". Herbicide Resistance Action Committee. Retrieved 20 September 2024.
  11. ↑ "Pesticide Properties Database". sitem.herts.ac.uk.
  12. 1 2 "2008 Herbicide Mode of Action Table". weedscience.org.
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