Metamitron
Herbicide
From Wikipedia, the free encyclopedia
Metamitron is an organic compound used as a pesticide.
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| Names | |
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| Preferred IUPAC name
4-amino-3-methyl-6-phenyl-1,2,4-triazin-5-one | |
| Other names
Metamiton Methiamitron 4-Amino-3-methyl-6-phenyl-1,2,4-triazin-5-one 4-Amino-3-methyl-6-phenyl-1,2,4-triazin-5(4H)-one Goltix Herbrak | |
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3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.050.301 |
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CompTox Dashboard (EPA) |
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| Properties | |
| C10H10N4O | |
| Molar mass | 202.217 g·mol−1 |
| Appearance | Colorless-to-yellow crystals[1] |
| Density | 600 kg/m3 |
| Melting point | 167[1] °C (333 °F; 440 K) |
| 0.17% (20 °C)[1] | |
| Vapor pressure | 0.00000086 Pa (20 °C)[1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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It has been widely used in the European Union as a selective herbicide in sugar beets for weed suppression since the mid-1970's.[2][3][4]
In 2025, the U.S. EPA registered metamitron as a chemical, plant-growth regulator for thinning fruits for use on apple and pear trees.[5]
Chemical Structure and Mode of Action
Metamitron is a triazinone herbicide. It possesses a triazine ring like other organic compounds that use cyanuric chloride as a precursor. It is a modification of the chemical 1,2,4-triazin-5(4H)-one, with methyl, amino, and phenyl group substitutions at positions 3, 4, and 6.[1]
Metamitron is in the HRAC Mode of action Group 5.[6] It functions as an inhibitor of PSII by binding to serine 264 on the D1 protein.[7] Resistance to metamitron has been found in Chenopodium album growing as weeds among sugar beet fields in Belgium, caused by a mutation in serine 264.[3][7]
Metamitron is marketed by ADAMA under the trade name Goltix in Europe, the United Kingdom,[8] New Zealand, and South Africa; and as Brevis™ in the United States.[5]
Health and Environmental Impacts
Metamitron is very toxic to aquatic invertebrates, algae and to higher aquatic plants; and has a low expected acute and long-term toxicity-exposure risk for mammals and herbivorous birds.[9] In humans, metamitron has moderate acute oral and inhalation toxicity[1] and is an endocrine disruptor and may be a thyroid toxicant.[2] The major soil degradation product is desamino-metamitron.[9]