Agrochemicals Herbicide Metsulfuron-Methyl

Trade name

ALLIE?; ALLY?; ALLY-20DF?; ANSWER?; BRUSH-OFF?; CANVAS?; CIMARRON?; DMC? WEED CONTROL; DPD 63760H?; DPX 6376?; DPX-T 6376?; ESCORT?; FINESSE?; GROPPER?; NUP?; PARTISAN ?; PASTURE? MD; RIVERDALE?; ROSULFURON?

Potential Exposure

Metsulfuron-methyl is a preemergence and postemergence sulfonylurea herbicide used to control annual grasses, brush, woody plants and broadleaf weeds. It can be applied to cereals including barley, rye and wheat and to pastures. It is primarily used to control brush, woody plants and broadleaf weeds on rights-of-way, fence rows, storage areas, highways and other noncrop areas.

Environmental Fate

Soil/Plant. Hydrolyzes in soil and plants to nontoxic products (Hartley and Kidd, 1987). The half-life in soil varies from 7 days to 1 month (Hartley and Kidd, 1987). Ismail and Lee (1995) studied the persistence of metsulfuron-methyl in a sandy loam (pH 5.1) and clay soil (3.1) under laboratory conditions. Degradation was more rapid in non-sterilized than in sterilized soil. In non-sterilized soil, the rate of degradation increased with increasing soil moisture content. When the moisture level in the sandy loam and clay soil was increased from 20 to 80% of field capacity at 35°C, the half-lives were reduced from 9.0 to 5.7 and 11.2 to 4.6, days, respectively. The investigators concluded that the disappearance of metsulfuron-methyl in soil resulted from microbial degradation and chemical hydrolysis.

Metabolic pathway

In soils, under aerobic conditions, metsulfuron methyl is degraded by the cleavage of the sulfonylurea linkage, resulting in the formation of methyl 2- (aminosulfonyl)benzoate, 4-methoxy-6-methyl-2-amino- 1,3,5-triazine, and saccharin as major products. Under anaerobic conditons, free acid of metsulfuron methyl and the resulting O-demethylation product are identified. The formation of two ring-opening products at the triazine moiety is observed. Under acidic conditions, hydrolytic degradation products identified are involved in the soil degradation products. In plants, the specific metabolites are identified as the hydroxylation product of the phenyl ring of metsulfuron methyl and 4-methoxy-6-hydroxymethyl-2-amino-1,3,5- triazine. Mammalian metabolites are also included in the soil metabolites.

Incompatibilities

Strong oxidizers. Stable in air to about 140 C. It is hydrolyzed in acid solutions.

Waste Disposal

It is the responsibility of chemical waste generators to determine the toxicity and physical properties and of a discarded chemical and to properly identify its classification and certification as a hazardous waste and to determine the disposal method. United States Environmental Protection Agency guidelines for the classification determination are listed in 40 CFR Parts 261.3. In addition, waste generators must consult and follow all regional, national, state and local hazardous waste laws to ensure complete and accurate classification and disposal methods. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Offer surplus and nonrecyclable solutions to a licensed disposal company. Dissolve or mix the pesticide with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber.

Definition

ChEBI: A N-sulfonylurea in which the sulfonyl group is attached to a 2-(methoxycarbonyl)phenyl group while a (4-methoxy-6-methyl-1,3,5-triazin-2-yl group replaces one of the amino hydrogens of the remaining urea group.

Agricultural Uses

Herbicide: Metsulfuron-methyl is a pre-emergence and post-emergence herbicide used to control annual grasses, brush, woody plants and broadleaf weeds. It can be applied to cereals including barley, rye and wheat and to pastures. It is primarily used to control brush, woody plants and broadleaf weeds on rights-of-way, fence rows, storage areas, highways and other non-crop areas.