Dimethenamid

Dimethenamid is a widely used herbicide belonging to the chloroacetamide class (group 15). Group 15 herbicides inhibit synthesis of certain long-chain fatty acids, thus reducing plant growth. In 2001, about 7 e6lb of dimethenamid were used in the United States. Dimethenamid is registered for control of annual grasses, certain annual broadleaf weeds and sedges in field corn, seed corn, popcorn and soybeans. Supplemental labeling also allows use on sweet corn, grain sorghum, dry beans and peanuts. In registering dimethinamide (SAN 582H/Frontier), EPA concluded that the primary means of dissipation of dimethenamid applied to the soil surface is photolysis, whereas below the surface loss was due largely to microbial metabolism. The herbicide was found to undergo anaerobic microbial degradation under denitrifying, iron-reducing, sulfate-reducing, or methanogenic conditions. In that study, more than half of the herbicide carbon (based on 14C-labeling) added was found to be incorporated irreversibly into soil-bound residue.