Terrestrial field dissipation of diclosulam at four sites in the United States

The soil dissipation of diclosulam was studied using C-14-labeled and nonra diolabeled material in Mississippi, North Carolina, Georgia, and Illinois b etween 1994 and 1997. The test substance was preemergence broadcast applied at target rates of 35 and 37 g ai ha(-1) for the 14C-labeled and the nonra diolabeled studies, respectively. The degradation of diclosulam was rapid w ith half-lives ranging from 13 to 43 days at the four sites. Rapid degradat ion rates and the increasing sorption to soil over time resulted in low per sistence and mobility of this compound. Metabolite formation and dissipatio n in the field reflected observations of photolysis, hydrolysis, and aerobi c soil metabolism studies in the laboratory. The rapid field dissipation ra tes, metabolite formation patterns, and sorption characteristics obtained i n these field studies were consistent with the laboratory data generated fo r diclosulam, and reflect the multiple concurrent degradation mechanisms oc curring in the field.