Degradation and Mobility of Sulfometuron-methyl (Oust Herbicide) in Field Soil

The degradation and mobility of sulfometuron-methyl and potential degradates were evaluated under actual field conditions in the United States following application of Oust herbicide to bare ground at the maximum labeled rate. Sulfometuron-methyl degraded rapidly at the four test sites; calculated half-life (t 1/2) values ranged from 12 to 25 days. Sulfometuron-methyl residues were below the limit of quantitation (10 ppb) beyond 90 days after treatment (DAT) at all test sites. The highest degradate concentration present at the end of the study (359 DAT) was 40 ppb (the herbicidally inactive 2-amino-4,6-dimethylpyrimidine). Sulfometuron-methyl and its degradates were immobile under field conditions. Keywords: Sulfometuron-methyl; degradation; mobility; half-life; soil