The fate of 14C-sethoxydim {2-[1-(ethoxyimino) butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} in an aqueous solution and on glass exposed to light was evaluated. Within 1 h, more than 80% of the 14C-sethoxydim was transformed to six major products. Qualitatively the transformations were similar for both systems, and a single end product constituted the majority of 14C after 72 h. Two transitory compounds were found to be phytotoxic to barnyardgrass [Echinochloa crus-galli (L.) Beauv. ♯ ECHCG] and were more stable than sethoxydim. A nonphytotoxic compound isolated and identified by mass spectroscopy was desethoxy-sethoxydim.
