The initial metabolism of acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide] in tolerant and susceptible plants was examined to determine if metabolism is a factor in the selective phytotoxicity of this herbicide. Six crop and ten weed species were used. In every case acetochlor was converted initially to thioether conjugates. In thirteen of the species, initial conjugation was with glutathione (GSH). The homoglutathione (hGSH) conjugate was formed in three legumes. Tolerant plant seedlings metabolized acetochlor more readily than susceptible plant seedlings. Based on these results, acetochlor detoxification is a primary factor in the selective phytotoxicity of this herbicide.
