CHLOROTOLURON METABOLISM IN LEAVES OF RESISTANT AND SUSCEPTIBLE BIOTYPES OF THE GRASS WEED ALOPECURUS-MYOSUROIDES

The metabolism of the herbicide chlorotoluron by susceptible and resis tant biotypes of the grass weed, Alopecurus myosuroides, was examined. After administration of radiolabelled herbicide to leaves, metabolite s were extracted and analysed. The metabolites identified consisted of mono-demethylated-, di-demethylated- and ring methyl-hydroxylated chl orotoluron. Metabolism was more extensive in the resistant biotype, yi elding principally the non-phytotoxic ring methyl-hydroxylated metabol ite. The metabolites observed are characteristic of the activity of cy tochrome P450 mixed-function oxygenase action. The specific cytochrome P450 inhibitor, 1-aminobenzotriazole, reduced accumulation of the rin g methyl-hydroxylated metabolite in the resistant biotype.