Diphenamid metabolism in plants

Diphenamid, a herbicide, is metabolized to N-methyl 2,2-diphenylacetamide and 2,2-diphenylacetamide by the common soil fungi Trichoderma viride and Aspergillus candidus within 48 hours. The two metabolites are more toxic than diphenamid to both tomato and barnyard-grass seedlings under sterile conditions. This finding indicates that the phytotoxic moiety is not diphenamid but one of its metabolites-probably the N-methyl derivative.