Metabolism of bifenox in soil and plants

The herbicide, methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate (bifenox), had a half-life of 3 to 7 days after preemergence application to a greenhouse soil mix. Metabolites identified included: 5-(2,4-dichlorophenoxy)-2-nitrobenzoic acid, 2,4-dichlorophenyl 4-nitrophenyl ether (nitrofen), and 5-(2,4-dichlorophenoxy)anthranilic acid over a 313-day sampling period. Comparison of the total ¹⁴C in the soil to that extractable by methanol showed an increase in the proportion of bound material. The major metabolite eluted from a Frederick clay loam soil column was identified as the acid of bifenox and its mobility was associated with the short half-life of bifenox in soil. In vitro studies with shoot-tissue macerates showed that bifenox was not degraded by corn (Zea mays L.) or soybeans (Glycine max (L.) Merr.) and was degraded to less than 1% by velvetleaf (Abutilon theophrasti Medic.).