Degradation of the herbicide diclofopmethyl in soil and influence of pesticide mixtures on its persistence.

The degradation of the herbicide [14C]-diclofopmethyl was investigated in moist
parabrown podzol soil at 22°C. Radiochemical procedures were used to monitor the herbicide
breakdown. The mineralization of the uniformly labelled aromatic ring was pursued by
trapping the 14CO2 generated for 96 days. Diclofop-methyl was rapidly degraded in the soil
with a half-life of about 8 days. The major breakdown product was the corresponding aciddiclofop,
formed by a very rapid hydrolysis of the esterbond. With time the acid appeared to
undergo strong binding or complexing to the soil. An intermediate 4-(2,4-dichlorophenoxy)
phenol was recovered from the treated soil. Concentration of the phenoxyphenol increased
upto 6 days followed by quick decline. Insecticide combination of parathion + Demeton-Smethylsulphoxide
partially inhibited diclofop degradation in the soil.