Residue and persistence of insecticide l-(2-chlorobenzoyl)-3-(4-chlorophenyl)urea in C hinese cabbage and soils in the Northern China

The residue and persistence of the insect growth regulator 1-(2-(chlorobenzoyl)-3-(4-chlorophenyl)urga(CCU)in Chinese cabbage and soil in the field were studied in Northern China during 1988-1989．The degradation of CCU in soils was also studied under laboratory conditions．The CCU was found to be unstable in Chmese cabbage and soil in field．The half-life ofCCU was 13.2-14.0 days in Chinese cabbage and 8.8-27.0 days in soil,respectively．Three ppm as the maximum residue level for CCU in Chinese cabbage and 21 days as the preharvest interval for the vegetable treated with CCU were recommendced．