Residues and Degradation of Pendimethalin in Cabbage and Soil

Field trials for pendimethalin residues in cabbage and soil were conducted in Zhejiang and Fujian provinces, respectively. Residues of pendimethalin in both cabbage and soil were determined by gas chromatography with electron capture detector (ECD). The results showed that pendimethalin dissipated rapidly in cabbage and soil after application at doses of 990 and 1 485 g ai· hm- 2 with 33% pendimethalin emulsifiable concentration (EC). Its averaged half- lives of residue in cabbages in two experimental sites were 6.8 days; and the half- lives of residues in soil were different in Fujian and Zhejiang, with averaged 29.16 and 10.38 days, respectively. The final residues of pendimethalin in cabbage were less than the limit of detection (LOD) which was in line with the standards of maximum residue limit(MRL) of 0.2 mg· kg- 1 in cabbage and less than 1.0 mg· kg- 1 in soil when it was applied with an interval of 30 days after the last application. According to the results, we recommended to apply 33% pendimethalin EC one time at a dose of 990 g ai· hm- 2 with a safe interval of 30 days from harvest.