RESIDUE DYNAMICS OF MANCOZEB AND ITS METABOLITE ETHYLENETHIOUREA IN POTATO AND SOIL

A field experiment was conducted to reveal dynamics of Mancozeb and its metabolite ethylenethiourea(ETU) residues in potato and soil. The results showed that the average recoveries were 85.41%—95.47% for Mancozeb and 87.71%—92.19% for ETU in potato, and 85.61%—103.09% for Mancozeb and 91.08%—94.46% for ETU in soil, respectively. Mancozeb and ETU dissipated rapidly in potato. The half-life of the former(Hefei city)in potato was 6.41d—7.89d and of the latter(Tianjin city)6.16d—7.15d. And they also degraded rapidly in the soil, with their half-life being 5.26d—7.71d and 9.80d—10.16d, respectively. The results of the two-year experiments showed when the potato was sprayed four times with 3240gai·ha-1 Mancozeb/cymoxanil 72% WP,and the last application was done 7 days before harvesting,the residue of Mancozeb in potato was lower than 1.0 mg·kg-1 and ETU residue below 0.05 mg·kg-1,demonstrating that it is safe to apply Maneozeb to potato with the recommended rate.