| In order to provide basis for residual rule of 18.7 % XM·BZ(XM:dimethomorph) (BZ:pyraclostrobin) WG, The paper studies analysis methods,degradation and final residues of pyraclostrobin and dimethomorph in soil and pepper. The research include some parts:1. Residue analysis method and purification method of pyraclostrobin and dimethomorph were established in pepper and soil.2.The pyraclostrobin and dimethomorph could be extracted with acetonitrile, and then 5 gNaCl was added. After being concentrated by evaporation,use methanol to be mobile phase, the extracts were detected with HPLC-DAD. The accuracy, reappearance and precision of the method well satisfied the essential rules of pesticide residue determination.3. Degradation dynamic of 18.7 % Pyraclostrobin·Dimethomorph WG in pepper was studied by a two-year field experiments in tianjin,Shangdong and Zhejiang province. The pepper was treated with pesticide at LD and HD. Samples of soil and pepper were analysised respectively, then the degradation procedure was corresponding to the mathematic pattern: C=C0e-kt. We reached the conclusion that 18.7 % Pyraclostrobin·Dimethomorph WG was degraded easily in soil and pepper.4. Consult to trial scheme, with sprayed 18.7 % Pyraclostrobin·Dimethomorph WG on pepper three or four times at 3.74 g preparation every 20 m2 and 5.61 g preparation every 20 m2, at the interval of 10 d, after the last sprayed 1day, the results were as follows: the final residue of Dimethomorph was 0.54 mg·kg-1～2.0 mg·kg-1in pepper, the final residue of Pyraclostrobin was 0.33 mg·kg-1～0.99 mg·kg-1 in pepper. The MRLs of Pyraclostrobin in pepper were 1.4 mg·kg-1 in accordance whit the pesticide residue standards of japanese positive list system , The MRLs of Dimethomorph was 2.0 mg·kg-1 .The results showed that it was safe to use 18.7 % Pyraclostrobin·Dimethomorph WG at this recommended dosage, at three times,1d interval by safety assessment.
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