采用气相色谱法及田间试验方法,研究哒螨灵在香蕉及其土壤上的残留消解动态.结果表明,哒螨灵在香蕉上的原始沉积量较低,＜0.250 mg/kg,施用加倍剂量的原始沉积量与施药后14d内的残留量均明显高于施用推荐剂量,该两个处理在施药后21 d的残留量均＜0.005 mg/kg.哒螨灵在香蕉及其土壤上的残留消解规律符合一级动力学关系,在香蕉上的相关系数r=0.900 3～0.915 6(P＜0.01),消解系数k=0.246 85±0.007 95,半衰期T1/2为2.8d～2.9d,消解99％所需要的时间T0.99为18.1 d～19.3 d;在土壤上r=0.911 5(P＜0.01),k=0.145 0,T1/2为4.8 d,T0.99为31.8 d.在香蕉采收时最终产品及其土壤上均未检出哒螨灵残留.%A field experiment was conducted to reveal residual degradation dynamics and the final residues of pyrimethanil in tomato and soil, and application safety was assessed. The degradation dynamic test results showed that the half-life of pyrimethanil in soil and tomato was 7.3-10.1 d and 2.1-2.5 d, respectively. The final residue tests showed that pyrimethanil 70% WG was sprayed for 3 to 4 successive times at application dose (a.I.) 577.5 g/hm2 and 866.25 g/hm2, at 3th day after the last application, the final residues of pyrimethanil in tomato was 0.043-0.352 mg/kg, which was below the MRLs of USA. Therefore, preharvest interval was suggested to be 3 days when pyrimethanil was applied at recommended dosage for tamato.
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