甲霜灵在西瓜及土壤中的残留消解动态研究

Residual Dynamics of Metalaxyl in Watermelons and Soil

采用高效液相色谱检测方法．研究甲霜灵在西瓜及土壤中2a的残留消解动态及最终残留。结果表明：甲霜灵在西瓜和土壤上的半衰期为4．10。4．30d和8．61～9．55d。甲霜灵灌根施药后．西瓜全果经过14d．土壤经过28d．消解率都达到85％以上。按最高推荐剂量500g．a．i／hm2和1．5倍高剂量750g．a．i／hm2使用3—4次，收获距末次施药间隔5、7、14d，甲霜灵在西瓜全果、瓜肉和土壤中的最终残留量均低于中国食品中甲霜灵的最大残留限量标准0．2mg／kg。所以甲霜灵在海南地区西瓜上按照推荐剂量300～500g-a．i／hm2灌根2．3次。采摘间隔期7d以上是安全的。

The degradation dynamics and final residues of metalaxyl in watermelons were determined by using the high performance liquid chromatography（HPLC） through field test for two years. The results showed that the half- life of metalaxyl in watermelons and in soil was 4.10-4.30 days and 8.61-9.55 days, respectively. The digestion rate was more than 85% after 14 days in watermelons and after 28 days in soil. Although the watermelon roots were treated three or four times at the recommended maximum dose of 500 g.a.i/hm2 or even at 1.5 times of the recommended maximum dose, when harvested at 5, 7, 14 days after the last application, the residue levels in watermelons, melon pulps and the soil were less than the maximum residue limit for metalaxyl in the national food safety standard as 0.2 mg/kg. Therefore, it was safe that the watermelon roots were treated two or three times at the recommended doses of 300-500 g.a.i/hm2 and the watermelon was harvested at the 7th day after application. Metalaxyl was a safe fungicide for the soil in Hainan region.