灭多威在棉花及土壤中降解动态及残留量研究

按生产上常规用量，每亩喷施２０％灭多威乳油６０毫升防治二代棉铃虫，施药后７天在棉叶上及１４天在土壤中其降解率分别为９８．８１％及８８．０９％；半衰期分别的１．５６天及４．９８天。防治二、三、四代棉铃虫，按有效剂量施药６次，有效成分７２克／亩，棉籽和土壤中的最大残留量分别为０．０２３及０．０８４微克／克；再加大５０％用量，有效成分１０８克／亩，最大残留量仅为０．０３４及０．２１４微克／克。结果表明，灭多威在棉叶上及土壤中降解较迅速，常规用量下，对棉籽及土壤污染较轻。

Study on Residue and Degradation of Methomyl in Cottons and Soils

Spraying methomyl 20 EC at the rate of 900ml/ha in cotton fields to control the cotton bollworms of the second generaton,the degraded rates of methomyl in cotton leaf after seven days and in soil after fourteen days of application were respectively 98.81% and 88.09%,and the half-lives of degradation were 1.56 days and 4.98 days respectively.After 6 times of application with total 1080g of active ingredient of methomyl per ha.in cotton's full-season, the maximum residues in cotton seed and soil were 0.023ug/g and 0.084ug/g.Increased by 50% of dose(1620g/ha),the maximum residues were only 0.04ug/g and 0.214 ug/g respectively.The results indicated that methomyl was degraded rapidly in cotton leaf and soil,and its pollution was not all serious.