Residue and Degradation of Metamifop in Paddy Field

Field experiments were conducted in Jiangxi and Jiangsu Provinces,separately,of spraying metamifop(10% emulsifiable solution)in paddy fields to explore dynamics of metamifop residus in the paddy fields with the accelerated solvent extraction(ASE),gel permeation chromatography(GPC) and high performance liquid chromatography(HPLC)methods.Results show that metamifop degraded quickly in the plant and water,but not so in the soil.The half-life of metamifop in plant,water and soil was approximately 3.5 and 2.2 days,1.3 and 2.3 days,11.7 and 20.2 days at Nanjing and Nanchang,respectively.When a paddy field was sprayed once with 10% metamifop emulsifiable solution at the highest recommended dose and even 2 times of that value,no residue of the substance was detected in rice straw,rice hull,brown rice and paddy soil at the harvest,which suggests that metamifop is a kind of pesticide low in residue and easy to degrade.