Residues and Decline Dynamics of Pendimethalin in Tobacco and Soil
XIANG Zhen-bo1,SUN Hui-qing1,WANG Xiu-guo1,ZHANG Qian1,YANG Li-qiang1,YAN Xiao-yang1, SONG Chao1,XU Jin-li1,ZHENG Xiao1,fang hua2,LI Yi-qiang1 (1.Key Laboratory of Tobacco Pest Monitoring Controlling & Integrated Management,Tobacco Research Institute of CAAS,Qingdao 266101,Shandong,China;2.Institute of Pesticide and Environmental Toxicology,College of Agriculture and Biotechnology,Zhejiang University,Hangzhou 310058,China)
[Aims]In order to evaluate the safety of the use of pendimethalin in tobacco,a supervised trial experiment was conducted to study the residues and decline dynamics of pendimethalin in tobacco and soil.[Methods]Field experiments were conducted in two different locations during two years.For dissipation trial,pendimethalin was sprayed at the concentration of 2617 mg a.i./L.For final residue trial,pendimethalin was applied at 2617 and 1750 mg a.i./L,respectively,corresponding to 1.5 times recommended and recommended concentrations.Tobacco leaves and soil were sampled at 7,14,21 d after application.Pendimethalin was analyzed by high performance liquid chromatography with UV detector.[Results]Results of the decline dynamics study showed that half-life values(t1/2) were 2.56-5.97 d in tobacco leaves and 7.53-10.34 d in soil,respectively.The dissipation rates were above 90% in tobacco leaves and soil at 35 d after treatment.The ultimate residues of pendimethalin in tobacco leaves and soil were determined after the application at levels of 2?617 and 1?750 mg a.i./L,with the residues below 0.12 mg/kg in tobacco leaves and below 0.037 mg/kg in soil 21 days after treatment.