Assessment of imidacloprid in brassica environment

Imidacloprid was applied as seed treatment (Gaucho 70 WS, 5 and 10 g ai kg( -1) seed) and foliar spray (Confidor 200 SL, 20 and 40 gy ai ha(-1)) at 50% pod formation stage on mustard (Brassica campestris Linn.) to control must ard aphid, Lipaphis erysimi Kalt. It was detectable upto 82 and 96 days in plants after sowing from lower and higher doses of seed treatment. However, it dissipated faster and became nondetectable after 7 and 15 days of folia r treatments from lower and higher rates of application, respectively. The dissipation models yielded the rate constants of 0.0209 and 0.0230 and 0.07 36 and 0.0779 day(-1) from seed and foliar treatment. The corresponding hal f-lives of 14.40 and 13.07 and 4.09 and 3.86 days were recorded. This sugge sted that the dissipation was independent of initial doses and followed a f irst order rate kinetics. The projected TMRC of imidacloprid from seed (0.1 36 and 0.225 mg person(-1) day(-1)) and foliar (0.069 and 0.1497 mg person( -1) day(-1)) treatments were found lower than the MPI (3.135 mg person(-1) day(-1)). At harvest mustard grains did not contain imidacloprid residues. The absence of imidacloprid in 0-10 and 10-20 cm soil layers indicated no l eaching of insecticide. Therefore, imidacloprid treatments could be taken a s safe for crop protection, consumption of leaves and environmental contami nation point of view.