Determination of Waiting Period and Harvest Time Residue of Imidacloprid 17.8/SL in Chillies

摘要

Field experiments were carried out to determine the harvest time residues of imidacloprid 17.8/SL after application and to determine its half-life and waiting period in chilli fruits. The results revealed that harvest time residues of imidacloprid 17.8/SL on chilli fruits were at below detectable level (BDL). Dissipation of initial deposits was from 18.16 to 31.40 and 15.05 to 32.18 per cent, respectively in the field experiment I and II, after one day of treatment. The residues reached BDL after third day at 15 and 25 g a.i./ha, fifth day at 50 g a.i./ha and seventh day at 100 g a.i./ha in both the field trials. The half-life values of imidacloprid 17.8% SL applied as foliar treatment at 15, 25, 50 and 100 g a.i./ha were 3.76, 2.85, 2.32 and 2.29 days in the first experiment and 4.27, 2.66, 2.32 and 2.48 days in the second experiment, respectively. Considering the Maximum Permissible Residue Limit (MRL) of 1.0 ppm for chilli, the suggested safe waiting period after spraying of imidacloprid at 25,50 and 100 g a.i./ha was 0.75, 2.46 and 4.2 days in the field experiment I and 1.24, 2.69 and 4.56 days in the second experiment, respectively.