Residues of imidacloprid in cucumber fruits and leaves were investigated under field conditions. Trails of 45 m were sprayed with imidacloprid (35 SC) at 52.5. 84.0 and 168.0 g/ha. To find out the effects of repeated spraying on residues accumulation, a second spraying (84.0 g/ha) was performed, 14 days after the initiation of experiment. Leaves and fruits were sampled at different time intervals and after extraction and clean-up the residues were, quantified by HPLC. Residues were detected up to 4 weeks after treatment. Initial deposit of imidacloprid in cucumber was 2.82 mg/kg. On the 1st, 3rd, 10th, and 14th days after application, the residue were 1.2, 0.56, 0.9 and 0.3 mg/kg respectively. In leaves 7.46 mg/kg imidacloprid was recorded, 2 hours after application. The residues dropped off sharply and was recorded 0.82 mg/kg on the
14 day after application. Small quantities of residues were recorded in cucumbers, sampled after two weeks. One day after the plants were sprayed at 168/0 g/ha, the residue in fruit was 2.27 mg/kg. The residues declined to 0.93 and 0.57 mg/kg on 3rd and 7th days, respectively, and was recorded 0.17 mg/kg on the 10th day. In leaf samples, the initial deposit was 16.8 mg/kg getting reduce to 11.20, 5.73 and 3.67 mg/kg on the 1st, 3rd and 5th day after spraying, respectively. Leaf samples analyzed on the day 10, contained 1 mg/kg imidacloprid. For spray treatment at the rate of 52.5 g/ha, initial deposit of imidacloprid in cucumber fruits declined from 0.126 to 0.067 mg/kg in one day and to 0.049 mg/kg in 3 days. The residues of imidacloprid that recovered, at day 5 and 7 were 0.05 and 0.038 mg/kg, respectively. Imidacloprid recovered after two times of spraying and at double dose, did not show any accumulation of residues in fruit.
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