Abstract

The field experiment was conducted during the Kharif, 2014 at University Farm, Post Graduate Institute, MPKV, Rahuri, District Ahmednagar to determine the residues and dissipation of deltamethrin 10 EC in/on onion and in soil. Three sprays of deltamethrin 10 EC were given at an interval of 10 days initiating first spray at bulb formation stage @ 15 g a.i./ha. (150 ml/ha) and 30 g a.i./ha (300 ml/ha). Samples were collected periodically at 0, 3, 5, 7, 10 and 15th day after last spray. The mature onion and soil samples were collected at harvest. The samples were analysed for insecticide residues by using validated QuEChERS method on Gas Chromatography Mass spectrometry. The results revealed that average initial residues of deltamethrin in immature onion were found to be 1.30 and 2.33 mg/kg at single and double dose, respectively and reached BDL on 10th and 15th days, respectively for both the doses, whereas no residues were detected in the untreated control samples. The half-life values of deltamethrin were observed to be 1.57 and 1.77 days, for single and double doses, respectively. The residues of deltamethrin in mature onion and in soil at harvest were found to be BQL. Soil sample collected after harvest did not reveal the presence of deltamethrin residues.

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