Dissipation Kinetics and Risk Assessment of Thiamethoxam 25 % WG Residues in Vegetable Cowpea

A field experiment was conducted to study the rate of dissipation thiamethoxam 25% WG in vegetable cowpea. Thiamethoxam 25%WG @ 0.24 ml l-1 sprayed at pod formation stage, and samples pods were harvested 0 (2 hr after spray), 1, 3, 5, 7, 10, 15 days spray. Residues estimated using liquid chromatography tandem mass spectrometer (LC-MS/ MS) All-India Network Project on Pesticides Residues, College Agriculture, Vellayani, Kerala. The mean initial residue found be 0.53 ?g g-1, residues observed persisting up three reached below quantification level fifth day.