Residues of Chlorpyrifos in Cured Tobacco

The persistence of chlorpyrifos in the cured tobacco leaves was studied following foliar applications of chlorpyrifos (40 EC) @ 64 g ai ha⁻¹. The levels of chlorpyrifos residue in cured tobacco leaves increased with increase in the number of foliar applications of chlorpyrifos and pickings performed with closer interval of application. The residues of chlorpyrifos in cured tobacco leaves persisted beyond 47 days for single spray, 33 days for two sprays, 12 days after three sprays of tobacco planting. However, no residues of chlorpyrifos were detected (< 0.005 μg g⁻¹) in the fifth picking except fourth treatment (0.095 μg g⁻¹). The level of chlorpyrifos residues in cured tobacco leaves collected from different auction platforms of Karnataka was below detectable (< 0.01 μg g⁻¹).