Persistence and dissipation of synthetic pyrethroid residues on chickpea

Persistence and dissipation of insecticides viz., synthetic pyrethroids (deltamethrin, cypermethrin and fenvalerate) is reported on the straw and pods of chickpea. Insecticide residues were heavily deposited on the leaves and pods, just after spraying and dissipated as the first order reaction in the subsequent days. Minimum persistence was observed in the deltarnethrin, only 1 to 3 days in pods and 3 to 7 days in leaves. Residue of fenvalerate persisted up to the harvesting but it was below the Maximum Residue Limit (MRL) of 0.2 ppm prescribed by FAO/WHO. Residues of fenvilerate and cypermethrin were above the MRL after one week of spraying. Residue levels in leaves were higher than pods. Level of initial deposition after first spraying was always higher than second and third spraying.