Pesticide Residue Laboratory, Indian Institute of Horticultural Research, Hessaraghatta, Bangalore-560 089.
Four promising synthetic pyrethroids viz. permethrin, cypermethrin, fenvalerate and deltamethrin were evaluated for the persistence and dissipation of their residues on french bean with respect to commonly used insecticide endosulfan. Synthetic pyrethroids persisted longer irrespective of their application rates over endosulfan. The dissipation rate of pyrethroids followed the half life range of 2.5 to 3.5 days as against 1.3–1.8 days for endosulfan. Accordingly pyrethroids required waiting periods of 0–8 days based on the their maximum permissible levels as eompared to 1.5–2.3 days for endosulfan.
