Residual Toxicity and Residues of Some Insecticides in/on Gram

Abstract

Sprays of monocrotophos 008%. endosulfan 0.07%, dimethoate 0.03%, phosphamidon 0.05% and permethrin 0.005% on gram gave more than 90% kill of the larvae of He/iothis armigera Hubn. upto 3 days. Residual toxicity was noticed upto 30 days for monocrotophos, endosulfan and permethrin and upto 21 days for dimethoate and phosphamidon. On the basis of LTso values the order or residual toxicity was: monocrotophos> permethrin > endosulfan > phosphamidon > dimethoate. The residues of endosulfan and monocrotophos were found to persist for 25 days on gram leaves and for 21 days on gram pods, but the residues reached below tolerance limit of 2 ppm for endosulfan and 1 ppm for monocrotophos in 15 days on gram leaves and in 9 days in gram pods, indicating waiting period for consumption of leaves and pods for vegetable purpose. No residue in grains at harvest was detected.