Phytotoxicity and their bio-efficacy of pesticides against key insect pests of Rabi sorghum [Sorghum bicolor (L.) Moench]

Abstract

Totally 15 pesticides were evaluated consisting of 13 insecticides, 1 acaricide and 1 botonical, along with control at 3 dosages. The pesticides were applied at 20, 60 and 90 days after sowing. Observation on different phytotoxic symptoms was recorded based on visual score (1-10) later per cent phytotoxicity was calculated. Highest mean per cent phytotoxicity index was recorded in the profenophos @ 1.0, 2.0, 4.0 ml/litre treated plots (20.2, 44.1 and 56.1 PPI) at seedling, vegetative and reproductive stage of crop growth, followed by spiromesifen. Others such as malathion, methomyl, chlorphyriphos, cypermethrin, alphamethrin, imidacloprid produced the phytotoxic symptoms to a various level. Acephate, fipronil, carbofuran, phorate, chlorantraniliprole, emamectin benzoate and NSKE were found safe to sorghum. Among chemical pesticides evaluated, carbofuran and imidacloprid were found superior in reducing the shoot fly, where as acephate, fipronil, imidacloprid and NSKE were found superior in reducing the sucking pests.