Studies on movement and placement of systematic granular insecticides in soil in relation to control of pests of pulses

Abstract

The horizontal movement of three systemic granular insecticides phorate, carbofuran and disulfoton in four different types of soils of Kerala viz. sandy, alluvial, red and laterite, was studied by observing the mortality of aphids released on cowpea plants at different distances from point of application of the granules . The effect of age of cowpea plants on the uptake of phorate was assessed by growing plants of different ages. Vertical movement of phorate and disulfoton in red soil was assessed in terms of residue levels after broadcast and point application by colorimetric and bioassay methods. The effect of placements of the systemic granules on pest infestation of cowpea was observed in a field experiment laid out in RBD and the incidence of leaf miner , aphids, flea beetle, leaf webber and pod borer was assessed . The effect of different placements of insecticides in soil on their persistance in cowpea was assessed by observing the mortality of aphids confined on the treated plants at ten-day intervals after application of the insecticides . The effect of placement of insecticide granules on plant growth characters viz. plant height, number of branches, weight of shoot, weight of root , length of tap root, number of nodules, dry weight of nodules and yield was assessed. Residues were estimated in the green pods forty-five days after application of the systematic granules.