Abstract

The application of phorate through soil resulted in the resurgence of aphids and jassids when the toxicity of the chemical vanished. Aphid resurgence was noticed from seventh week and the maximum reached during the eighth week after sowing and the jassid resurgence was delayed by a week. The aphid size was increased on treated plants when the toxicity was over and the size could be related to population build-up. The pest flare-up was due to alteration in the physiology of plants by the enhanced supply of phosphorus from the insecticide. This was associated with increase in ammoniacal nitrogen, potassium and decrease in carbohydrates and calcium contents which seemed to be favourable for aphids and jassids.

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