Jassid resistance in the cotton plant

Abstract

Terminal injury by jassids, expressed as grades of plant reaction, can be related to the nymphal population, irrespective of variety and state of growth of the crop. This association enables a determination of varietal susceptibility based on injury symptoms. For each variety, susceptibility to jassid attack can be expressed as a plant resistance index. The method of sampling populations and the various grades of plant reaction recognised from normality to the extreme of jassid damage are described.