Timing of Defoliants and Desiccants to Reduce Populations of the Pink Bollworm in Diapause1

Abstract

Diapause in the pink bollworm, Pectinophora gossypiella (Saunders), is under photoperiodic control and does not generally occur in populations near College Station, Texas, until mid-September. The termination of growth of cotton plants with chemical defoliants or desiccants before this date caused a reduction of almost 90% in the number of diapause larvae. Defoliation or desiccation of plants in early October, when most of the larvae were in diapause, was not nearly so effective in reducing the potential overwintering population as the earlier application. Results emphasized the importance of early maturity and early defoliation or desiccation of infested fields.