Chemical control of bollworms synchronised with flowering in cotton.

Field trials were conducted during two crop seasons to evaluate an effective insecticide for the control of cotton bollworm complex, viz., spotted bollworms (Earias spp.) and pink bollworm (Pectinophora gossypiella) Saund. Synchronising bollworms control with the phenological characters of plants, the insecticidal treatment was initiated with the setting of flowers in about 50 per cent plants. There were significant differences among the treatments to control bollworms in cotton. Four sprayings at 15-day intervals with synthetic pyrethroids, viz., deltamethrin (15–20 g a.i./ha) or fenvalerate (75–100 g a.i/ha) proved to be highly effective in reducing bollworms incidence and thereby increasing the yield of seed cotton. The superiority of synthetic pyrethroids over conventional insecticides like carbaryl and other insecticides of organophosphate group was evident.