Economic threshold for chemical control of spotted bollworms (Earias vittella and E. insulana) and pink bollworm (Pectino phora gossypiella) on tree cotton (Gossypium arboreum)

Abstract

An experiment was conducted during 1991-93 to study the control of spotted bollworms [Earias vittella (Fabr.) and E. insulana(Boisd.)] and pink bollworm [Pectinophora gossypiella (Saund).] based on bollworm population or infestation level in fruitingbodies of tree or desi cotton (Gossypium arboreum L.). Fenvalerate (50 g al/ha) alternated with quinalphos (0.5 kg ai/ha) wasused in all the treatments. Six sprays of these insecticides in the recommended criterion (spray at 10-day intervals startingfrom squaring on 25% plants till Z weeks before the first picking) on cotton controlled the bollworms most efficiently, asthe highest seed-cotton yield (1 718 kg/ha) as well as net income (Rs 23 375/ha) were obtained under this treatment.Insecticidal sprays at 5% incidence in freshly shed fruiting-bodies (5 sprays) was the next in effectiveness. Sprays done atstage of 2 larvae/plant and 10% incidence in intact fruiting-bodies on plant were found the least effective.