Effect of Short-Season Cotton on Overwintering Pink Bollworm Larvae and Spring Moth Emergence12

Abstract

A cultural system for short-season cotton, Gossypium spp., incorporating narrow rows (two rows ca. 36 cm apart on beds spaced ca. 102 cm apart) and early irrigation cutoff resulted in early-maturing cotton in Imperial Valley, Calif., with harvests completed by 24 August 1978. Yields were over 4,000 kg of seed cotton per ha with no insecticide applied for insect control. Cotton yields in systems with full-season, conventional-row (one row on a bed, 102 cm between rows) cultivation without insecticide treatments but with five additional irrigations were significantly lower than those in the short-season system in August and after full-season production on 15 November 1978. The early maturation of the crop in the short-season system avoided infestations of late-season, Pectinophora gossypiella (Saunders), reduced larval population in the bolls, trash, and soil (75%) in the fall, and reduced spring emergence of moths from overwintered larvae (81%) relative to the same parameters from the conventional full-season cotton crop. Cotton yields in full-season narrow-row and conventional-row systems were significantly higher when the top crop was protected from pink bollworm losses with insecticides. Cotton yields of several short-season and full-season cotton varieties and cultivars, grown under the narrow-row, short-season system, were not significantly different. Thus, currently available commercial cultivars and short-season variety genotypes are adaptable to short-season cotton growing conditions in the Southwest.