Effects of Early-Season Loss of Flower Buds on Yield, Quality, and Maturity of Cotton in South Carolina

Abstract

The effect of early-season flower bud damage on yield, quality, and maturity of cotton, Gossypium hirsutum L., was determined at Florence and Blackville, SC, from 1989 to 1994. From 1989 to 1991, yields from insecticide-treated plots for Heliothis virescens (F.) during June were compared with plots left untreated during June. In all cases from 1989 to 1991, no significant differences in yield were observed between treated and untreated plots. From 1992 to 1994, H. virescens damage was simulated by hand-removal of flower buds. In 1992, no significant differences were observed in yield, maturity, or lint quality following removals as high as 100% for 4 consecutive weeks. In 1993, a 1-wk delay in maturity was observed in 'DES 119' and 'Deltapine 90' at both locations following removals of 100% for 3 and 4 wk, and in 1994 at Blackville following removals of 100% for 3 wk. From 1992 to 1994, there were no significant yield effects following any flower bud removal level or duration, but in 1993 at Blackville, there were significant removal X planting date and removal X planting date X cultivar interactions. In this instance, DES 119 planted late (28 May) and grown under irrigated and dryland conditions experienced yield reductions of 30-45% after 100% removal for 3 or 4 wk that extended into mid-July. No other significant interactions with removal occurred, and no differences in lint quality were observed. Our data indicate that cotton compensates adequately for flower bud loss in June in South Carolina, and that insecticides for H. virescens seldom are needed early in the season. Opportunities to ameliorate traditional insecticide approaches for cotton insect management are discussed by considering our data in conjunction with the expansion of the Boll Weevil Eradication Program and the deployment of cotton cultivars that contain genes for expression of the delta-endotoxin of Bacillus thuringiensis in other areas of the Cotton Belt.