EFFECTS OF EARLY-SEASON LOSS OF FLOWER BUDS ON YIELD, QUALITY, AND MATURITY OF COTTON IN SOUTH-CAROLINA

The effect of early-season flower bud damage on yield, quality, and ma turity of cotton, Gossypium hirsutum L., was determined at Florence an d Blackville, SC, from 1989 to 1994. From 1989 to 1991, yields from in secticide-treated plots for Heliothis virescens (F.) during June were compared with plots left untreated during Tune. In all cases from 1989 to 1991, no significant differences in yield were observed between tr eated and untreated plots. From 1992 to 1994, H. virescens damage was simulated by hand-removal of newer buds. In 1992, no significant diffe rences were observed in yield, maturity, or lint quality following rem ovals as high as 100% for 4 consecutive weeks. In 1993, a 1-wk delay i n maturity was observed in 'DES 119' and 'Deltapine 90' at both locati ons following removals of 100% for 3 and 4 wk, and in 1994 at Blackvil le following removals of 100% for 3 wk. From 1992 to 1994, there were no significant yield effects following any newer 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 1 00% removal for 3 or a wk that extended into mid-July. No other signif icant interactions with removal occurred, and no differences in lint q uality were observed. Our data indicate that cotton compensates adequa tely for newer bud loss in June in South Carolina, and that insecticid es for H. virescens seldom are needed early in the season. Opportuniti es to ameliorate traditional insecticide approaches for cotton insect management are discussed by considering our data in conjunction with t he expansion of the Boll Weevil Eradication Program and the deployment of cotton cultivars that contain genes for expression of the delta-en dotoxin of Bacillus thuringiensis in other areas of the Cotton Belt.