Potential of Heliothis spp. (Lepidoptera: Noctuidae)-Resistant Cottons in Limited-Irrigation Situations1

Abstract

Cotton cultivars with Heliothis spp.-resistant characters (glabrous, nectariless, and high gossypol) were grown under Rolling Plains conditions of limited irrigation and low nitrogen inputs. To assess resistance, data were taken on oviposition rate, numbers of larvae, and damage to squares and soft bolls. In the initial screening studies conducted from 1976 to 1978, larval numbers and damage to squares were lower in the resistant cultivars ‘HG-BR-8-N,’ ‘HG-6-1-N,’ ‘La 17801,’ and ‘HG-P-9-13’ than in the nonresistant cultivar ‘Lankart Sel. 611.’ However, yields were generally the same in all cultivars. These results prompted irrigation management studies in 1979 and 1980. When multiple irrigations were not managed to avoid Heliothis zea (Boddie) oviposition peaks, resistant cultivars did suppress damage in relation to nonresistant cultivars. However, when cotton was grown dryland, or when irrigations were managed to avoid oviposition peaks, damage to squares and soft bolls sustained by resistant and nonresistant cultivars was the same. The resistant cultivars rarely produced higher yields than the nonresistant cultivars in any of the irrigation management schemes.