Effects of Greenbugs on Resistant and Susceptible Sorghum Seedlings in the Field12

Abstract

Infestations of seedlings by Schizaphis graminum (Rondani) reduced grain and forage yields of a susceptible grain sorghum, Sorghum bicolor (L.) Moench, ‘Combine Kafir-60’ (CK-60), but did not reduce yields of greenbug-resistant sorghums. Greenbug feeding caused reduced tillering, plant height, and delayed maturity more in susceptible than resistant sorghums, but seed weights were not effected. Reduction in numbers of secondary culms of susceptible CK-60 appeared to be primarily, responsible for Yield losses of surviving plants. Susceptible seedlings need protection from greenbugs to achieve maximum yields. Heterozygous resistant genotypes may approach maximum yield potential without supplemental greenbug control.