Greenbug Injury to Resistant and Susceptible Sorghums in the Field 1

Greenbug [ Schizaphis graminum (Rondani)] infestations causing severe damage to a susceptible grain sorghum [ Sorghum bicolor (L.) Moench], ‘Combine Kafir‐60’ (CK‐60), did not reduce grain yield of the resistant genotype ‘KS30.’ Losses in grain yield of susceptible CK‐60 were caused by both reduced seed size and numbers of seeds per head. Grain yields of susceptible sorghum decreased as leaves were destroyed by greenbugs. As greenbug damage increased, grain protein and fiber percentages increased, while fat decreased. Greenbugs seemed to reduce yields of CK‐60 more than they reduced grain quality. The data indicate that insecticides would probably not be required to prevent greenbug damage to sorghum plants possessing the resistance found in KS30 even though tolerance is a major component of its resistance.