Greenbug Resistance in Sorghums¹

Abstract

Resistance to the C biotype of the greenbug, Schizaphis graminum (Rondani), a pest of recent economic importance on sorghum in the United States, was discovered in Sorghum virgatum (Hack.) Stapf. Otherwise, general susceptibility to the greenbug appeared in a wide array of sorghum germ plasm, including representatives from each of the major groups in the genus Sorghum . On the basis of seedling survival, entries were classified as resistant, intermediate, and susceptible. Classifications were confirmed by plant and greenbug reactions following confinement of greenbugs to seedlings. Tolerance appeared to be the major component of resistance, but resistant and susceptible seedlings could be readily separated on the basis of greenbug populations and injury to plants in greenhouse preference trials. Resistance appeared to be conferred by dominant genes at more than one locus. Preliminary observations indicate the type of resistance discovered may be valuable under field conditions.