New Greenbug Resistant Sources in Winter Barley,Hordeum vulgare

Abstract

Greenbug, Schizaphis graminum (Rondani), is a chronic problem for small grains on the Southern Plains. Central to the pest status of greenbug is the occurrence of resistance-breaking biotypes. Rsg1 and Rsg2 are the only two genes for resistance of barley, Hordeum vulgare L., to greenbug. Only Rsg1 has been deployed in cultivars. Discovery of new resistant genes is essential as biotypes continue to shift. Five winter barley accessions, PI 499276, PI 565657, PI 566459, CI 2458, and PI 565676, ‘Post 90’ (Rsg1), STARS 1501B (Rsg2), and susceptible ‘Schuyler’, were evaluated in isolated cages against 14 greenbug biotypes: B, C, E, F, H, I, TX1, WY4 A, WY4 B, WY10 MC, WY10 B, WY12 MC, WY81, and WY86. Damage scores were based on a scale of 1–9 for chlorosis (1 was resistant and 9 was dead). Damage means were classified as R or S and used to construct a response matrix which indicated unique resistance genes in four lines. These new sources have potential to reduce vulnerability of barley to future outbreaks of greenbug.