Effects of leaf rust on selected Australian Barleys

The effects of epidemics of leaf rust (Puccinia hordei Otth.) on grain size and yield of some commercial Australian barley cultivars were determined in 3 field experiments at or near Toowoomba in 1985, 1989 and 1990. Yield was reduced by 38% for the highly susceptible cultivar, Gus, in a mild to moderate epidemic in 1985; cvv. Prior, Schooner, Clipper, Lara and Stirling lost between 10 and 20% yield and cvv. Corvette and Grimmett were unaffected. In a mild to moderate epidemic in 1989, leaf rust reduced the yield of Gus by 40%, and of Grimmett and Clipper by 17 and 12%, respectively, while Prior and Corvette were unaffected. In a moderate to severe epidemic in 1990, yield losses were 62% in Gus, 26% in Grimmett, 31% in Skiff and 14% in the slow-rusting cultivar, Athos. No losses were detected for Corvette or the slow-rusting cultivar, Koru. Loss of yield was largely attributable to reduction in grain size.