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Disease Note.

Sources of Resistance to Stem Rust in Barley. R. Dill- Macky, Queensland Wheat Research Institute, P.O. Box 2282, Toowoomba 4350. R. G. Rees, and W. J. R. Boyd. Queensland Wheat Research Institute, P.O. Box 2282, Toowoomba 4350, and University of Western Australia, Nedlands 6151, Australia. Plant Dis. 76:212. Accepted for publication 18 September 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0212D.

Epidemics of stem rust, caused by Puccinia graminis Pers.:Pers., occurred during 1982-1984 in crops of barley (Hordeum vulgare L.) in Queensland (I). In 1985, 370 disease-free selections from a 1983 CIMMYT nursery in Mexico were screened with P. g. tritici Eriks. & E. Henn. (Pgt-LSH) in the field. Selected lines were further evaluated in the field with Pgt-LSH in 1986 and 1987, with P. g. secalis Eriks. & E. Henn. in 1986, and with a putative hybrid of these forms (Pgh) in 1986. Rust development was minimal in lines Q21861, Q21928, and Q21972, and grain yield and quality were not reduced. In subsequent nurseries (1988-1990), rust development was considerably lower in these three lines (av. 4%) than in the moderately resistant cultivat Grimmett (av. 23%) (1). The resistance of the three lines can be detected by reduced seedling receptivity (uredia per square centimeter) between 10 and 28 C. In all tests, Q21861 was the most resistant line, significantly less receptive to Pgt (LSH, MMB) and Pgh than the cultivars Chevron (T gene) and Heitpas 5 (T2 gene). Although the parentage is unknown, these lines may provide valuable sources of resistance to P. graminis, particularly in areas where the new race Pgt-QCC is important.

Reference: (I) R. Ditt-Macky et at. Aus!. J. Agric. Res. 41:1057,1990.