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.