Survey of physiologic races of Puccinia graminis avenae in Rio Grande do Sul

Abstract

Races 3 A, 3 B, 3 C, 4 A, 4 B, 4 D, 6 A, 6 B, 7 A, 7 B, 7 C, 12 A and 12 B of the oat stem rust (Puccinia graminis Pers. f. sp. avenae Eriks. & Henn) were determined on 711 isolates from samples collected in Rio Grande do Sul, from the year 1959 to 1970. Rares 3 C, 4 B, 4 D, 6 A, 6 B, 12 A, and 12 B were isolated for the first time in Rio Grande do Sul. Presently 3 A and 3 C are the most frequent races, they were identified in more than 60% of the isolates. Resistance to all ocurrent races is conferred by combining genes A, BC and E or genes A, BC and an indetermined gene carried by the cultivar Saia.