Distribution, prevalence and new physiologic races of wheat stem rust in Brazil, from 1974 to 1978

Abstract

Races 11, 11/65, 11/74, 11/78, 15/65, 15/78, 17, 17/61 and 17/63 of wheat stem rust (Puccinia greminis Pers. f.sp. tritici Ericks & Henn) were identified on 1,555 samples collected from 1974 to 1978 in the Brazilian wheat regions. Race 11/78 was determined for the first time on a sample collected in 1976, and race 15/78, in 1977. The most prevalent races during this period were 11/74 and 15/65. The genes Sr 22, Sr 24, Sr 25, Sr 26, Sr 27 confer resistance to all occurrent races.