A New Race of Puccinia helianthi in Sunflower

Abstract

A previously unknown race of Puccinia helianthi was isolated from a commercial field of sunflower at Bushland, Texas, in 1984. Sunflower rust differential lines and cultivars that are resistant to the four North American rust races, the ten rust races of Antonelli, and the four rust races of Luciano and Luciani from Argentina were susceptible to this newly isolated race. The five sunflower germplasm lines, HA-R1, HA-R2, HA-R3, HA-R4 and HA-R5 that had been released as resistant to the four North American rust races were also susceptible to this new race. The results showed that this isolate is a new race of the sunflower rust pathogen.