Reaction of South African rye, triticale and barley forage cultivars to stem and leaf rust

Abstract

Rusts are a significant threat to sustainable wheat production in South Africa. In addition to accurate genotyping, resistance breeding and surveillance, a better understanding of the epidemiology of rust pathogens will facilitate their control. This includes an improved understanding of over-summering and the occurrence of early-season inoculum on ancillary hosts. In the current study Puccinia graminis f. sp. tritici and P. triticina, causing stem rust and leaf rust of wheat, respectively, were avirulent on rye entries planted as forage crops in South Africa. Isolates of P. graminis f. sp. secalis and P. recondita, the stem rust and leaf rust pathogens of rye, were avirulent on all triticale forage crop cultivars screened. Puccinia graminis f. sp. tritici race PTKST, known for its broad virulence on wheat in South Africa, was avirulent on triticale cultivars when compared with race BPGSC. Similarly, P. triticina race CFPS proved to be more avirulent on the triticale cultivars than race SDDN. Results indicated that leaf and stem rust infections on rye and triticale forage cultivars do not pose a threat to commercial wheat production in South Africa. However, the field response of barley forage cultivars suggested that both ‘Mobey’ and ‘SKG9’ can serve as hosts for the wheat stem rust pathogen.