New barley leaf rust pathotype detected in Western Australia

A new pathotype of the barley leaf rust pathogen, Puccinia hordei, was detected in Western Australia from samples collected in mid-September August 2013. The new pathotype, 5457 P-, is a single-step mutational derivative of an existing pathotype, 5453 P-, with added virulence for Rph3. This is the third pathotype of P. hordei recorded in Australia with virulence for Rph3. The new pathotype is very similar to one detected in northern NSW in late 2008, pt. 5457 P+, but differs in being avirulent for Rph19. It is expected that the new pathotype will not alter the response of barley cultivars in eastern Australia, should it migrate to this region. Tests are currently underway to assess its full impact on cultivars (Bass, Fairview, Finniss, Fitzroy, Grange, Henley, Oxford, Wimmera and Yarra) and advanced breeding lines carrying the gene Rph3. The leaf rust response of 3 of these cultivars (Grange, Henley, Oxford) is not expected to change markedly due to the additional presence of the adult plant resistance gene Rph20.