Submitted to: Abstracts of International Powdery Mildew Conference
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2012
Publication Date: 8/28/2012
Citation: Rouse, M.N. 2012. Puccinia hordei isolates with virulence to both Rph3 and Rph7 detected in the United States. Abstracts of International Powdery Mildew Conference. p. 57.
Technical Abstract: Barley leaf rust resistance genes Rph3, Rph7, and Rph9 alleles have been used in agriculture to mitigate yield losses. Virulent isolates of the barley leaf rust pathogen, Puccinia hordei, have been selected due to the use of these resistance genes. Virulence to Rph9 alleles is common worldwide. During the early 1990’s P. hordei isolates with virulence to Rph7 spread throughout the United States causing yield losses as high as 40%. In 2010, high severities of barley leaf rust were found on barley cultivar Doyce, which was previously resistant. Three single pustule isolates of P. hordei were derived from collections made from Doyce barley. The isolates were characterized for virulence to barley leaf rust resistance genes by inoculating a barley leaf rust differential set including the first 15 Rph genes. All isolates were virulent to both Rph3 and Rph7. This virulence combination has previously been detected only in the Mediterranean region. New isolates of P. hordei with virulence to both Rph3 and Rph7 threaten barley production in environments conducive for disease development in the United States.