Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2006
Publication Date: April 2, 2006
Citation: Carson, M.L. 2006. Frequencies in Oat Crown Rust in the United States from 2001 through 2005. Phytopathology. 96:520. Technical Abstract: A total of 659 single pustule isolates of oat crown rust, Puccinia coronata, were collected from cultivated and wild oat (Avena sativa and A. fatua, respectively) in the major oat production areas of the United States from 2001 through 2005. They were tested for virulence on seedlings of differential oat lines in the greenhouse. A total of 175 races were found among the 340 isolates from the winter oat region of the US, whereas 216 distinct races were found among 319 isolates from the spring oat region. The crown rust population derived from winter oat in the southern US was distinct from the spring oat population in the upper Midwest, although there was no virulence unique to either population. Virulence to Pc48 and Pc52 increased significantly in both regions during the 2001-2005 time period. Virulence to Pc59 increased and virulence to Pc53 decreased in the winter oat region during the same period. Most of the virulence associations reported by Leonard et al.(2005) in the US oat crown rust population in the early 1990’s were also found in this survey. Much of the virulence diversity in the oat crown rust population in the United States can be related to the deployment of resistance genes in commercial oat cultivars and virulence associations existing in the oat crown rust population.