Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/1995
Publication Date: N/A
Interpretive Summary: All the certified seed of Chewings fescue in the USA is produced in Oregon with a farm value of $5.7 million. Stem rust was found for the first time in Chewings fescue throughout the Willamette Valley in Oregon in 1993. A study was done using this form-species of stem rust to compare virulence among isolates and susceptibility among cultivars of Chewings fescue. In addition, four other species of cool-season grasses were inoculated to determine the host range of this form-species. Stem rust was severe on 12 cultivars of Chewings fescue and all were rated as stem rust susceptible. Stem rust was less severe in red fescue cultivar Crestlawn. Despite having lesions develop in a few inoculated plants of sheep fescue and perennial ryegrass, these hosts probably are not susceptible to stem rust in the field. Stem rust did not develop when tall fescue was inoculated with the fungus. No difference in virulence was observed among stem rust isolates collected in three locations within the Willamette Valley. Out of 673 plants of Chewings fescue inoculated, 8% were resistant to stem rust. A stem rust resistant germplasm could be developed for Chewings fescue as has been done with other species of cool- season grasses and other open-pollinated grass hosts.
Technical Abstract: Stem rust was found on Chewings fescue throughout seed production areas of the Willamette Valley of Oregon in 1993. When seedlings of cultivar Jamestown were inoculated with isolates of stem rust, collected from three locations, no difference in plant response was observed among isolates. When 12 cultivars of Chewings fescue were inoculated with a mixture of these three isolates, cultivar Longfellow was less susceptible to stem rust than the other 11 cultivars, but no cultivar was rated resistant. Four other species of cool season grasses used for turf (red fescue, tall fescue, sheep fescue, and perennially ryegrass) were also inoculated with the same mixture of isolates of stem rust. Stem rust infected 24 of 60 seedling of red fescue cultivar Crestlawn and was less susceptible to stem rust than Chewings fescue. Despite infection of five of 46 seedlings of sheep fescue and one of 60 seedlings of perennial ryegrass, these hosts probably are not susceptible to stem rust in field conditions. Pustules of stem rust did not develop in tall fescue inoculated with these collections of stem rust. This is believed to be the first report of Puccinia graminis subsp. graminicola on Chewings fescue in Oregon.