June 3, 2004
With frequent rains/showers in the last three weeks, wheat crops look much better in central and eastern Washington and Idaho. The favorable weather conditions also have made stripe rust develop quickly in these areas. In central Washington, especially around the Connell area in Franklin and Adams counties, crops in several fields of the ‘Hatton’ hard red winter wheat were covered with rust. These fields have not been sprayed with fungicides, which have continued producing huge amount of rust spores that have spread in the central and eastern Washington and northern Idaho. Yield losses in these fields will be more than 20%. If susceptible varieties like ‘Hatton’ had not been planted last fall, the rust pressure this year would have been much lower. ‘Finley’ fields had much less rust, 5-20% severities with mainly resistant reactions. ‘Eltan’ fields were basically rust-free in this area.
In Walla Walla, stripe rust was up to 60% of severity on susceptible winter wheat varieties and up to 10% on susceptible spring wheat varieties in experimental plots on June 2. In the experimental nurseries, severe rust was on ‘Hatton’, ‘Walladay’, ‘Cashup’, ‘Wanser’, ‘Buchanan’, ‘CDC Falcon’, and ‘Columbia 1’. A few rust pustules were found on ‘Hiller’, ‘Edwin’, ‘Lewjain’, ‘OR990553’, ‘Albion’, ‘Weston’, ‘Boundary’, ‘Symphony’, ‘Nuhorizon’, and ‘Nuhills’. As expected, commercial fields of ‘Eltan’ and ‘Madsen’ did not have rust in the Walla Walla and other counties.
In this week, Stephen Jones found stripe rust on ‘Edwin’ near Kahlotus, in Franklin County. John Burns reported stripe rust on flag leaves of the ‘Nuhorizon’ hard white winter wheat near Lamont in Whitman County. Kim Campbell observed stripe rust on winter wheat in experimental plots near Ralston in Adams County. Gary Shelton also found stripe rust showing up on spring wheat plots.
Stripe rust just started showing up on susceptible varieties of both winter and spring wheat in experimental plots near Pullman, up to 2% of severity and less than 5% of plants infected by June 1.
Based on the weather conditions in the last couple of weeks and forecasted for the next 10 days, stripe rust will develop quickly on susceptible varieties of both winter and spring wheat in the Pacific Northwest. According preliminary results of stripe rust samples from California, western Oregon, and northwestern Washington, races predominant in the last year will be predominant this year, but changes in rust virulence also have occurred. Stripe rust samples from Jim Peterson of Oregon State University showed that the ‘Foote’ winter wheat and ‘Hank’ spring wheat became highly susceptible in the Willamette Valley, Oregon. These varieties were high resistant in the past. Therefore, if you grow these varieties this year, please watch closely at these fields, as well as fields planted with cultivars (e.g. ‘Zak’, ‘Nick’, ‘Jubilee’, ‘Winsome’, ‘Scarlet’, and ‘Macon’) that were susceptible or moderately susceptible last year. If you see about 5-10% of either rust severity (percent of leaf areas infected) or incidence (percent of plants infected), you should consider use of fungicide. Tilt, Quadris, Quilt, Headline, and Stratego are available for control of stripe rust. If you have any questions, please contact me (Phone: 509-335-8086, E-mail: email@example.com) or David Wood (Phone: 509-335-4789, E-mail: firstname.lastname@example.org).