Rust Update 6/3/04

June 3, 2004

Xianming Chen

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. Yield losses in these fields will be more than 20. ‘Finley’ fields had much less rust, 5-20% severities with mainly resistant reactions. ‘Eltan’ fields were basically rust-free in this area. Although only a few thousands acres are grown with ‘Hatton’, these fields have produced huge amount of rust inoculum for central and eastern Washington and northern Idaho.

Near Walla Walla of Walla Walla County, 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 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.

Stripe rust just started showing up on susceptible varieties of both winter and spring wheat in experimental plots near Pullman in the Palouse region, 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 to preliminary results of stripe rust samples from Texas, California, western Oregon, and northwestern Washington, races predominant in the last year will be predominant this year, but changes 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 highly resistant in the past.