Stripe rust report May 1: No rust found in commercial fields

By Dr. Xianming Chen

On April 26 and 27, we were planting spring cereal nurseries and taking the first notes of the winter nurseries at Mount Vernon, Wash. The winter plants were at middle jointing stage (Feekes 6 on average). Wheat stripe rust was up to 80% severity on susceptible varieties. Barley stripe rust was up to 40% severity. The severity levels were normal for this location.

On April 28, we were checking winter wheat fields in the Horse Heaven Hills area in Benton County and in Walla Walla, Columbia, and Garfield counties of Washington and Umatilla County of Oregon. Winter wheat ranged from Feekes 4 to 6. No rust was found in any checked commercial fields and our experimental fields. The absence of stripe rust in our monitoring nursery at Walla Walla was different from the normal appearance of the disease in early March at this location, but similar to the absence of rust in the middle April of the last year. As stripe rust pressure is currently low in the eastern Pacific Northwest, fungicide application is not recommended in the early growth season for winter wheat, unless stripe rust is observed in fields. 

In addition to Washington, wheat stripe rust has been reported so far in Texas and Oklahoma, and barley stripe rust in Arizona.