May 31, 2006
As I was checking wheat fields in the Palouse region today, winter wheat ranged from early boot to heading stages. I found stripe rust on susceptible wheat entries in our winter wheat nurseries in all four locations near Pullman, WA. Stripe rust also was found in the McGregor winter wheat nurseries west of Colfax. The rust severities ranged from 1 to 10% with less than 1% plants infected. The stripe rust appearance is one month later than that of last year in the Palouse Region. Today, I did not find stripe rust in commercial fields.
The showers last week have provided good moisture for crop growth, but also have created favorable conditions for stripe rust development. The weather forecast also indicates favorable conditions for stripe rust for the next two weeks. Therefore, stripe rust will be more easily fond in the Palouse region in about a week. Resistant and moderately resistant cultivars of winter wheat should be fine without fungicide application. Fields of susceptible cultivars should be checked for rust development and fungicide spray may be necessary. Although stripe rust has not been found on spring wheat in this region, spring crop is more vulnerable to the disease because several spring wheat cultivars became susceptible last year and because of the longer growth season from now on.
Since the last rust update on May 17, wheat stripe rust has been reported in Kansas, South Dakota, and Virginia in low levels.