By Dr. Xianming Chen
Earlier this week, we were checking wheat fields in Whitman, Garfield, Columbia, Walla Walla, Benton, Franklin and Adams counties of Washington and Umatilla County of Oregon. Winter wheat crops ranged from Feekes 4 to 6. Stripe rust was found in breeding nurseries in Central Ferry (Garfield County), our rust monitoring nurseries in Walla Walla, and nurseries at the Hermiston Station in Oregon. In our Walla Walla experimental fields, stripe rust developed in hot spots in the susceptible borders and appeared on many entries in the nurseries. No rust was found in commercial fields in Whitman, Garfield, Columbia, Walla Walla and Adams counties. However, stripe rust was observed in Horse Heaven (Benton County) and the Connell area (Franklin County). In a field east of Connell, stripe rust was easily observed on grasses, but only one infected wheat leaf was found. Stripe rust was generally hard to find, except in one field in Horse Heaven, the incidence reached 5 percent.
The previous forecast of close to normal epidemic level (18 percent on susceptible checks and 8 to 12 percent on moderately susceptible and susceptible commercial varieties) still held. The previous recommendations should be implemented: 1) For susceptible or moderately susceptible winter wheat varieties (ratings 5 to 9 on the Buyers’ Guide), use fungicides at the time of herbicide application. For varieties with lower ratings, apply fungicides only when rust is found and before it reaches 5 percent incidence or severity. 2) For spring wheat, consider planting resistant varieties (ratings 1 to 4 on the Buyers’ Guide).