First stripe rust report for 2019 calls for normal levels

From Dr. Xianming Chen

Field survey in November 2018 

On Nov. 16, 2018, our crew was checking winter wheat fields in Whitman, Lincoln, Adams, Grant and Douglas counties in Eastern Washington and found two leaves with stripe rust in only one field in Grant County near the border with Lincoln County. Wheat plants in that field were at Feekes 4. The observations indicated a relatively normal level of stripe rust infection before the winter in Eastern Washington. 

The 2019 first forecast of stripe rust for the eastern Pacific Northwest 

Based on the weather conditions in November and December 2018, stripe rust in the 2019 wheat growing season will likely be in the upper normal epidemic level range (20-40 percent yield loss). According to the forecast models, highly susceptible winter wheat varieties would have yield loss ranging from 27 to 48 percent with an average of 38 percent. Currently grown varieties would have yield losses from 0 to 19 percent depending upon the level of resistance or susceptibility. If this forecast is close to the real disease level, fields grown with moderate susceptible or susceptible winter wheat varieties (stripe rust ratings 5 to 9) would need the early fungicide application at the time of herbicide application. Based on the past experience, the early prediction made in January is often close to the real situation, but not better than the prediction in March based on the entire winter weather conditions. Therefore, we will make another prediction in early March.