WAWG
By Xianming Chen
USDA-ARS Research Plant Pathologist
Based on the weather data of November and December 2025, stripe rust in the 2026 wheat growing season is predicted to be in the upper range of severe epidemic level (40-60% yield loss on susceptible varieties).
Using a set of forecast models based on the weather data of these two months, potential yield losses in 2026 caused by stripe rust on highly susceptible winter wheat varieties are predicted to be in the range of 35.3 to 78.2% with an average of 56.7%. The predicted severe epidemic level is attributed to the relatively warm weather so far. Based on the potential epidemic level, yield losses of commercially grown varieties are predicted to be 0 to 40% depending upon the level of resistance or susceptibility of individual varieties.
The next forecast will be made in early March based on the entire winter (November- February) weather data. According to the current forecast, fields planted with winter wheat varieties with stripe rust ratings 5 (moderate) to 9 (susceptible) may need early fungicide application at the time of herbicide application. Resistant (ratings 1 and 2) and moderately resistant (ratings 3 and 4) spring wheat varieties should be selected to plant, and varieties with moderately susceptible and susceptible ratings (6-9) should be avoided.