From Dr. Xianming Chen
Based on the weather conditions in November and December 2019, stripe rust in the 2020 wheat growing season is forecasted to be in the severe epidemic level range (40-60 percent yield loss).
Using forecast models based on the 2019 November and December weather data, yield loss of highly susceptible winter wheat varieties in the 2020 crop season is forecasted to be in the range of 29 to 56 percent with an average of 44 percent. This number is higher than the forecast (38 percent) made last January for the 2019 crop season due to the relatively warm weather in November and December 2019. Currently grown varieties are forecasted to be 0 to 22 percent yield losses depending upon the level of resistance or susceptibility. Based on the forecast, fields grown with moderate susceptible or susceptible winter wheat varieties (stripe rust ratings 5 to 9) may need the early fungicide application at the time of herbicide application.
The early prediction made in January is often close to the real situation, but is usually not better than the prediction in March based on the entire winter. Therefore, we will make another prediction in early March. However, stripe rust resistant or moderately resistant spring wheat varieties (stripe rust ratings 1 to 4 in the Seed Buyer’s Guide) are recommended to plant.