By Dr. Xianming Chen
Based on the weather conditions in November and December 2022, stripe rust in the 2023 wheat growing season is forecasted to be in the lower range of moderate epidemic level (20-40% yield loss on susceptible varieties).
Using forecast models based on the 2022 November and December weather data, yield loss of highly susceptible winter wheat varieties in the 2023 crop season is forecasted to be in the range of 16 to 33% with an average of 21% using different models. This number is lower than the forecast (34%) made last January for the 2022 crop season due to the relatively cold weather of December 2022 compared to December 2021. Currently grown varieties are forecasted to be 0 to 15% yield losses depending upon the level of resistance or susceptibility of individual varieties. Based on the forecast, fields grown with susceptible winter wheat varieties (stripe rust ratings 7 to 9) may need the early fungicide application at the time of herbicide application and varieties with ratings 0 to 6 may not need fungicide application.
The early prediction made in January is often close to the real situation, but usually may not be as good as the prediction in March based on the entire winter weather. We will make another prediction in early March. However, stripe rust resistant or moderately resistant varieties (stripe rust ratings 1 to 4 in the Seed Buying Guide) should be planted for spring wheat crops.