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The Fusarium Head Blight Prediction Tool Indicates High Risk

Updated August 24, 2020

Emmanuel Byamukama

Associate Professor & SDSU Extension Plant Pathologist

Map showing the risk of Fusarium head blight with green equaling no risk, yellow equaling moderate risk, and red equaling high risk. Much of the eastern half of South Dakota is red.
Figure 1. A screenshot of the scab prediction webpage showing the risk of Fusarium head blight (scab) as of June 3, 2020 for a susceptible cultivar.

Written collaboratively by Emmanuel Byamukama and Shaukat Ali.

Winter wheat is starting to flower. It is important to monitor weather conditions from when wheat is heading until flowering to decide the need for fungicide application to manage Fusarium head blight (FHB or scab). Wheat is most susceptible to Fusarium head blight around the flowering growth stage because the fungal pathogen that causes FHB infects wheat through the flower. Rainfall and warm weather during wheat heading through post flowering are the main risk factor for FHB.

The FHB prediction tools (courtesy of Penn State University and Mesonet at SDState) are indicating moderate to high FHB risk for the majority of the state for the week of June 1. Both tools use weather variables (rainfall and temperature) to predict the risk for scab. As can be seen from the map, most of the state is at moderate to high risk for FHB if a susceptible variety was planted (Figure 1).

To realize the benefits from these tools, begin by knowing the rating for scab of the cultivar planted. Scab ratings for winter wheat cultivars can be found in the most-recent Wheat Variety Trial Results. Then assess if the wheat crop is at flowering. Next consult the prediction tools to see the predicted scab risk. Finally decide on a fungicide application if the risk is moderate to high. This list of fungicides labelled for FHB courtesy of the Crop Protection Network can help aid your decision. By using the scab prediction tool correctly, a producer can protect the wheat from scab infection when the risk is moderate/high (hence avoiding dockage or rejection of grain at the elevator due to DON) or avoid unnecessary fungicides (hence saving money) in case of low scab risk prediction.