Wheat in southeastern and south central Kansas is at or approaching the heading, flowering, and early stages of kernel development. These growth stages are very vulnerable to Fusarium head blight (head scab). Given the recent rainfall and associated periods of high relative humidity, there is concern that some fields are at a high risk for severe disease this year.
There is a national effort to predict the outbreaks of Fusarium head blight. These predictive models can help growers evaluate how favorable conditions are for the development of disease. In a general sense, these models are looking for weather patterns that known to favor the reproduction and infection processes of the Fusarium fungus. Many of the most severe disease outbreaks were preceded by a period of high relative humidity in the weeks leading up to flowering growth stages. The risk of severe Fusarium head blight has increased significantly this past week and much of eastern and south central Kansas is now at a moderate or high risk of disease (Figure 1). Wheat in other areas of the state is not at the critical growth stages yet; therefore, the risk of disease is lower than the current map indicates.
Figure 1. Risk of Fusarium head blight in Kansas on May 10, 2019. The latest risk maps can be found at: http://www.wheatscab.psu.edu.
Growers concerned about head blight should consider applying a fungicide after their fields have fully headed or are in the early stages of grain fill. The most effective fungicide applications for Fusarium suppression are made just as the crop begins to flower or during the early stages of kernel development. Product choice is also important for Fusarium management with the Prosaro, Caramba and Miravis Ace being the best available options. Many other fungicide products are not labeled for Fusarium management.
More information about fungicide options can be found in the publication, “Foliar Fungicide Efficacy for Wheat Disease Management” at https://www.bookstore.ksre.ksu.edu/pubs/EP130.pdf.
Erick De Wolf, Extension Plant Pathology