Over the winter meeting season, we have received questions regarding the risk of Fusarium head blight of wheat. We have already discussed identification and some of the important risk factors to consider for properly identifying Fusarium head blight in the April 10, 2008, Wisconsin Crop Manager, and more specifically, about the role of crop rotation and wheat production in the October 11, 2007, Wisconsin Crop Manager. In this article, we will illustrate how you can obtain updated risk assessment information using the Wheat Fusarium Head Blight Prediction Center. This is an online risk assessment tool that can be found at: http://www.wheatscab.psu.edu/ (Figure 1). 

 

 

Figure 1. Main page of the Wheat Fusarium Head Blight Prediction Center.

 

In order to effectively use the site, an understanding of the model basics is necessary. Taken directly from the “Model Basics” with the risk assessment tool, the Fusarium head blight models, “predict the risk of a head blight epidemic with greater than 10% field severity based on summaries of weather conditions observed during the past 7 days. The models can correctly identify years with severe head blight 7 out of 10 years. The colors on the map show the relative risk of an epidemic and are coded as; Red = High risk; Yellow = Moderate risk; Green = Low risk. The symbols on the map represent weather stations. When selected these stations provide site-specific estimates of disease risk.”

 

From the main page, there are a series of options that can be selected, including: (i) Key items to obtain a prediction, (ii) Model details, (iii) Disease information, and (iv) Risk map tool. The first three links are important and provide useful information to gain a better understanding of how the models are calculated as well as to provide a discussion of the limitations of the models. A key point for these models is that the greatest risk for Fusarium head blight is during flowering and knowledge of the flowering date is critical for the accurate use of this system. The models use weather conditions seven days prior to the flowering date to determine risk. A unique aspect of this modeling approach is the incorporation of multiple sources of weather information, including sources from the National Weather Service and weather stations maintained throughout the wheat-growing region. Another important piece of information is that the current iteration of the forecasting models do not rely extensively on the use of rainfall to maintain accuracy of the models, however, periods of unusually dry or wet weather might make the model predictions more uncertain, thus it is important to also consult the corresponding state commentary that we will provide on the Fusarium Head Blight Prediction Center website and also using “The Soy Report Blog” (http://thesoyreport.blogspot.com). Finally, it is very important to understand that the current experimental models have an accuracy of approximately 80%.

 

To help facilitate a more complete understanding of the Wheat Fusarium Head Blight Prediction Center, we will illustrate the use of the Risk map tool. From the main page, begin by selecting “Risk map tool” from the available links. This will bring up a new screen with options for using the risk map tool (Figure 2).

Figure 2. Main page for the Fusarium head blight risk assessment tool. 

In the middle is a series of steps that you help explain how to use to the risk assessment tool, including choosing the assessment date for flowering, selecting the model for wheat type (spring or winter), and using of zoom to view risk maps for the area of interest.

After selecting “OK”, we can select the model by wheat class (spring or winter). The selection will activate different components of the model for each wheat type. We then have the option of selecting the state where we are interested in the prediction (highlighted in green) (Figure 3).

Figure 3. State selection page after selecting for wheat type. 

To select a desired state, click on that state, which will pull up zoomed map that provides identification of all the available weather stations. Right now in Wisconsin, FAA weather stations are available to be selected. To further illustrate, we have selected the site for Fond du Lac. The weather station will be highlighted and the National Commentary (see Figure 3 bottom of the page) will be replaced with information about the current risk (Figure 4).

 

 

Figure 4. Illustration of the risk of Fusarium head blight on winter wheat for Fond du Lac County on April 23, 2008.

 

Within the section describing the risk, there are two further options you can explore, including “View Model Parameters” and “View Commentary”. If you select “View Model Parameters”, there are summary plots that illustrate components that are used in the model. Duration variables include T3 (Hours of temperature between 9 and 30°C (48 and 86°F)), R2 (hours in which rain occurred), and TH2 (Hours of temperature between 9 and 30°C (48 and 86°F) and relative humidity ³ 90%). Furthermore, there is measure of daily average relative humidity in a second plot. Clicking on the “View Commentary” will bring up the commentary that we will provide throughout the growing season about current disease pressure, wheat growth stages and development, and recommendations for managing wheat and will also summarize for “The Soy Report Blog”.