Source: Katelyn Willyerd, Pierce Paul, Dennis Mills, Ohio State University
Reports from Southern Ohio indicate wheat has entered the flowering growth stage, making the crop vulnerable to Fusarium head blight (head scab). For wheat flowering between May 14 -17, the risk assessment tool (www.wheatscab.psu.edu) indicates a low risk of scab for the majority of Ohio. The tool uses weather conditions seven days leading up to flowering to calculate risk. In general, prolonged periods of warm and wet conditions increase the risk of scab. Cool weather last week and dry conditions experienced over the weekend have minimized the scab risk. Since May 1, we have had fairly frequent, but variable amounts of rainfall, ranging from 0.05 to a little over 3 inches, depending on where you are in the state. During this same time, temperatures have been on the cool side, with an average high of 66 F and low of 47 F. So even though it may be raining today, the previous six to seven days have been cool, with several days without rain.
A moderate scab risk is predicted for portions of Lawrence and Gallia counties (just north of Huntington, West Virginia) for wheat flowering on May 17-18. Please check the risk assessment tool frequently over the next few days to monitor your scab risk level. If wet, humid conditions continue, the scab risk may increase and spread to other wheat-growing counties in Southern Ohio. A well timed fungicide application at flowering will reduce scab severity and vomitoxin contamination. Please contact your local extension educator and state specialist to discuss your concerns and management options.
If it warms up over the next few days, current rainfall patterns may increase the risk of scab in areas of Central and parts of Northern Ohio, where the wheat will likely begin to flower by the end of this week. For instance, in Wooeter, the forecast is for more rain today, 50 percent chance of rain over the next two days, followed by a dry day, and then more rain the following two days. Temperatures are forecasted to reach mid 70s later this week. So, if the forecast is true (worse case scenario) and your wheat flowers on Friday of this week, you would have had 6 out of 7 days with some rain by the time your crop flowers. As your wheat approaches flowering, check the risk tool frequently. You may use up to 72 hours of forecasted weather data to predict scab risk. We will continue to monitor the scab risk in Ohio and provide updated commentary and alerts.
An Ohio Factsheet for Head Scab is located on the Ohio Field Crop Disease Web site. Go to the front page "Wheat Fusarium Head Blight Prediction Center" and click on (Fact Sheet) http://www.oardc.ohio-state.edu/ohiofieldcropdisease/wheat/Wheat_Scab_Risk_Tool-1.pdf