An online tool that wheat growers can use to determine their crop's risk for Fusarium head blight development has gotten an update that now allows growers to include more personalized information to get closer look at the risk in their area, said a wheat expert from the College of Food, Agricultural, and Environmental Sciences at The Ohio State University.

With Ohio wheat nearing or at the critical flowering growth stage, it's important for growers to know their risk for Fusarium head blight development, said Pierce Paul, an Ohio State University Extension wheat researcher.

Fusarium head blight, also called head scab, is of particular concern for growers during this growth stage because wheat heads are most susceptible to the scab fungus during flowering, and infection is favored by warm, wet or humid conditions, Paul said. Paul is also a plant pathologist with the Ohio Agricultural Research and Development Center.

OSU Extension and OARDC are the outreach and research arms, respectively, of the college.

Statewide, as of the week ended May 17, most of Ohio had some precipitation, with the heaviest rainfall amount in the northwest part of the state, according to the U.S. Department of Agriculture's National Agricultural Statistics Service.

"High humidity limited field drying between showers, creating additional obstacles to planting," the agency said in a written statement.

Scab can be a devastating wheat disease in Ohio because the scab fungus can cause vomitoxin contamination, making the grain unfit for marketing and unfit for human or animal consumption, Paul said.

"Growers can experience a 50 percent or more crop loss even if they have only 10-15 percent of scab in their fields, because more than 2 parts per million vomitoxin in the grain could cause the grain to be rejected or priced down," he said.

To assess the risk for scab and to determine whether a fungicide application at flowering is warranted for scab control, growers should use the Fusarium Risk Assessment Tool available at the Fusarium Head Blight Prediction Center website, wheatscab.psu.edu, Paul said.

The scab forecasting system uses temperatures and relative humidity conditions up to flowering to calculate scab risk, helping growers determine whether there is a high, moderate or low risk for the disease, he said.

To use the system, growers need to select the state (Ohio in this case), wheat type (winter) and their flowering date, which is the day when anthers are first seen sticking out of the heads. New this year, growers can assess the risk of scab development based on the susceptibility of the variety planted in their fields, Paul said.

"Color patterns across Ohio and neighboring states will then indicate the level of risk in the region for the flowering date selected," he said.

Red indicates a high risk, followed by yellow for moderate risk and green for low risk, Paul said.

"In addition to the data growers can get from using the scab forecasting system, the tool also offers a commentary section that provides up-to-date information on scab development," he said. "This can help growers decide if they need to apply fungicide based on their field's risk."

To control this disease, growers need to apply either Prosaro or Caramba fungicides at flowering, Paul said.

"Fungicides are most effective against scab and vomitoxin when applied at flowering," he said.

"An earlier application before flowering is typically less effective at suppressing scab and vomitoxin than applications made at flowering or a few days after."