Scout Now for Wheat Diseases, Prepare for Head Scab

May 5, 2010

WOOSTER, Ohio – As Ohio wheat continues to develop, now is the time for growers to scout fields for potential foliar diseases and make any necessary fungicide applications.

 

Pierce Paul, an Ohio State University Extension wheat specialist, said that much of Ohio's wheat crop is now at flag leaf emergence, also known as Feekes Growth Stage 8.

"That's the time when we recommend growers walk fields. We always want to protect the flag leaf because that's the stage that gives us the most sugars that go into grain fill," said Paul, who also holds an appointment with the Ohio Agricultural Research and Development Center. "From a foliar disease standpoint, there is not much out there right now, but if a grower has a high-yielding, susceptible variety, protecting the crop may become important as the weather changes."

Paul said that a relatively cool spring has kept diseases at bay, although some powdery mildew and Septoria leaf spot is being found in the lower canopy.

"The presence of these diseases is minor, however," he said.

The one disease that is on the minds of wheat growers is head scab, a disease that affects the wheat crop at the time of flowering. Paul said that the crop should begin flowering in late May or early June, depending on the weather and location.

"Some growers are concerned about a possible head scab epidemic because of the problems last year with Gibberella ear rot in corn," said Paul. Head scab is caused by the same pathogen that causes ear mold in corn.

"We really don't have a way of quantifying the amount of fungal spores carried over from the corn crop into the wheat fields," said Paul. "Based on the problems growers had last year with Gibberella ear mold, there could be quite a bit of inoculum floating around, especially if the wheat field is next to a no-till corn field. But whether or not we see any kind of head scab outbreak will ultimately be determined by how favorable weather conditions are for disease development."

Growers can evaluate the risk of head scab in their fields a few days ahead of flowering by using the Fusarium head blight risk assessment tool at http://www.wheatscab.psu.edu/riskTool_2010.html.

The tool, maintained by Ohio State University, Penn State, Kansas State and the U.S. Wheat and Barley Scab Initiative, uses weather conditions at the time of flowering to determine risk of head scab development. The tool is designed as a guide to help growers make the appropriate decisions on fungicide applications in the event of a potential head scab outbreak.

"Despite the ear mold problems last year, spores are always present," said Paul. "What dictates whether or not we'll have a problem is what the weather conditions are like at the time of flowering, and this tool will give growers a risk assessment based on these conditions."

Paul encourages growers to visit the web site now and become familiar with how to use the risk assessment tool before the wheat crop approaches the flowering stage.

 

Author(s): 
Candace Pollock
Source(s): 
Pierce Paul