Wheat scab is “disaster waiting to happen” in North Carolina

In Southeast Farm Press

Christina Cowger urges North Carolina wheat producers to be prepared for fusarium head blight or scab this year by monitoring their risks and signing up for free scab alerts from the U.S. Wheat & Barley Scab Initiative before April which is the next scab season for the state.

Speaking at the North Carolina Commodities Conference in Durham Jan. 15, Cowger, small gains pathologist at North Carolina State University, said the alerts are free and delivered by text or email. Signing up is easy at the website www.scabusa.org that allows farmers to actually look at their scab risk. The website includes daily in-season risk maps for each locale and provides scab prediction based on geography, grain type and forecast weather patterns.

Cowger cautions that scab is a disaster waiting to happen in North Carolina because studies reveal that most of the wheat varieties planted in the Tar Heel State are susceptible or moderately susceptible to fusarium head blight while  fungicides don’t offer complete control and must be applied at the right time.

“There was a terrible scab epidemic last year, particularly in Louisiana, and all the way over to Georgia. People have never seen such bad scab. It devastated the wheat industry in that area so this is a real problem. It could have just as easily been North Carolina that was devastated by scab. It’s all about the weather,” Cowger said.

In her talk, Cowger shared the results of a telephone survey of 16,000 growers of wheat and barley conducted in February 2014 by the U.S. Wheat & Barley Scab Initiative. The study was  designed to find ways to better manage scab going forward. The survey was conducted in 17 scab prone states in the central and Eastern United States and included North Carolina.

The survey showed that just 15 percent of the soft red winter wheat varieties planted in North Carolina were moderately resistant to scab. Fifty percent of the acres reported were susceptible or moderately susceptible to scab. None of the commercial varieties are fully resistant to scab at this time, Cowger said.

In addition, another  non-scientific scab survey was conducted in 2014 by the North Carolina Small Grain Growers Association and the North Carolina Cooperative Extension Service. In the study of  267 respondents from 15 counties who were questioned at Extension meetings, 200 said they planted wheat and they represented 82,000 acres planted. The survey revealed that 22 percent of those 82,000 acres were moderately resistant to scab. The rest of the acreage was either susceptible or moderately susceptible.

Cowger said both surveys make it clear that North Carolina wheat growers must monitor and manage for scab.

She encourages farmers to consider varieties that are moderately resistant to scab. “On average, good scab-resistant varieties are going to be as profitable we predict as scab susceptible varieties when you factor in the scab risk, scab pressure and dockage policies,” Cowger said.

Fungicides are the other part of the equation, but Cowger cautions that fungicides are tricky. “The first step is you have to monitor your risk because fungicides have to be applied at the right time,” she stressed.

Cowger said national fungicide trials conducted over many years show that the best fungicides offer just 38 to 45 percent control of the disease. “They only reduce the disease partially, and those are the best products,” she said.

The fungicides Proasaro, Caramba and Proline offer the best scab control. “Folicure and Tilt will give you some control, but not as good as the three most effective products,” Cowger said.

The best time to apply fungicides to wheat is at early flowering, when the anthers are just coming out. “You can get a benefit from spraying up to seven days later, and that’s good news. We learned over the last few years that your timing window is not as narrow as we led people  to believe earlier,” she said.

“You’re still going to have a lot of scab even if you spray under the best timing and manner possible if you plant a susceptible variety,” Cowger emphasized. “You have to use both approaches to protect yourself fully in a bad scab year. That’s why we say plant moderately resistant varieties plus use a fungicide when the risk is  high. That’s what we call integrated management. It’s really the only way to tackle this scab problem effectively.”

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