If the 2010 growing season was any indication, disease management needs to be one of the top things on growers’ lists if they are going to have a great wheat crop, says an Ohio State University Extension plant pathologist.
“We had everything this year — head scab and vomitoxin, Stagonospora leaf and glume blotch, powdery mildew, leaf rust, head smut and cereal leaf beetle, plus a very hot late spring and early summer,” says Pierce Paul, a small grains specialist. “The more aggressive growers were with disease management, the better the wheat.
"Some folks were just lucky, but in general, those who had resistant varieties planted and applied a fungicide at the right time saw better yields and test weights, and had lower levels of vomitoxin.”
The biggest problem this year for growers was head scab and vomitoxin contamination of grain, with incidence ranging anywhere from 3% to 60% head scab, and vomitoxin from less than 1 part per million to 18 parts per million.
“Both Stagonospora and powdery mildew were also severe, with a severity score of 7 out of 10 this year,” Paul says. “Diseases combined with a short grain-fill period resulted in low to moderate yield and grain quality, with average yield ranging from 40 to 90 bushels per acre and test weight from 45 to 60 pounds per bushel.”
Despite the challenges this year with wheat, Paul says there are plenty of positives to take away from the growing season.
“The good news is rarely did we see all of the disease problems in the same fields. As is usually the case, some fields still escaped most of these problems,” Paul says. “This is largely because those fields were either planted with resistant varieties, were planted after soybeans, treated with a fungicide at the right time, flowered before or after the rains or various combinations of the aforementioned.”
He notes that even in areas where scab levels were high, some of the fields with the lowest levels of vomitoxin and highest yields and test weights were those that received a fungicide application at flowering.
“Similarly, fields treated for Stagonospora also had better grain yield and quality than fields left untreated,” Paul says. “Combining variety resistance with fungicides added a few more bushels to yield and pounds to test weight.”
Another positive from this season was the success of the Fusarium Head Blight Risk Assessment Tool in timely alerting growers to potential head scab risk.
“We did have more scab in 2010 than we had in 2009 and the risk tool clearly indicated that was going to be the case,” Paul says.
As growers plan for next year’s wheat crop, Paul reminds them to keep in mind that if weather conditions are right, disease is likely to develop.
“The lesson learned this year is that if the weather conditions are favorable, diseases can take a bite out of both yield and quality of even our highest-yielding varieties,” Paul says. “We will almost always get some powdery mildew. If it's wet and humid during the early and middle part of the season, we will certainly see Stagonospoa and Septoria leaf blotch. If it's wet and humid during flowering, we will more than likely see head scab.”
But, he adds, there are steps growers can take to minimize the risks:
- Use the head scab forecasting model to help detect early risk. “If there is a high risk for scab, risk for Stagonospora glume blotch also tends to be high,” Paul says.
- Manage foliar diseases with resistant varieties or with a well-timed fungicide application if the variety is susceptible, with a percent control as high as 90%. “Resistance must be combined with a fungicide application at flowering to achieve the best results in terms of scab and vomitoxin control,” Paul says. “Since it's almost impossible to find a variety that is resistant to scab, Stagonospora, powdery mildew and rust and still yield well, we would suggest that priority be given to scab resistance.”
- Plant resistant varieties with different flowering dates, or maturities, to reduce the chance of an entire field being affected by a disease.
Despite the management challenges, Paul emphasizes that wheat remains an important crop to include in a crop rotation. It improves corn and soybean performance, has soil and other environmental benefits and helps to keep corn and soybean insect and disease pressures to a minimum.
“Wheat is no longer the low-yielding crop it was 15 years ago. If managed properly, most of our current varieties can yield well above our state average,” Paul says.