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New control options help growers manage fusarium head blight

Fusarium head blight (FHB) is one of the biggest challenges facing Ontario wheat growers because of its capacity to damage wheat quality. That is according to Peter Johnson, the Ontario Ministry of Agriculture, Food and Rural Affairs cereal specialist, who says Fusarium is always present somewhere in the province in any given year. Johnson reports that “scouting backwards” from heading enables growers to decide when to apply a fungicide in an attempt to reduce disease levels.


November 30, 1999
By TOP CROP MANAGER

Topics

Fusarium head blight (FHB) is one of the biggest challenges facing Ontario wheat growers because of its capacity to damage wheat quality. That is according to Peter Johnson, the Ontario Ministry of Agriculture, Food and Rural Affairs cereal specialist, who says Fusarium is always present somewhere in the province in any given year. Johnson reports that “scouting backwards” from heading enables growers to decide when to apply a fungicide in an attempt to reduce disease levels.

Recent fungicide registrations are also providing wheat growers with new control options. “Fusarium head blight has been most prevalent in spring wheat during the past three years, but has been devastating in winter wheat, too, in certain hot spots such as Brantford and Paris,” Johnson says. “Fusarium head blight can quickly devalue a crop from milling to feed grade, or worse. And at infestation levels of 10 percent or more, it is almost impossible to market the crop at any price.” The level of Fusarium infestation is dependent on the weather conditions three to seven days prior to heading, and two to 10 days after the wheat heads have emerged. “Fungicide applications for fusarium head blight are most effective during Day 2 to Day 4, and a crop will never all head on the same day,” Johnson says. “Projecting when a crop will head out, and scouting backwards, can help growers get the application timing right to maximize the value of their fungicide application.”

Ontario: Fusarium epicentre
Fusarium head blight causes wheat kernels to shrivel and contaminates the remaining grain with mycotoxins.  These are primarily deoxynivalenol (DON), which inhibits protein biosynthesis; and zearalenone, an estrogenic mycotoxin. These toxins cause vomiting, liver damage and reproductive defects in livestock, and can be harmful to humans through contaminated food. Despite efforts to find Fusarium-resistant genes, no completely resistant wheat variety is currently available. “Ontario is the epicentre of Fusarium in North America,” Johnson adds. “Weather conditions here lend themselves to it. And, Fusarium is not the only disease with which wheat growers must contend. Other major diseases include tan spot, septoria leaf spot, rust diseases, and powdery mildew, all of which can impact yields. Timely fungicide applications can help growers manage grain quality issues associated with fusarium head blight and control leaf diseases.”

Johnson says the value of foliar fungicide applications in wheat depends upon a number of factors, including, the grower’s appetite for risk; varietal differences, weather patterns and wheat prices. Understanding the true effects of disease on wheat yields and grain quality, and the economic return from timely fungicide use, can help farmers better understand when an investment in foliar fungicide for wheat is warranted.

A marketing perspective
Crosby Devitt is manager of Research and Market Development for the Grain Farmers of Ontario. Devitt says that chemical testing for DON contamination provides twice the level of scrutiny of visual testing, which was the standard screening practice just a few years ago. “Discounts for Fusarium vary according to grain market conditions, but they can be significant,” Devitt says. “Because corn and wheat are the primary choices for livestock feed, fluctuations in corn prices influence feed grade prices for wheat in Ontario, and subsequent discounts. Two consistent factors, though, are the annual presence of Fusarium somewhere in Ontario and the ease with which wheat can be downgraded from milling to feed grade, or worse.”

Wheat prices are based on farmers supplying wheat that is suitable for milling into flour for human consumption. When Fusarium is above a level acceptable for flour milling, a discount is applied to the price. The discounts vary based on the level of Fusarium and market conditions and are usually applied as a discount from the milling wheat price. Devitt advises growers to use all of the tools available to ensure that they maximize both the value of their crop and its economic return. “Crop rotation and variety selection, for example, can help to prevent fusarium head blight. Wise use of fungicides can help to protect the quality and value of your crop, and the price you receive at the elevator.”

New Group 3 fungicide available for Fusarium  
In 2010, BASF Canada received Pest Management Regulatory Agency (PMRA) registration for Caramba fungicide, a new systemic fungicide for use on wheat, oats, barley and rye. Its active ingredient is metconazole, part of the triazole (Group 3) family which has protective activity on a number of foliar diseases in a range of crops, including superior fusarium head blight management.

Ian Greydanus grows 700 acres of soft white and soft red winter wheat in Wicklow, Ontario. Fusarium is a consistent threat on his farm, although not every year, with leaf disease being more of an annual challenge. Applying a fungicide labelled for both types of diseases helps Greydanus proactively manage FHB and control leaf disease, he says. He weighs the cost of the fungicide application against the anticipated yield and quality loss to develop a return on investment calculation for his acres. “We scout and plan to apply fungicide every season,” Greydanus says. “We compared Caramba with Folicur in a trial two years ago and we could see a positive, visual difference where Caramba was applied. In a Fusarium year, our return on investment from a fungicide application is eight-to-one. Even when only leaf diseases are present, we’re still getting a three-to-one return. Wheat disease protection is a priority for us. We’ve tried ‘nothing,’ and we know what that looks like.”