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Fusarium conference hears of disease resurgence

Western Canada’s worst crop disease is still a serious issue, researchers say

This was one of the worst years for fusarium head blight in western Canadian spring wheat — a sobering backdrop to the 8th Canadian Workshop on Fusarium Head Blight, held here Nov. 20-22.

More than 200 scientists from Canada, the United States, Germany, England, Australia, Switzerland and beyond reviewed the latest research into fusarium head blight, a yield- and quality-robbing fungal disease.

“The 2016 western Canadian wheat harvest is potentially the worst on record for fusarium head blight (FHB) damage and DON (deoxynivalenol, a mycotoxin) levels in many crop districts,” Canadian National Millers Association president Gordon Harrison told the meeting. “Fusarium damage is 1.5 to five times more than experienced in recent years.”

Fusarium head blight severity on the Prairies.

Fusarium head blight severity on the Prairies.
photo: Canadian Grain Commission

The United States suggests flour contain no more DON than one part per million and some millers and food processors may demand less.

“A significant portion of the (Canada Western Amber) durum (CWAD) wheat harvest (used to make pasta) may be unmarketable as milling grade,” Harrison said.

No. 2 and 3 Canada Western Red Spring wheat (CWRS) — Canada’s top bread-making wheat — also has high levels of DON, he said.

Downgrading could cost Prairie farmers $1 billion in lost revenue, Harrison estimated.

Widespread fusarium head blight damage could cost western Canadian wheat growers an estimated $1 billion, Gordon Harrison, president of the Canadian National Millers Association told the 8th Canadian Workshop on Fusarium Head Blight Nov. 22 in Ottawa. Wheat millers and exporters will suffer too.

Widespread fusarium head blight damage could cost western Canadian wheat growers an estimated $1 billion, Gordon Harrison, president of the Canadian National Millers Association told the 8th Canadian Workshop on Fusarium Head Blight Nov. 22 in Ottawa. Wheat millers and exporters will suffer too.
photo: Allan Dawson

Presumably some of those losses will be offset by crop insurance payments and some farmers might be eligible for aid under AgriStability.

Still it’s a huge economic hit, and not just for farmers, but grain companies that will have less wheat to sell and disappointed customers with long memories.

“The predominant degrading factor this year is fusarium,” Tom Graefenhan, the Canadian Grain Commission’s (CGC) microbiology program manager said on the sidelines of the conference. “I think it is important not to panic. We continue to work on the issues in a co-ordinated and dedicated way.”

Durum wheat, which is more susceptible to FHB than other spring wheats, has been hard hit in southwestern Saskatchewan, where FHB isn’t usually a problem because of drier weather.

Based on preliminary data collected from the CGC’s harvest sample survey, about 40 per cent of the durum wheat still making food grade has been downgraded due to FHB and 25 per cent has been downgraded to below food grade.

CGC data shows the percentage of fusarium-damaged kernels (FDK) — a measure of disease severity — hit a new high in Saskatchewan in 2016.

The severity in Manitoba and Alberta wasn’t as bad as several previous years (see graph).

However, FHB is wider spread in all three provinces than ever before and the trend line is rising.

The combination of more disease — and in many areas greater damage within fields — is making it harder for grain companies to find good wheat to blend with heavier-damaged lots, Graefenhan said.

“It is probably the biggest challenge we’ve had in wheat supply in 21 years of contracting,” Bob Beard, cereal development director for Warburtons, the United Kingdom’s biggest baker, said in an interview on the sidelines of the 3rd Canadian Wheat Symposium Nov. 24. “You cannot use wheat that is over specification (for DON). We are lucky to be working with our farmers and the companies we are and have been able to secure additional supplies to make good the shortfall. But in some areas 60 per cent of our program is not usable, which mirrors probably what you’re seeing elsewhere on the Prairies.”

Warburtons imports around 190,000 tonnes of high-quality, identity-preserved spring wheat from Western Canada annually to blend with a similar volume of U.K. wheat to make bread.

While Warburtons expects to get enough western Canadian wheat to meet its needs in 2016-17, it will be tight, Beard said.

“It’s not all bad. There are some regions where some of our farmers have growing surplus and we have taken that surplus gladly. But in other areas it has been decimated.”

FHB’s spread is worrisome, Harrison said. His member mills need about three million tonnes of domestically produced wheat annually.

More FHB will require more testing and increased costs for millers, he said. Harrison also noted DON hasn’t caused an adverse health problem in Canada in 25 years, and he doesn’t expect any now.

Canada’s grading system uses fusarium-damaged kernels (FDK) as a proxy for DON, but Harrison said since the traditional correlation between the two no longer exists grades should be based on DON levels instead of FDK.

Sheryl Tittlemier, the CGC’s grain safety program manager, says correlation still exists, but given the concerns the CGC will investigate further.

The Alberta Wheat Commission recently suggested grades be based on DON levels, which would require testing at the elevator.

Grain exporters are doing some of that now, as well as testing a portion of loaded cars “to avoid surprises,” Rhyl Doyle, Paterson Global Foods’ director of export trading said on the sidelines of the meeting.

More testing is a good idea, University of Minnesota plant pathologist Ruth Dill-Macky told the meeting, as food markets decrease their tolerance for mycotoxins.

“I think that is going to necessitate us implementing high-speed mycotoxin testing at sales points in order to segregate grain lots in years when we do have lots of fusarium head blight so we can keep the toxins, as best we can, out of grain streams and not be commingling lots that may have different levels of toxin in them,” she said.

FHB is on the rise because of the weather (the disease thrives under warm, moist conditions, increased corn production (corn also produces FHB) and more conservation tillage (FHB persists in wheat residue).

Farmers can’t control the weather and corn and reduced tillage aren’t going away, she said. But there are things farmers can do to manage FHB with an integrated approach. It starts with encouraging farmers to grow wheats that are more FHB tolerant.

“Eliminating susceptible cultivars is really key to preventing this disease from gaining traction,” Dill-Macky said. “And while we can make incredible strides in developing germplasm that has resistance, it’s important for us to remember that there are still varieties out there that are moderately susceptible or more susceptible and it is actually very important for us to find ways to discourage growers from having those, or discourage wheat breeders from releasing those varieties, so we can have varieties that are resistant or moderately resistant on the vast majority of acreage.”

Farmers also have better fungicides to control FHB, including Prosaro, Caramba and Proline. But they must apply them at the right time — within seven days of flowering, using 20 gallons of water per acre to get good coverage. Dill-Macky recommended spraying in the evening or morning so dew can help get the product on the wheat heads.

Farmers also need to know some of those fungicides also contain strobilurins, which control leaf spots, but can increase DON levels, even when applied pre-heading.

Plant breeders and molecular scientists are searching hard for new forms of FHB resistance. The more resistant a variety is the less FHB will be able to colonize its residue, she said.

A wide range of transgenic genes has and is being tested but “we haven’t seen the silver bullet and I don’t think that is really going to happen. However, increased regulation is making it harder to field test genetically modified wheat.”

“I think we have some potential to make progress in this area if we aren’t challenged… by the legal side of doing things,” Dill-Macky said.

About the author

Reporter

Allan Dawson is a reporter with the Manitoba Co-operator based near Miami, Man. Covering agriculture since 1980, Dawson has spent most of his career with the Co-operator except for several years with Farmers’ Independent Weekly and before that a Morden-Winkler area radio station.

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