Use those fusarium maps

Know your risk: fusarium maps offer another metric for spraying decisions

Fusarium infected wheat.

What if farmers could predict Mother Nature’s moods in the growing season? The idea is becoming less and less far-fetched with advances that help producers put a number on disease risk. But fusarium head blight (FHB) risk assessment maps are only one factor among many influencing spraying decisions.

FHB risk assessment maps have been available in Manitoba since 2001 and in Saskatchewan since 2015.

The Manitoba maps are based on data collected by over 70 weather stations operated by Manitoba Agriculture’s agro-meteorology program, and use a model that looks at precipitation and temperature. Saskatchewan’s maps are generated by Weather INnovations (WIN), based on data from the company’s and Environment Canada’s weather networks, and take into account temperature and relative humidity.

In both provinces, the maps are updated daily through June and July.

Bill Gehl, chair of the Saskatchewan Wheat Development Commission (Sask Wheat), says the province’s risk assessment mapping program came about partly due to an awareness of fusarium’s impact in Manitoba.

Where to find the maps?

Farmers in Saskatchewan and Manitoba can access regularly updated fusarium head blight risk maps during the growing season.

In Saskatchewan: On the Sask Wheat website at and viewing “Fusarium Resources.” The maps will be updated again in June.

In Manitoba: Manitoba farmers can see updated maps on the Manitoba Agriculture website at by viewing “Understanding the Manitoba and Saskatchewan Fusarium Head Blight Risk Maps” and choosing the related links.

“Farmers have put a lot of money into fusarium research, and all the farmers around the board table were starting to have issues with it, so certainly the knowledge was there, as well as awareness of the problem in Manitoba,” he says. “It is a very detrimental problem to farmers’ bottom line and we wanted to do as much as possible.”

A “multi-pronged approach”

Barbara Ziesman, Saskatchewan’s provincial specialist in plant disease, says the map indicates disease risk, but in order to be used accurately it has to be used in conjunction with staging.

“The first step is for producers to stage the crop and determine when it will flower,” she says. “If you’re looking at the map 10 days before anthesis, that risk can shift quickly. And your risk assessments might be different for different fields.”

She cautions that FHB needs to be managed with an integrated approach. “The risk assessment maps can help with fungicide application decisions, but those fungicides are only registered for suppression. They will only give us partial control, so we need to look at using some of those other management practices, such as good rotations and the use of resistant varieties.”

Gehl, who farms near Regina, agrees that it’s important to look at fusarium management not just as a spraying issue but as a “multi-pronged approach.” Gehl has abandoned durum production on his farm in favour of better CWRS varieties and adopted agronomic practices that minimize risks.

That’s when the maps kick in, he says, by providing temperature and moisture levels. “We can safely say all the soil in Saskatchewan has Fusarium inoculum in it now, so it’s a question of whether the conditions are correct.”

Last year, Sask Wheat saw 5,000 unique hits on its website during the time it had the maps up. Gehl believes that after last year’s problems producers are learning quickly how to manage the disease.

“There are things a person can do. It’s not all bad news. We do have some very good varieties,” he says.

Ian Nichols, president of WIN, says while the final spraying decision rests with producers, the maps provide a good indication of Fusarium risk in specific areas relative to crop stage. “When you can only grow one crop a year, my recommendation is do not push the risk threshold too far. If there is even some risk indicated by the model, producers may lean toward applying a protective fungicide,” he says. “This crop disease is not forgiving — it is not a condition that you can cure once infected.”

In Manitoba, producers have been dealing with FHB longer than Saskatchewan producers, and especially in eastern and southern Manitoba, “farmers spray preventatively,” says Holly Derksen, field crop pathologist for Manitoba Agriculture.

“At least two thirds of producers, and depending on where you are, sometimes 100 per cent of producers look at the maps, but don’t necessarily use them as part of their spraying decisions,” she says.

The exception is western Manitoba and the Interlake, where producers rely on the maps to spray.

She says southern Manitoba producers have an advantage in terms of mapping resources, as North Dakota uses a model that takes into account host susceptibility. “So if you live close to the border look at those maps,” she says.

This year, Manitoba Agriculture hopes to re-validate its risk assessment model with trials on farm and at its Crop Diversification Centres to measure more variables, including DON and FDK.

These fusarium risk maps below from Saskatchewan during the 2016 growing season show the progression of FHB across the province. (graphics courtesy of Sask Wheat)

About the author


Julienne Isaacs

Julienne Isaacs is a Winnipeg-based freelance writer and editor. Contact her at [email protected]

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