Fusarium also becoming oat growers’ problem

Fusarium head blight, a fungal disease commonly linked to barley and wheat, is “indeed a problem” in Canada’s commercial oat fields, a new study shows.

“You don’t see it in oats as you do in barley or wheat, where the disease is quite obvious in-season,” plant pathologist Andy Tekauz said in a release Monday from the Western Grains Research Foundation (WGRF). “So the likely assumption in the past was that oats weren’t affected by fusarium.”

The WGRF’s endowment fund backed a three-year project involving Tekauz, who works at the federal Cereal Research Centre in Winnipeg, and collaborating researchers.

“We wanted to find out if fusarium is a problem and if so, how big and widespread it was,” he said. “For the three-year project, we sampled a number of fields to find out how many fields had fusarium and which species were involved.”

As part of the project, the team “also wanted to look at oats from Canada and other parts of the world, to see if there was the possibility of improving the resistance level present in our commercial varieties and breeding lines.”

Tekauz was able to demonstrate fusarium head blight is “indeed a problem in commercial oat fields, with more than 75 per cent of the fields surveyed annually affected.” Out of the seed taken from the sample fields, Tekauz said he could isolate fusarium fungi from ten to 15 per cent.

Fusarium can be found in most Manitoba oat fields, he said, and it “tends to be more of a problem in the eastern Prairies and becomes less of a problem as you move further west.”

Unlike wheat, however, in which “95 per cent of the problem” is caused by the species F. graminearum, infections in oats involve the same four species infecting barley crops: F. graminearum, F. poae, F. sporotrichioides and F. avenaceum, Tekauz said.

“We find these four every year in oats when we do our surveys, but their proportion tends to change from year to year. So environment or other factors play a role in determining what levels of these fungi will be found on the seed.”

“Variability” in resistance

Canadian oat varieties and breeding lines, plus material from elsewhere, were then tested for genetic resistance. “Among Canadian oats, there was variability in fusarium head blight resistance. We were also able to identify genetic resistance in lines obtained from other countries, particularly South America,” Tekauz said. Looking for resistance to fusarium head blight based on low accumulation of DON (deoxynivalenol, a mycotoxin found in hog feed made from infected barley) is now a “goal and priority” in Canadian oat breeding programs, the WGRF said.

“The resistance we have identified in the project is currently being used in oat breeding programs in Western Canada, with the aim of improving performance to fusarium head blight and reducing the levels of mycotoxins present in oats,” Tekauz said.

Generally, he said, oats tend to be more resistant than barley or wheat to fusarium. “When we put susceptible wheat and barley varieties as checks into our oat fusarium head blight nurseries, they accumulate more DON than the bulk of the oat varieties.”

Researchers, he said, “would slot most oats into the MR to MS category — moderately resistant to moderately susceptible. In wheat and barley, there’s a whole bunch you put in MS or S.”

Researchers are now working on a ratings system to rank fusarium resistance in current and future oat varieties, the WGRF noted.

“What we’re doing now is screening the western oat co-operative test, to get baseline information on fusarium resistance in our elite breeding lines,” Tekauz said. “We have identified one of (University of Saskatchewan plant scientist) Brian Rossnagel’s lines that was in the coop test in 2006 and 2007 that performed quite well.”


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