When it comes to fusarium head blight, cereal growers tend to suffer from NIMBY syndrome — ‘not in my backyard.’
“Over the years, we’ve heard many comments that ‘it’s a Manitoba problem — it’ll never be a problem here in Alberta,’” federal research scientist Kelly Turkington said at the recent Agronomy Update conference.
“But in some areas, like southern Alberta, it’s already well established. Other areas, like central Alberta, are probably in a transition period. In the Peace, we have a problem that is fairly limited.”
Since 2007, Alberta has seen a “steady increase” in Fusarium graminearum, the pathogen that causes fusarium head blight in crops such as wheat and barley. The disease was mostly restricted to southern Alberta until 2012, when it spread across the province until reaching a peak — for the time being — in 2014.
“We’re seeing it all throughout central Alberta and through many counties, and there’s quite high levels in southern Alberta,” said Trevor Blois, disease diagnostician for 20/20 Seed Labs.
In 2014, producers saw very high levels of fusarium in their crops, with over 13 per cent of samples submitted to 20/20 Seed Labs testing positive on the plate. Those numbers dropped last year.
“In 2015, we’ve seen a much lower per cent of samples that are testing positive,” said Blois. “This year, we’re down below seven per cent.” For fusarium levels, the drought was a blessing in disguise.
“Fusarium graminearum likes those really moist conditions right around flowering, and it was a very dry year,” Blois told conference attendees. “This year, we had good conditions that Fusarium graminearum didn’t like, but in future years, if those conditions are more moist around flowering, things could be bad.”
And when fusarium hits, it hits hard: since the early 1990s, losses in Canada from fusarium head blight have ranged from $50 million to $300 million annually. “There’s yield loss, there’s reduction in grade, there’s reduction in functional qualities, and there may be implications for where you can market that grain,” said Turkington.
And “there are no silver bullets” when it comes to managing fusarium head blight.
“One of the most frustrating aspects of this disease is that I can’t give you an effective strategy to manage it,” said Turkington. “Even when we use all of the strategies that we have available — resistant varieties, good rotation, fungicide — we still see issues in terms of yield reduction, grade reduction, and mycotoxin contamination, especially when the weather conditions are favourable. It’s a tough target to hit.”
That said, extending rotation is the first step. That’s “not a sexy strategy, but it’s something that we need to start to re-evaluate.” Fusarium builds up in the soil, said Turkington.
“If you have a poor rotation — canola-wheat-canola-wheat, which for me is not a rotation — you’re going to build up that level of infested residue fairly quickly.”
It takes at least two years for infected residue to decompose, he noted. Once you have a longer rotation, resistant varieties are the next step.
And test seed to make sure it’s free from disease. “This is simply to try and limit the potential of introducing this pathogen into your farming operation,” said Turkington.
Seed treatment is a good bet, but it won’t eradicate fusarium, especially if it’s a well-established infection.
“Depending on the level of seed infection that you have and the germination level, seed treatments can be something to look at in ensuring good stand establishment,” said Turkington, adding good stand establishment can reduce the severity of the disease.
Fungicide is a last resort. “The thing that I want to emphasize with fungicides is that they provide suppression at best,” he said. “When you look at the level of control, you need to be realistic in terms of what you expect from a fungicide. For fusarium head blight, it’s 50 per cent control at best.”
The flowering stage is the key time when the pathogen attacks, so producers should be applying fungicide just after the heads have emerged in that crop. “The proper time to apply is when you have about 75 per cent of those heads out of the boot, up until the point where you have 50 per cent of those heads on the main stems starting anthesis (flowering.)”
That’s a narrow window at the best of times, and one that’s especially hard to hit in a wet year. But even with the best management practices, producers have to accept that there’s no knockout blow for fusarium.
This article was originally published in the Alberta Farmer Express