Fusarium head blight continued its devastating march across Alberta last summer, and shows no sign of slowing down.
“It’s become something that’s well established in the southern part of the province, and the situation is starting to change elsewhere in the province, especially central and northern Alberta,” said Kelly Turkington, a research scientist with Agriculture and Agri-Food Canada.
“It’s becoming more widespread, and that’s definitely a concern going forward as far as managing it.”
20/20 Seed Labs is still processing 2016 samples of wheat and barley but so far, there’s both a higher rate of infection and more severe infection, said disease diagnostician Trevor Blois.
“So far this year, we’re seeing 23.4 per cent of samples that are testing positive in Alberta across all crop types,” he said. “Compare that to last year, which was really dry, we saw 5.9 per cent of samples testing positive.”
The highest incidence of infection previously was in 2014 — another wet year — when 13.3 per cent of samples tested positive.
“(Last year) is pretty much exactly 10 per cent higher than 2014, and that’s a significant jump,” said Blois.
The per cent of infected kernels in positive samples is also rising, he added.
“In 2015, we had fewer positives, but the per cent infection was still one of the highest that we saw. The per cent infection was 2.65 per cent, and this year, it’s 2.96 per cent,” he said.
“It looks like a small difference but looking at a lot of samples, it all adds up.”
Fusarium head blight has also spread to other parts of the province where it has not previously been seen.
“The south has always been the epicentre for fusarium graminearum, but you can see as time goes on that it has spread into other regions,” said Blois. “Once it gains a foothold, it just spreads.”
Southern Alberta still has the highest incidence of disease, with 63 per cent of samples from the County of Lethbridge and 86 per cent of samples from the Municipal District of Taber testing positive. (The percentage of infected kernels in Taber samples is also very high at 4.28 per cent.)
But farmers in other parts of the province are starting to be hit from two fronts — the gradual spread north from southern Alberta and west from Saskatchewan.
“Across all of central Alberta now, we’re seeing more infected samples than we’ve historically ever seen, and we’re seeing it spread into other regions,” said Blois. “Up in the Peace Country, we’re getting quite a few positives.”
Given the higher levels of inoculum, fusarium’s spread seems inevitable.
“The pathogen has to be there, of course, but having wetter years allows it to spread quicker and gain a foothold in areas that it hasn’t been before,” said Blois. “If conditions are drier in 2017, we could see it go down, but over the long term, we’re going to see an increase in both the number of samples that are testing positive and in the average per cent of infection.”
That’s the story that’s been playing out in our neighbours to the east, said Blois.
“In 2007, (Manitoba and Saskatchewan) were more similar to us, but now I think around 96 per cent of samples from Manitoba are testing positive, and Saskatchewan is somewhere between 70 and 80 per cent,” he said, adding one in five kernels coming from Manitoba has fusarium graminearum.
“They’re much wetter than we are, but it’s a look at what could be. That’s a long way down the line, but they’re basically the worst-case scenario.”
It’s “very devastating” for farmers in those provinces, said Turkington.
“In many areas of Saskatchewan over the last four or five years, they’ve been doing everything that’s being recommended by experts. They’re using resistant varieties, they’re spraying with a fungicide, and they’re not growing wheat on wheat,” he said.
“They do all those things, and yet they still get hammered as far as grade reduction. They easily go from a No. 1 to a No. 2 to a No. 3. It’s a yield reduction but more importantly, it’s a grade reduction.”
Fusarium graminearum produces DON (deoxynivalenol, commonly referred to as vomitoxin), which makes wheat unfit for milling and sees barley rejected for malt or even for feed.
That may force producers to “look at other cropping options,” said Turkington.
“That has occurred elsewhere, where producers have turned to soybean or corn or other crops because they simply are concerned that they can’t be successful growing wheat or barley that is going to meet the quality specs that the end-users have,” he said.
“It becomes a matter of being at the mercy of the weather conditions each year.”
Farmers in Saskatchewan and Manitoba have weather-based risk forecast maps to help determine when to spray, and a similar forecast map should be ready for next summer. But producers still need to be regularly scouting for the disease.
Wheat-canola doesn’t work
They also need to take “an integrated approach to fighting it,” said Turkington. “Producers need to try and utilize as many of the tools that are out there to try and mitigate it,” he said.
Fungicides can help suppress the disease, but producers should expect to see only 50 to 60 per cent control at best.
“In many cases, it can be much lower,” said Turkington.
Resistance has improved in many cereal varieties, but it’s been incremental, he added.
“Where you have conducive conditions in mid-June through July and you have well-established inoculum in residue, those resistant varieties are still going to get hit hard, and you may see significant downgrading and mycotoxin contamination,” he said.
The best thing that producers can do to manage fusarium head blight is lengthen their rotations.
“Probably one of the biggest factors in terms of building the amount of infested residue is, unfortunately, the rotations that we have,” Turkington said of the typical canola-cereal rotation seen in many parts of the Prairies.
“That single year of a non-host crop between your cereal crops is simply not enough for decomposition of the infested residue that’s there.”
Producers need at least two years between susceptible crops, but three to four years is even better, he said. “We can start to drive down the amount of infested residue over the long term — and that may take 10 to 15 years — but it will help to reduce the amount of infested residue.”
But first, producers will need to recognize that fusarium is now an Alberta issue.
“Don’t assume that it’s only a problem for other people or other provinces. It can be an issue on your own operation,” said Turkington. “Producers can’t take an NIMBY approach (not in my backyard), it’s not a problem for me. It’s something you need to actively be scouting for.”