Verticillium stripe has become more prevalent in canola and is not easy to recognize because symptoms mimic other diseases like blackleg or sclerotinia. It’s important for farmers to familiarize themselves with the disease, as it’s expected to become a greater issue moving forward.

WHY IT MATTERS: Tracking historical trends in crop diseases in Alberta can give farmers a head start in preventative measures for present growing seasons.

“It’s here, and it’s going to get worse,” said Michael Harding, crop assurance program lead at Alberta Agriculture and Irrigation, in his disease update for 2025 at the Irrigated Crop Production Update in Lethbridge, Alta.

Segwaying into stripe rust, it has a hard time surviving in open conditions with little snow cover paired with cold temperatures. But, Mother Nature has a way of changing her mind.

“Based on the forecast, I don’t think we’re going to have a lot of stripe rust overwintering in southern Alberta. But, anywhere that there’s snow pack and mild winter conditions, it could survive. So we should keep an eye out for it showing up, and if it shows up early, it could be a real problem, especially in susceptible cultivars,” said Harding.

A dedicated head survey in 2025 showed out of 287 wheat fields processed so far, 28 tested positive for ergot, with the near 10 per cent ratio high compared to previous years.

In one sample, 1.4 per cent of the grain by weight consisted of ergot bodies, indicating a severe problem in that field.

“That is horrible. That sample was a 580 gram sample, and it had over 500 ergot bodies in it. So ergot was a real problem in some fields this year,” said Harding.

The survey is ongoing, with about 300 out of 450 total fields for wheat and barley processed. The final results will be released when the analysis is complete.

“That’s a lot of ergot bodies that are getting returned to the soil at harvest. So there could be some fields that have a lot of ergot. You don’t want to grow an ergot susceptible crop in a field that had lots of it in 2025,” said Harding.

For pulse growers of lentils and peas, if you are seeing root rot and it is getting worse, he recommended finding out if you are dealing with aphanomyces or fusarium or both.

“You are going to march to the drum of the aphanomyces. If it is there, you need to manage the field. When you do that you will also be managing fusarium, so it’s a good idea to do testing,” said Harding.

In 2025, 395 canola fields in Alberta were visited, striving for one per cent of canola acres in every county. There were 98 per cent which showed black-leg symptoms, with 44 per cent of plants affected.

Clubroot was found in eight per cent of fields and two per cent of plants. Sclerotinia affected almost half the fields and eight per cent of plants. Verticillium was minimal at just under one per cent in fields and only a few positive plants.

Zooming the microscope tighter to southern Alberta where irrigated crops are most common, the scouting area featured 90 fields. Black leg was more prominent in southern Alberta fields, but less sclerotinia to go with no club root or verticillium being found in southern Alberta fields.

“We do have irrigated fields in southern Alberta that have club root (historically), but not that many, and it’s really not spreading nearly as quickly in southern Alberta as it is in the other parts of the province,” said Harding.

About 95 per cent of 250 wheat fields surveyed in Alberta in 2025 showed some leaf spot symptoms and 35 per cent of the plants. On average, around 11 per cent of the flag leaf area was covered by leaf spot, with Harding noting some fields had much higher severity.

Stripe rust was found in 5.6 per cent of fields during the initial survey shortly after heading, but spread to 50 per cent of fields in southern Alberta by August.

“When striped rust shows up, it can spread really quickly. We went back about three weeks after this survey and looked at the same fields. The cultivars that had good resistance, you barely can find the stripe and then the susceptible varieties, some of them were devastated by this disease. But, it did show up late enough that it in lot of fields, it wasn’t that big of an issue,” said Harding.

Powdery mildew, wheat streak mosaic and bacterial leaf streak were also observed, with wheat streak mosaic found in just over eight per cent and bacterial leaf streak in four per cent of fields.

The prevalence of these diseases was similar in southern Alberta, though the severity (per cent diseased flag leaf area) was almost half that of the provincial average.

In historical disease trends, the most commonly-occurring disease in canola is black leg, followed by sclerotinia.

“In some years, that’s the second most common. In some years, it’s almost the least common depending on how much rainfall we get, usually around July,” said Harding.

In wheat, fungal leaf spots such as tan spot and septoria are by far the most common. Bacterial leaf streak and wheat streak mosaic have also appeared prominently in some years.

In barley, fungal leaf spots including scald and net blotch are consistently the most widespread. Loose smut and stripe rust are also present.

In pulses, root rot is the most frequently found disease in both pea and lentil fields. Other diseases such as chocolate spot and Alternaria blight are notable in faba bean.

Fusarium has been present as the most consistently common disease in garlic, with Aster yellows and stem and bulb nematode rising in prominence more recently.

Harding encouraged farmers to use disease scouting cards, the Prairie Crop Disease Monitoring Network and the Canada Canola Council of Canada as resources to help battle crop-specific diseases.

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Mike Harding, crop assurance lead for Alberta Agriculture and Irrigation, received a recent call from Nutrien, saying three of its agronomists had found stripe rust near Rosedale, Balzac and Strathmore, according to an Agri-News press release.

Some fields had only a few stripes, while others had significant patches of rust.

The disease affects wheat, barley and triticale.

A fungicide application for susceptible varieties is warranted when approximately one plant per sq. metre is rusted.

Scouting for early detection is critical because once five per cent of the flag leaf area becomes symptomatic in susceptible varieties, it is very challenging to manage with a fungicide.

A fungicide application may not be necessary for resistant varieties.

Once any variety is past anthesis, a fungicide application is not likely to provide much economic benefit.

Harding was at a field school day at Farming Smarter near Lethbridge in late June, talking about stripe rust disease properties.

“This is not a residue-borne disease. This is a disease that doesn’t over-winter here usually. It’s only happened once or twice in the last 25 years,” said Harding.

“It blows in. Spores travel through the air from the Pacific Northwest (for southern Alberta). The years they come early enough, they can cause significant damage, especially in susceptible varieties.”

Stripe rust is managed through resistant cultivars and fungicides. but the chemical must be applied before the flag leaves/upper canopy becomes too heavily colonized.

“Stripe rust is a disease, and powdery mildew as well, that when the conditions are conducive, it’s very explosive and can move quickly through the crop. You have to be scouting for it, aware of it and be ahead of it.”

The Prairie Crop Disease Monitoring Network has disease scouting cards as well as weekly stripe rust risk level updates. It looks at reverse wind trajectories from the areas where stripe rust over-winters.

“For us that’s the Pacific Northwest. It looks for the crop development, the stripe rust development. It looks at when air parcels move over that and come to us, and it produces a speedometer that tells you the relative risk of stripe rust showing up in southern Alberta,” said Harding.

Stripe rust appears as long yellow to orange linear stripes along wheat or barley leaves.

The pathogens of stripe rust are different on barley and wheat, and they can overlap, but are very weak, Harding said.

“The barley pathogen does not cause a lot of disease on wheat and vice versa,” he added.

“Normally, when we see stripe rust, we mostly see it on wheat crops. It can survive on winter wheat when we have a mild winter or a lot of snow cover.”

Given the late appearance of stripe rust in 2025, there may be questions related to crop growth stage, potential yield losses and fungicide timing.

It appeared relatively late on the Prairies in 2024 and the PCDMN posted several updates in relation to these observations and information related to crop growth stage, potential yield losses and fungicide timing.

For information on fungicide options, timings and pre-harvest intervals, consult local provincial crop protection guides and follow label recommendations.

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The province received variable precipitation this spring which had pathologists and producers expecting the arrival of members of the leaf spot complex. However, Kelly Turkington with the Agriculture and Agri-Food Canada Lacombe Research and Development Centre said they may have been scorched by the July heat wave.

That’s no reason for farmers not to scout their fields. A late arrival of stripe rust spores blew into the province in late June, said Turkington. They likely originated in the state of Washington.

“Towards the early part of July there were reports (of stripe rust) out of Warner County and Vulcan County from a consultant and some reports in Lacombe County and then down the Highway Two corridor towards Calgary, both west and east,” he said.

Depending on the point in the season growers seeded, a stripe rust presence in cereal fields may mean a fungicide application, he said. Early-seeded crops may be out of luck from a timing perspective, but producers that seeded later may still have time to tackle the rust.

Those who may still have the chance to spray for stripe rust include those who seeded spring wheat for swath grazing or silage in late May or early June.

“Often we’ve seen in the past our worst stripe rust problems in those late-seeded fields where you might be looking at silage or swath grazing, especially where the variety is highly susceptible,” said Turkington.

Watch Glacier FarmMedia publications for more on this story.

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Other research will look at the value of early fungicide applications, precision breeding, and nitrogen fixation in triticale and wheat.

The funding is channelled through the Ag Funding Consortium, a partnership of 13 organizations established to create a one-window approach for agricultural research and development funding in the province.

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Three agronomists gave an overview of the 2016 cropping season at the SouthWest Agricultural Conference in Ridgetown, outlining challenges and wins for the year.

Leanne Freitag, Cargill’s manager of agronomy for Ontario, outlined challenges with wheat, Steph Kowalski of Agronomy Advantage outlined soybean challenges and Russ Barker of DuPont Pioneer outlined the most unpredictable of 2016 crops: corn.

Ontario had record wheat yields, but that rapidly-growing wheat exposed some crop management gaps.

Freitag said she’s surprised at how many growers don’t apply sulphur on wheat, adding it’s simple to do and inexpensive.

“If you’re putting fertilizer on, make sure sulphur is in there,” she said. As the wheat grew rapidly towards a record yield, more sulphur deficiency symptoms showed up in the Ontario crop.

“Putting on 10-20 lbs. of sulphur is really important, and cheap to put on,” she said.

Where there’s a deficiency, the advantage can be 20 bushels of yield difference, she said. Watch the nitrogen to sulphur ratio: It should be 10:1 to 7:1.

Stripe rust was also an issue in wheat for the first time in memory. The disease overwintered further north than usual, Freitag said, and resulted in more damage than normal.

The greater prevalence of the disease showed which varieties of wheat are resistant and which are not. There is a significant difference, Freitag said, but cautioned not to base variety decisions only on resistance to stripe rust. Plant the best variety for your fields, and spray if required.

“Stripe rust is the biggest yield robber of any of the foliar diseases in wheat,” said Freitag. “It can take 50 per cent or more of your yield.”

Spray when symptoms are seen, she added. “Keeping the flag leaf clean is critical.”

The wheat crop came out of the soft winter with little winter kill, which likely helped the wheat put down roots deep enough that it was able to find enough moisture to pull through the dry summer. Altogether it resulted in a record wheat harvest.

Spider mites everywhere

Soybeans pulled through the summer drought in Ontario in most cases — but not for lack of trying by some insects.

Scouting is the best way to stay ahead of spider mites, Kowalski said. Treat the crop with timely spraying. Be careful what insecticide is used, however, as you don’t want to take out all the beneficial insects, along with the spider mites.

Weed control was a challenge for soybeans in 2016, as there often wasn’t enough moisture to activate pre-emergent herbicides. If the weather is hot and dry, spray early in the morning for systemic herbicides and in the evening for contact herbicides.

Fungicides made sense on soybeans, said Kowalski, as long as you got a timely rain. She says use the whole decisions tree on whether or not to spray fungicides. Don’t just not do it because of weather.

Barker said he worries about blanket recommendations to spray fungicides, due to potential resistance and other overuse issues. “It gives me the heebee-jeebees.”

Good base fertility was important to pulling soybeans through to good yield in 2016.

Unpredictable corn

There were times this growing season that Russ Barker just told farmers to stay out of their corn fields. The fields were just too depressing to visit. He also told them that the fields would yield better than they expected, and he was right about that.

A wise plant breeder once told him that cob size was a poor indicator of potential yield, he said. More important is the depth of kernels and kernel flex. The strongest hybrids will produce a deeper kernel late into the growing season.

“Remember that the growing season is a marathon, not a sprint,” he said.

The response of corn to fungicides is well documented — an average seven to eight bushels per acre advantage, he said. Each farmer has to determine if it makes sense economically on their farm.

Where it does make sense, he said, is on silage corn and corn fed to hogs, as the fungicide reduces mycotoxin load for hogs and dairy farmers need to maximize the quality of feed going into the feed bunk.

Two other unpredicted and especially frustrating problems appeared with the corn harvest last year. The first is the amount of Gibberella ear rot on corn, which surprised the industry by showing up in high levels of infection.

“We’re not a whole lot smarter on Gibberella. We still can’t predict it very well.”

Western bean cutworm (WBC) was also a larger issue as it overwintered further north than usual, and continued its long-term growth into new areas of the province.

The WBC was first seen in Ontario in 2008 and became economically significant in 2010, Freitag said. The problem in 2016 is that it appeared in fields where farmers had scouted and didn’t find egg masses.

“We can’t scout with a high level of assurance that it won’t be an issue,” she said. The industry has to sort out how to monitor for the pest, but the answer likely lies in paying closer attention to trap numbers.

Farmers need to make economic and risk assessment decisions on whether or not to spray for WBC, at least until better biotech solutions for control, such as the Viptera trait, are bred into more widely used hybrids.

— John Greig is a field editor for Glacier FarmMedia based at Ailsa Craig, Ont. Follow him at @jgreig on Twitter.

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However, soggy conditions have also enabled certain disease pressures to rear their ugly head, according to some government specialists.

“Root rot is showing up in peas and lentils,” said Brent Flaten of Saskatchewan Agriculture in Moose Jaw.

In addition to the rot, the fields were also feeling the effects of pythium and water mould (aphanomyces euteiches).

In a few cases, some lentil fields were virtually wiped out, though most are OK — “kind of hit-and-miss depending on how much rain or water the field retained,” he said.

Flaten said he is also fielding questions from producers wondering whether to spray for sclerotinia in canola or leaf diseases.

“There’s probably even more acres where people are worried about (fusarium) head blight or sclerotinia than the root rot.”

Issues are similar in Manitoba, with both fusarium and root rot cited as problems.

However, provincial field crop pathologist Pratisara Bajracharya said there is another familiar name working its way in from the U.S.

“Leaf rust is in some Manitoba locations as well as near the Montana and North Dakota border,” she said.

As a result, Bajracharya is asking producers to scout their fields in the lower canopy to look for both leaf rust as well as stripe rust.

“That is for wheat, barley and small-grain cereal crops,” she said.

Root rot has been an issue for soybeans, while one canola field near Carman, Man. had a bit of blackleg.

“In general, lots of different diseases were showing up this year compared to other years,” she said.

Both specialists agree further rains will only exacerbate the problem.

— Dave Sims writes for Commodity News Service Canada, a Winnipeg company specializing in grain and commodity market reporting. Follow CNS Canada at @CNSCanada on Twitter.

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For now, the immediate challenge before growers is to get out and scout their wheat fields. According to Dale Cowan, senior agronomist with Agris Co-operative, the worst-hit region for stripe rust at week’s end is west of Thamesville in Chatham-Kent, south of Highway 401 and down along the Lake Erie shoreline into Essex County.

This is the region, Cowan said, where the rust spores were first blown in and deposited, and where the disease is most advanced.

But there have been additional sightings farther north, even into Grey and Bruce counties. And no matter where it’s found, growers need to act quickly to avoid significant losses in yield.

“It’s at the point where you want to keep the flag leaf clean because it produces 70 per cent of the yield, and it’s sporulating very quickly and moving very fast,” said Cowan.

“The next stage we’d consider a fungicide would be T3 (head stage), so what we’re advising is that you have to keep the flag leaf clean with a T2 (flag leaf) fungicide.”

The problem began farther south in the U.S. — and Cowan noted it was already 400 miles further north into Kentucky than it normally should have been.

Even for a grower with crops three days away from a head spray (at T3, growth stages 59 to 65), the disease is advancing so quickly that waiting those three days to save money could cost him or her 50 per cent of a field.

In the past three days, Twitter has seen a variety of photos depicting the extent of the spread of the disease. One individual photographed his lower legs and boot tops covered in yellow-orange spores, just from walking through a field. Another shows the soil between rows with the same yellow-orange colouration.

“Once the flag leaf is gone, you’re going to take a 50 to 60 per cent yield hit,” said Cowan. “If you don’t spray the flag leaf now and you’re going to wait for T3, there’ll be nothing worth protecting even three or four days from now. If you’re a week away from heading, you have to make two passes through the field or you just won’t have anything worth spraying at T3.”

The fungicides a grower would use for T1 (tiller) or T2 (flag leaf) cannot be used if the awns are showing or the heads emerging, Cowan warned. Those particular fungicides carry a strobilurin, which will increase levels of deoxynivalenol (DON) — and the risk of DON infection is extremely high, as well.

“We have this situation where we have rust, where we can lose half our yield, or DON, which will make the crop unsalable,” Cowan said, adding that neither is a great option.

“Those are your two choices, so you can’t just sit there and ignore this crop because you won’t have a wheat crop if you’re badly infected. And the first step is you have to get out and scout your fields!”

— Ralph Pearce is a field editor for Country Guide at St. Marys, Ont. Follow him at @arpee_ag on Twitter.

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The diseases, which generally target cereal crops, were thought to have blown up from the northern U.S. in late spring. Fields near Carman and Killarney both tested positive for rust in winter and spring wheat.

Recent warm weather, however, appears to have dealt the two rusts a deadly blow.

“Not with this heat — rust doesn’t enjoy 30 C days, even though we’ve had precipitation; it’s just been too hot,” said Pam de Rocquigny of Manitoba Agriculture, Food and Rural Development in Carman.

She credited producers in the affected areas for scouting fields and applying fungicides where needed, as the main reasons for the diseases’ departure.

The ag department’s focus now shifts to fusarium head blight, she said, as now is the time the crops traditionally show symptoms.

“Usually about 21 days after flowering — that’s when you start to see the symptoms on the wheat heads,” she said.

Already, a few stands of winter wheat have exhibited signs of fusarium.

Infection generally occurs at the flowering stage, so the timeline for applying fungicide for suppression has passed, de Rocquigny said.

“But we haven’t sampled enough fields yet. We expect to know more in a week or so.”

— Dave Sims writes for Commodity News Service Canada, a Winnipeg company specializing in grain and commodity market reporting.

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Stripe rust and leaf rust appear to have blown in from the United States.

Pam de Rocquigny of Manitoba’s agriculture department said the two rust strains were observed at extremely low severity in MCVET winter wheat plots at Carman. Also, a patch of stripe rust was found in a winter wheat field southwest of Killarney.

“Stripe and leaf are just across the border from us, so I guess it was just a matter of time until we started to see those diseases appear here in Manitoba.”

Rust diseases are sporadic on a year-to-year basis, she said. Right now is an opportune time for them, though, as winter wheat is flowering and spring wheat is advancing at a steady rate.

“Some of it’s in the flag leaf, so we’re 10 days away from that crop heading out and starting to flower,” she said, adding farmers should definitely be scouting their cereal crops.

Fortunately, both strains of rust can be managed with fungicides and are still relatively scarce, according to de Rocquigny.

“I don’t think there’s a cause for real concern at this point.”

— Dave Sims writes for Commodity News Service Canada, a Winnipeg company specializing in grain and commodity market reporting.

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Eight fields surveyed in the County of Lethbridge had no signs of stripe rust. Of the six fields surveyed in the County of Warner, three fields had trace incidence of stripe rust (< 1 infected per m2).

While two fields had no signs of stripe rust, one of the fields had an average of approximately four infected plants per square meter with about two percent of the surface of infected leaves having symptoms of stripe rust. Along one edge of this field, incidence was quite a bit higher at about 10 infected plants/ m2  .

Of the five fields surveyed in the County of Cardston, no fields showed symptoms of stripe rust.

Click here for a cereal rust/wind trajectory event update.

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