A big culprit was a sprayer model Dion bought on the promise of exceptional weed control with only 2.75 gallons per acre of water and 75 per cent of the recommended herbicide rate. Horse feathers.

“I realized years later that it was a sales pitch, and it was the beginning of my problems with wild oats,” says Dion, who farms with his son, Tarren, near Donnelly, Alta., in the Peace River region.

The same herbicide groups applied “over and over again” also contributed, he says, and so did a change in their crop rotation. The Dions used to produce alfalfa for the export processor at Falher. The perennial crop stayed in production for three or four years, providing exceptional weed competition. Then the processor closed, and alfalfa went out of the rotation. The rotation is now primarily canola and wheat, with some peas.

Dion then strung together another short list of competition killers that allowed the resistant population to explode. Peas drowned out during a couple of wet years, and wild oats filled all those empty spaces. Same thing with seeder misses. He also recalls the times the sprayer was “not purged properly” and applied only water for several acres.

All these activities, stretched over 20 years, produced a massive seed bank of wild oats with resistance to a long list of herbicides.

Test results

Calvin Yoder, a specialist with the local research organization SARDA and Peace Region Forage Seed Association, collected wild oat seeds on that field in 2022 and 2023. He sent them to a lab for herbicide-resistance testing.

“Never make assumptions,” Yoder says. “Lab testing is crucial for developing a long-term plan in terms of future crops and herbicide options.”

The tests revealed a field of super-powered wild oats.

Results from 2022:

• 97 per cent of sampled wild oats were resistant to Group 1-fop chemistries (e.g. actives in Puma Advance and Assure II)

• 72 per cent were resistant to Group 1 pinoxaden (e.g. active ingredient in Axial)

• 70 per cent were resistant to Group 1 tralkoxydim (e.g. Achieve L)

• 37 per cent were resistant to Group 1 clethodim (e.g. Centurion)

• 98 per cent were resistant to Group 2 flucarbazone (e.g. Everest)

Results from 2023:

• 100 per cent of sampled wild oats were resistant to Group 1-fop chemistries

• 76 per cent were resistant to pinoxaden

• 28 per cent were resistant to clethodim

• 86 per cent were resistant to flucarbazone

• 87 per cent were resistant to Group 2 thiencarbazone (e.g. Velocity)

• 86 per cent were resistant to Group 2 pyroxsulam (e.g. Simplicity)

Many key tools were now off the table, but at least the Dions knew what they were up against.

Like a strict fitness routine

So where does a farmer begin to exorcise those demons?

Dion now invests serious time and money in herbicide-resistant weed management, using expert help from SARDA staff as well as Kristina Polziehn, owner of Axiom Agronomy. She is the weed management equivalent of a fitness instructor.

“If you want results, make a plan and set goals,” Polziehn says. “It can take seven to 10 years to fix these fields. You can have great results after a couple of years, but you have to stay on top of it.”

A field can quickly backslide if you give weeds any shot to set seed in big numbers.

Fall herbicide is a good proactive step, Polziehn says, and it requires a firm commitment to next year’s rotation. Fall herbicide choices have to mesh with the following crop. Canola seedlings, for example, tolerate only a specific few herbicides applied in the fall.

If the Dions decide on wheat for next year, Polziehn would recommend a fall application of Focus, a herbicide that includes Group 15 pyroxasulfone and Group 14 carfentrazone-ethyl.

“The Group 15 product at the 136-millilitres-per-acre rate has good residual on their soil type for wild oat in the spring,” Polziehn says. The Dions have not used these actives on that field, she adds.

If the Dions decide on faba beans or peas, crops they grow less often due to markets (faba beans) and aphanomyces (peas), they could use Edge in the fall.

In the spring, just before seeding, Dion has also tried Avadex.

“It works, but not always 100 per cent,” he says. “It works best with blackened soil, little to no straw and half an inch of rain right after application.”

To improve results, he harrows in the fall and again in the spring before applying Avadex.

Use canola HR systems to their full advantage

With Liberty Link canola, Polziehn encourages farmers to make their second pass with higher rates of Liberty and full rates of clethodim. The second application is often a challenge, she says, when spraying season is long and farmers are tired and burned out.

“Some clients always budget for a second pass to ensure weed seed production is managed, despite no yield advantage,” Polziehn says.

When growers use TruFlex, Polziehn encourages them to take full advantage of the multiple application option. She says the TruFlex system is great for herbicide-resistant wild oat management.

The Dions grew TruFlex canola on the 600-acre field in 2025. They sprayed it four times and it was “super clean,” Dion says, “but Tarren was getting sick of spraying that field.”

Is it possible to select for glyphosate-resistant wild oats? “Yeah, probably,” Dion says. “But I’m not worried about it at this time.”

Yoder adds a few specific tips for TruFlex: Use the 333 ml rate over multiple applications, and use higher water volumes — like 10 gallons per acre — when the canola is to starting to canopy.

Bayer advises that applications should be 10 days apart; the total rate for the year cannot exceed 1.33 litres per acre total; and do not apply beyond first flower. The company adds that the 333 ml rate is appropriate for wild oats, but perhaps not all weeds. Know the weed spectrum and apply appropriate rates for those weeds. Finally, Bayer notes that canola cultivars with stacked Liberty Link and TruFlex offer added opportunity to rotate herbicides.

“Multiple applications might be expensive in the short term but will pay dividends in the long term,” Yoder says. “TruFlex canola provides the best opportunity to start managing fields with high levels of herbicide-resistant wild oats, so take advantage of the opportunity.”

Part of the problem in 2025 was a dry start that slowed canola crop establishment in the field. Canola emerged in patches, with some three to four weeks later than the first emerged plants.

“The wild oats kept filling in those open spaces with new flushes,” says Dion.

Polziehn hopes this aggressive approach with the TruFlex system in 2025 will reduce the Dions’ wild oat numbers and eliminate some of the biotypes with broad-spectrum resistance. She plans to test seed from random escapes. She captures samples with an insect sweep net when seeds are mature and just about to drop.

Polziehn recommends weed seed tests to identify the resistance biotypes in a field. She sends seed samples to the Ag-Quest lab in Manitoba (see sidebar.) Tests are specific to each herbicide active ingredient. At $135 per test, testing numerous active ingredients can add up, but an accurate picture of products that work will lead to improved weed control decisions.

Scout closely

While testing is an important step to know what products should work, growers also need to scout before spraying and again a few weeks afterward to see how the herbicides performed.

Performance is not always as obvious as you might think. One of Polziehn’s farmer clients applied Edge last fall to a field planned for pulses this year, yet the crop still had a lot of wild oats. Turns out these wild oats were all germinating from below the herbicide layer.

“These were very determined wild oats,” she says. The fact they germinated and the farmer sprayed them in-crop did take a step toward reducing the wild oat seed bank — an important step in the long-term management program.

Expand the circle with spot sprays

Farmers may be inclined to spot-manage a patch of herbicide-resistant weeds, especially when soil-incorporated herbicides are $30 per acre.

Polziehn has specific concerns and recommendations for spot applications: Plants often get missed if the target area is too small, and those few misses can refresh the seed bank and perpetuate the problem.

Instead, she makes the spray area much larger than the patch. If the patch is two acres, she will spray 15 to 20 acres around it, then scout after to see that everything was controlled.

Be determined

Once a population of herbicide-resistant weeds has taken over a field, farmers need a long-term plan and a gym-rat level of patience and determination.

Dion knows they’re in for the long haul. “The wild oat seed bank in that field is banked hard,” he says.

The post Farm gets aggressive on wall-to-wall resistant wild oats appeared first on Grainews.

Idaho potato farmer Blake Matthews caught the attention of Nature United with his crop-nutrition-first approach to pest management.

Matthews grows 3,000 acres of irrigated annual crops, including 400 to 500 acres of potatoes, the same in sugar beets, and the rest split among corn, barley and wheat. Over the past five-plus years, the farm applied one in-season fungicide to potatoes and only last year applied localized spray for insects — specifically, grasshoppers.

This minimal pesticide requirement may sound unbelievable, especially to other potato growers. “We do make some big claims,” Matthews says.

In addition to lowering pesticide use and synthetic fertilizer use, Matthews also says soil organic matter across the farm is in the three to four per cent range, up from a range from 0.7 to two before he put the focus on soil health and plant nutrition.

These numbers, in turn, caught the attention of Brad Johnson, Idaho agriculture strategy manager for Nature United (called The Nature Conservancy in the U.S.). Johnson says the non-government organization’s goal is to help modern agriculture become more sustainable. “We want to keep all tools, but seek judicious respectful use of pesticide products,” Johnson says.

Matthews Land and Cattle is one of Johnson’s demonstration farms.

Potatoes are an input-intensive crop, Johnson says. Potato crops often get soil fumigation for nematodes, along with fungicides and insecticides throughout the growing season. Matthews has all but eliminated these applications, Johnson says.

What’s more, Johnson adds, Matthews has also reduced tillage from four or five passes down to two passes, and reduced overall water use by 18 to 20 per cent.

Matthews “lets biology run the system,” Johnson says.

The core of the system is a soil health plan from long-time local agronomist Jared Cook. “Diseases and insects attack weak plants,” says Cook, agronomic specialist and sales consultant with Rocky Mountain Agronomics in Idaho. “And weakness is often related to nutrition.”

Cook has been working with Matthews and his family business, Matthews Land and Cattle, for 14 years. A key part of the soil health plan is manure compost from dairies and cattle feedlots, which improves organic matter and reduces the need for other fertilizer sources. Cook also prescribes two broad-spectrum hormones, which he won’t share because they are, he says, part of his competitive advantage.

For nutrients, Cook wants balance. He doesn’t want nitrogen availability to get ahead of the other nutrients. “In that situation, nitrogen robs yield,” he says. (Later in this article, Western Canadian crop nutrition experts comment that this can be true for potatoes and wheat, but perhaps not canola.)

“My game is to prioritize mineral nutrition, then use hormones to drive greater response,” Cook says.

The author told Cook during their interview that he usually looks at hormones and biologicals with a degree of skepticism. Cook supports that skepticism. “My approach has changed,” he says. “Ten years ago we didn’t have as many players in this space and I had almost complete trust. Now growers need a trusted advisory team.”

Cook emphasizes his methodical approach to nutrient decisions for all crops, using weekly and biweekly plant sap analysis of new and old leaves in combination with rapid soil testing. For Matthews, his in-season top-ups run through the irrigation system while watering.

With traditional tissue tests taken from new growth only, “you actually never know where the nutrient is coming from,” Cook says. “It could and should be from roots like normal or it could be from old leaves, where mobile nutrients are leaving the old growth to support new growth. We know yield is optimized when you can hold the plants’ old growth and new growth leaf nutrient density to a tight tolerance between them.”

Without accurate diagnosis, input use is “a guessing game and we just don’t need to be guessing,” Cook says. “These new advances in plant testing methods give us the edge in making the right decisions.”

Of course the final question is: does this intense level of management pay?

“We haven’t seen anything really for a yield change. We have, however, seen our quality go up in many different aspects,” Matthews says. “As far as the spend goes, for the most part, we’ve just traded dollars. We’ve replaced fertility with the compost, and replaced fungicides, insecticides and fumigants with nutritionals and biologicals. Overall, though, we probably save about $100 per acre from what our old program used to be.”

Reaching out to Prairie expertise

For many farms, ideal fertilizer management is simple: use soil tests to identify the right rate based on the farm’s yield target. Then choose nutrient sources that meet crop needs at the lowest cost and the greatest logistical efficiency. Manure can be a great nutrient source and organic matter booster when available and when applied based on nutrient analysis.

With these basics established, farms could dig deeper — in the way Matthews has — and hire an experienced agronomist to develop a more comprehensive plan.

Jared Cook outlines the four practices at the heart of his program:

• Balanced nutrition can make plants more resilient to insects and disease, and reduce the need for fungicides and insecticides.
• If farms put the primary focus on higher nitrogen rates, that extra nitrogen — when other nutrients are out of balance — can actually rob yields.
• Plants with correct nutrition have higher sugars (brix) and more secondary metabolites – compounds plants use to defend themselves.
• There are 16 essential elements, each with a specific mode of action. We need to pay closer attention to micros.

Do those four practices work for the common crops and farm systems in Western Canada? We polled western Canadian specialists — crop nutrition researchers, experienced agronomists and plant physiologists — to see what they thought of Cook’s four practices.

Balanced nutrition can make plants more resilient to insects and disease, and reduce the need for fungicides and insecticides. Is this true?

“It’s true, a crop with balanced nutrients can better tackle diseases and insects,” says Raju Soolanayakanahally, a plant physiologist with Agriculture and Agri-Food Canada in Saskatoon. “Balanced nutrients permit vigorous growth, thus providing active immunity as a result of increase phytonutrient, protein and lipid synthesis. Apart, photosynthesis will operate at its peak under balanced nutrition and adequate soil moisture. So if pests attack the plant, the plant can divert resources to tackle biotic stress without compromising yields.”

In general, experts agree healthy plants will be hardier plants. However, that does not mean healthy plants are immune to disease.

“Higher fertility leads to more vegetative growth, and lush canopies create a microclimate conducive for higher disease severity,” says Mike Harding, crop assurance lead for Alberta Agriculture and Irrigation. “In many cases the conditions for maximum plant growth are also the conditions for maximum disease potential.”

Chris Manchur, agronomy specialist with the Canola Council of Canada, adds, “We all know sclerotinia risk is higher in high-fertility environments.”

Jason Voogt says crop resilience to disease or insect pressure has “more to do with genetics.” The owner and lead agronomist with Field 2 Field Agronomy at Miami, Man. gives an example: “We had 200-bu./ac. oat crops in 2024. I would say those oats didn’t lack anything, yet we would have had major losses to crown rust had we not sprayed a fungicide this year.”

Ross McKenzie, retired agronomy research scientist with Alberta Agriculture, agrees nutrition is one path but not the only path to hardier plants. “A number of good agronomic factors, including soil fertility and fertilizer management, increase crop health, improve yield potential and help to reduce the impacts of diseases and/or insect pressure,” he says. “Probably the most notable is earlier seeding and slightly higher seeding rates.”

Lyle Cowell, Nutrien senior agronomist based at Tisdale, Sask., can cite many studies showing how specific nutrient deficiencies can increase specific diseases in specific crops. For example, “early examples showed that phosphorus deficiency leads to increased seedling rot due to pythium,” he says, citing a 1935 journal article by T.C. Vanterpool in the Canadian Journal of Research.

However, adding a nutrient to a crop that is not deficient will not “cure” a disease, he says. “For example it has often been suggested that copper will reduce ergot in wheat, but this is only true if the wheat is deficient in copper.”

If farms put the primary focus on higher nitrogen rates, that extra nitrogen — when other nutrients are out of balance — can actually rob yields. Is this true?

“I do not believe this for canola,” says Mario Tenuta, research chair in 4R Nutrient Stewardship at the University of Manitoba. He does believe it for other crops, giving two examples: wheat can lodge with excess nitrogen, and potatoes can have excess vine growth — two things that could, in theory, increase disease.

“I don’t believe this, except in the extreme, like where nitrogen levels become so high that they are toxic,” says Harding. “Studies I’m familiar with show that excess nitrogen is not advantageous or detrimental to yield. I do believe that excess nitrogen is a waste of money, so it will rob profit, but not yield. It is also possible that the lack of other nutrients may rob yield, but excess nitrogen will not.”

Others, including Cindy Grant, were believers. A retired research scientist with Agriculture and Agri-Food Canada at Brandon, Man., Grant says yield can decrease if growers add excess nitrogen without a balanced supply of other nutrients.

“Years ago, when I was a student and before it was widely recognized that our soils would be deficient in sulphur for canola, my husband-to-be had severe sulphur deficiency on his canola field,” Grant says. “It ended up getting every disease you could think of because the deficiency weakened it. I had one trial where every treatment that I used to improve nitrogen efficiency decreased canola yield because of an nitrogen:sulphur imbalance.”

Plants with correct nutrition have higher sugars (brix) and more secondary metabolites — compounds plants use to defend themselves. Is this true?

This one left most of our experts scratching, especially with regard to brix — a measure of plant sugars often used to assess grape sugar content when making wine. Higher brix means potentially higher alcohol content in the wine.

Cowell says brix is becoming a bit of a hot topic. “I have oddly been asked about brix many times this winter,” he says, “and my reply has been the same. If you grow wine and want to harvest for best sugar content, then brix is a tool to use. Otherwise, where is the data?”

Tenuta has a similar thought: “If brix was so useful, we’d be all be using it like a soil test.” He did, however, agree that good plant nutrition can lead to secondary metabolites useful in plant defence.

Xiaopeng Gao, associate professor of soil fertility and agronomy at the University of Manitoba, says “proper nutrient supply can improve plants’ photosynthesis efficiency, producing more sugars and secondary metabolites such as flavonoids, alkaloids and phenols. These compounds can help plants against attacks from pathogens and pests. Additionally, some compounds such as flavonoids can improve plants’ antioxidant properties, and therefore increase tolerance to abiotic stresses such as heat and drought.”

Soolanayakanahally agrees. “Higher secondary metabolites can impart better defence against pest and disease.”

There are 16 essential elements, each with a specific mode of action. We need to pay closer attention to micros. Is this true?

The experts generally agreed with this.

“I believe there is a growing need to pay attention to micros across Prairies,” Gao says. His reasons: one, canola, soybeans and corn have high requirements for micros and their acres, in total, are increasing. Two, fewer mixed farms mean lower use of livestock manure. And three, we are paying more attention to the importance of micros (for examples, iron and zinc) for human health.

Cowell says pay closer attention to micronutrients only if you need them. “The idea that micronutrient deficiencies are ‘hidden’ is a fallacy — these deficiencies tend to lead to yields falling off a cliff,” he says. He sees zinc applied to soils with no need for extra zinc and while he has seen boron deficiencies, it was “only on terrible soils that no one should farm.” Cowell’s conclusion: “Beyond that, this becomes a wasteland of marketing and improper sales.”

MORE ON MICROS: Soil fertility, revisited

Harding says manganese and zinc are “often heralded as having disease-reducing properties.” He also says boron availability is connected with clubroot infection in canola, and chloride deficiency can “predispose some crops to certain infections or physiological issues” — but again, only if they’re short.

Harding puts this whole conversation in perspective: while macronutrient and micronutrient fertility is a “critical agronomic principle necessary to allow the crop to reach its genetic potential, it is probably only occasionally a significant modulator of disease,” he says. “It is never as impactful as primary disease management principles like genetic resistance, crop rotation, clean seed and fungicides.”

The take-away

How do farmers use this information?

We interviewed a venture capital investor recently who encourages Canadian agriculture to at least pay attention to those voices at the fringe of common practice. Those may be the people who bring forth revolutionary ideas to make farming more efficient, more productive and more profitable.

In many cases, though, farms can advance all three of these by exploring the practices we already know.

Whether leaning into what we know or exploring the new and untested, it helps to have help. Get sound advice from an experienced agronomist. And listen to that little voice in your ahead that wonders, ‘Can this be right?’

“As we’ve gone down this road, the No. 1 skeptic has been my dad,” Matthews says.

What the family discovered together is that “the old days of strictly managing nitrogen, phosphorus and potassium are gone,” Matthews says. And from that point, their work with Cook has shown “plants in balance will have lower pest management costs.”

While we do not have much crop data to support this claim on the Prairies, the logic in those two broad statements is sound — as our experts have shown. How farmers achieve that “balance” is still open to debate. But if we are to make the efficiency gains we need to make, these are discoveries worth making.

The post FEED ME: Can well-fed plants fend off diseases and insects? appeared first on Grainews.

The two best defences are:

• Crop rotation with a break of at least two years between canola crops.
• Cultivars with effective resistance to the disease pathotypes in a field.

Seed treatment and early-season fungicides can also help, especially if the first two are compromised.

This article will explain blackleg disease and how it works, then provide management details to keep canola yield loss to a minimum.

What is blackleg?

Blackleg, also called phoma stem canker, causes necrosis of canola stems at ground level, restricting moisture and nutrient movement in the plant. In severe cases, the fungus can completely cut off this essential flow, killing the plant. In many cases, plants survive partial restriction but experience yield loss due to limited seed fill.

Two fungal pathogens cause blackleg — Leptosphaeria maculans and Leptosphaeria biglobosa. Both species are widespread throughout the Prairies. L. biglobosa is weakly virulent, and often associated with upper stem lesions. It rarely causes significant yield loss. L. maculans does more damage.

Canola plants are susceptible to blackleg infection at all growth stages. Infection at the seedling stage tends to cause more yield loss because the disease has time to develop through the growing season. That is why seed treatment and early-applied fungicide can help, especially if cultivars have limited genetic resistance. More on that later.

Blackleg pathogens overwinter on infected canola residue. In spring, fungus on old stem and root pieces produces fruiting bodies called pseudothecia and pycnidia. Pseudothecia release microscopic sexual spores, called ascospores, which become airborne and disperse to infect new canola plants. Ascospores are the primary agent of infection.

During the growing season, the pathogen also produces pycnidia, which appear as pepper-like spots within lesions on canola leaves and stems. Masses of tiny spores called pycnidiospores ooze from the pycnidia. These spores spread short distances by rain splash and wind, and cause secondary infection within a crop. Infected stubble can continue to produce ascospores and pycnidiospores for three to five years, although viability drops off considerably after two years. That is why crop rotation is an effective management practice. Again, more on that later.

From the original infection site, usually on leaves, the fungus grows down through the plant. As the season progresses, cankers form at the stem base. In severe cases, these cankers will completely fill the base of the stem, causing premature death.

The disease triangle

Diseases require a pathogen, a susceptible host and the right environment. Blackleg thrives in warm, humid conditions and with frequent rain showers.

Infection can occur in dry years, provided early-season showers produce the environment for spore germination, dispersal and infection. University of Manitoba research (Guo and Fernando, 2005) showed that pycnidiospore dispersal peaked during rainfall, and ascospore dispersal peaked several hours after rainfall of greater than two millimetres (or one-tenth of an inch). Ascospore dispersal persisted for approximately three days after such events. Wind increases pycnidiospore dispersal.

Yield loss

Agronomists can determine blackleg severity based on visual assessment of stem cross sections. With blackleg, discolouration often appears in a wedge pattern. If discolouration is more like a light-grey starburst pattern, it may be verticillium stripe.

The blackleg severity scale:

• 0 — No diseased tissue visible in the cross-section.
• 1 — Diseased tissue occupies up to 25 per cent of the cross-section.
• 2 — Diseased tissue occupies 26-50 per cent of the cross-section.
• 3 — Diseased tissue occupies 51-75 per cent of the cross-section.
• 4 — Diseased tissue occupies greater than 75 per cent of the cross-section with little or no constriction of affected tissues.
• 5 — Diseased tissue occupies 100 per cent of the cross-section with significant constriction of affected tissues; tissue dry and brittle; plant dead.

Research from Alberta (Hwang et al., 2016) found that each unit increase in disease severity reduced canola seed yield in the infected plant by 17.2 per cent. An updated yield loss model, also from Alberta researchers (Wang et al., 2020) showed the increase in yield loss as more quadratic than linear. Here is the conclusion, as written in the Wang et al. report from the Canadian Journal of Plant Science: “The results of the current study indicated that blackleg severity–yield loss relationships were explained by quadratic equations, in which slight L. maculans infection (disease severity of one) was associated with a small increase in yield relative to plants with no disease at all. When disease severity increased to ≥2, however, yields began to decrease dramatically.”

For these reasons, when disease levels approach a severity rating of two on a field (late in the season) Canola Council of Canada agronomy specialists recommend a change in blackleg management for that field in future years.

The Canola Council of Canada used these research results to build an online tool, the Blackleg Yield Loss Calculator, that calculates blackleg yield loss (and economic cost) based on field scouting results.

STEP 1: Scouting

Blackleg infection can occur at any time, and early infection tends to cause the greatest yield loss. Lesions may occur on cotyledons, leaves, stems and pods. These spots are dirty white, round to irregularly shaped, and usually dotted with numerous small, black pycnidia. Use a hand lens to help identify pycnidia specks. Under moist conditions, a viscous pink liquid carrying the pycnidiospores oozes from the pycnidia.

While very early-season scouting can indicate the need for a fungicide spray, canola growers and agronomists will use later-season scouting to assess disease severity, estimate yield loss and identify fields where increased future management is required.

Scouting at swathing or the week or two before straight combining requires cutting through the base of canola stems to assess stem canker. Look for dark necrotic discolouration in the interior of the stem base. This was described earlier, in the yield loss section.

To scout:

• Pull up 50 to 100 plants in a “W” pattern through the field, cutting 10 to 20 random stems at each of the five points in the “W.” Random selection is key to an accurate assessment. Do not seek out diseased stems. Start at a field edge, choosing the edge closest to a previous canola field.
• Clip at the base of the stem/top of the root and look for blackened tissue inside the crown of the stem. Start around one inch below ground level and take various cuts up through the stem base. The amount of infection present will help identify the level of risk and the best management practices for that field in the following years.
• Use the zero to five blackleg disease rating system to identify severity. Also, tabulate what percentage of the sampled plants have a blackleg infection. This is the “incidence” of disease.

Then, enter results in the blackleg yield loss calculator.

STEP 2: Test for blackleg races

If blackleg seems to be getting worse, agronomists and growers can test stubble to identify the dominant blackleg races present in a field. The population of blackleg races can shift in a field, and cultivars are not resistant to all races.

Canola activates a resistant response to blackleg when the plant “recognizes” the corresponding L. maculans avirulence genes (Avr) in the pathogen. This is called gene-for-gene (also called qualitative or major gene or race-specific) resistance. If a pathogen has an Avr gene that matches the plant’s resistance “R” gene, the R gene recognizes the pathogen and causes the plant to initiate a defence or immune system response. Resistance only results if both the Avr gene in the pathogen and the corresponding R gene in the host are present.

If the plant does not have an R gene that matches the pathogen’s Avr gene, the plant does not put up an immune response, and blackleg infection can occur. Stubble tests can identify the common Avr genes in blackleg-infected stubble, and growers can then choose canola cultivars with R genes that correspond with those Avr genes.

Various labs will test stem pieces for blackleg and can provide analysis of blackleg races present.

The first step is to gather samples. Collect fresh stem pieces around the time of swathing or in the weeks before straight combining. Cut just below the crown of the plant into the root material, to look for black discolouration in the cross-section. Collect 10 to 12 infected stems from each field, providing 10-inch (25-cm) stem lengths starting from around one inch below ground level. Some labs will use smaller pieces. Check with each lab for their protocols. See sidebar for labs.

Labs can also test old canola stem pieces collected from fields that will be in canola next year.

Next is the lab analysis. Labs determine the blackleg species present — L. biglobosa or L. maculans — and run DNA tests to determine the races.

Then it’s time to interpret the results. Lab results show the predominant race of blackleg or give a frequency breakdown of blackleg races found within the samples provided. Results also list the Avr genes found in each race. As noted earlier, major R genes in canola cultivars need to match up to Avr genes in the pathogen to be effective.

Lab results may look something like this:

• Race 1 — AvrLm2-Lm4-Lm5-Lm6-Lm7-Lm11 (25 per cent)
• Race 2 — AvrLm4-Lm5-Lm6-Lm7-Lm11 (50 per cent)
• Race 3 — AvrLm1-Lm4-Lm5-Lm6-Lm7 (25 per cent)

Growers will want to select a canola cultivar with a major gene that corresponds with an Avr gene found in all three races. Avirulence gene 4 (AvrLm4) is one example of a gene found in all three common blackleg races in that field. Using a cultivar deploying a major gene of Rlm4 (or Group E1) would be a suitable match. The next section describes this in more detail.

WATCH MORE: This video explains how to use a Leptosphaeria maculans race test to choose the right blackleg resistance for your canola field.

STEP 3: Choose resistant cultivars

Agronomists and canola growers can use results from step two to choose a cultivar with qualitative resistance to the predominant blackleg races in a field.

Cultivars often also have some degree of quantitative resistance (also referred to as minor gene or adult plant resistance), believed to come through the function of many genes each with a relatively small effect. Canola cultivars express quantitative resistance at the adult plant stage. The result is reduced development of necrotic tissue at the stem base compared to that found in susceptible cultivars. Canola breeders likely use both quantitative and qualitative resistance to develop blackleg-resistant canola cultivars.

Qualitative resistance, described earlier as gene-for-gene resistance, is a major-gene trait. Serious infection is more likely when the dominant blackleg race in a field does not match the cultivar’s qualitative R gene.

Using the same resistance genes repeatedly in the field over time can select for blackleg races virulent against that resistance.

The mix of blackleg races will be different in every field, and the mix changes over time. That is how a cultivar that earns an “R” rating at the time of registration may not actually perform like an R cultivar in every field.

The Western Canada Canola/Rapeseed Recommending Committee has established blackleg testing protocols and ratings to assess resistance. The resistance ratings currently available for commercial cultivars indicate disease incidence and severity relative to check cultivars in disease testing sites.

The committee uses the following to describe the level of resistance compared to the highly susceptible cultivar Westar:

• R (Resistant) = up to 30 per cent of the severity of Westar
• MR (Moderately Resistant) = 30-49 per cent of the severity of Westar
• MS (Moderately Susceptible) = 50-69 per cent of the severity of Westar
• S (Susceptible) = 70-100 per cent of the severity of Westar

Blackleg R-gene labels are voluntary for seed companies. Not all companies participate. Seed companies that participate in the blackleg R-gene labelling program use the following letter system to identify major resistance genes present in each resistance group (RG):

• RG A = Rlm1 or LepR3
• RG B = Rlm2
• RG C = Rlm3
• RG D = LepR1
• RG E1 = Rlm4
• RG E2= Rlm7
• RG F = Rlm9
• RG G = RlmS or LepR2
• RG X = unknown

Here are three example blackleg labels you could find on a bag of canola seed:

R (BC): The traditional R rating means the average field performance of blackleg resistance was below 30 per cent of Westar, the susceptible check. The additional “(BC)” designation means the cultivar contains the resistance genes Rlm2 and Rlm3.

MR (A): The traditional MR rating means the average field performance of blackleg resistance was 30-49.9 per cent of Westar check. The additional “(A)” means it contains the resistance gene LepR3 or Rlm1.

R (CX): As an R-rated cultivar, the average field performance of blackleg resistance was below 30 per cent of Westar check. (CX) means it contains the resistance gene Rlm3 and an unidentified major resistance gene.

The Canola Encyclopedia has a table of current canola cultivars and their traits. It identifies the blackleg R gene label for participating cultivars.

Genetic resistance is a key part of blackleg risk management. When growers use other management practices — especially longer breaks between canola crops and R-gene rotation — they protect genetic resistance and minimize the effect of these new strains.

STEP 4: Extend the break

Crop rotation allows for infected canola residue to decompose, reducing the spores available to infect the next canola crop.

A break of two or more years between canola crops on the same field will give most blackleg resting spores time to degrade, greatly reducing the risk. In tight rotations, scouting is essential and it becomes more important to use cultivars with genetic resistance to the most common blackleg races in a field.

Years ago Randy Kutcher, at the time a research scientist with Agriculture and Agri-Food Canada in Saskatchewan, led a rotation study to test the necessity of the recommended one-in-four rotation when growing blackleg-resistant cultivars. The four-year rotation was a key management step in the years before resistant cultivars. Kutcher published the results in the article, published in the Canadian Journal of Plant Pathology in 2013. Access it online here.

Kutcher and his co-investigators compared the following rotations:

• continuous canola (C)
• continuous pea (P)
• wheat-pea (W-P)
• wheat-canola (W-C)
• wheat-pea-canola (W-P-C)
• wheat-pea-wheat-canola (W-P-W-C)
• wheat-flax-wheat-canola (W-F-W-C)

Location one was on dark brown soil at Scott, Sask., from 1998 to 2007. Location two was on black silty clay soil at Melfort, Sask., from 1999 to 2006. Kutcher and his colleagues ran four replicates of the seven rotations with all phases of each rotation present every year. They also repeated every phase with two different canola cultivars — a blackleg-resistant hybrid typical of the most advanced cultivars available at the time, and a blackleg-susceptible open-pollinated (OP) cultivar “typical of those in use when the four-year rotation recommendation for canola was developed,” the journal article reported.

Here is an excerpt from the article abstract:

“The results suggest that canola cultivars with strong blackleg resistance can be grown more intensively than once every four years with limited yield reduction. However, the increased severity of infection and amount of infested residue produced as canola rotations are intensified, which occurs even with resistant cultivars, increases the risk of inoculum carryover, resistance breakdown and yield loss. Therefore, it would be prudent for western Canadian canola growers to adhere to less intensive inclusion of canola in rotations, such as one canola crop in four years, as an effective blackleg management strategy.”

While tighter rotations can maintain low blackleg levels, scouting is essential. Blackleg severity scores of two or more in an R-rated hybrid is a sign of race shift. On that field, canola may need a three-year break between canola crops and a shift to hybrids proven to have different blackleg R genes.

STEP 5: Use enhanced seed treatment

Gary Peng, a research scientist with Agriculture and Agri-Food Canada in Saskatoon, recently completed studies on early blackleg infection and seed treatment. Peng showed that early blackleg infection at the cotyledon stage leads to higher disease incidence and severity at canola maturity.

The Canola Research Hub has a summary of the study, called Exploring novel seed treatment options to mitigate the impact of blackleg on canola. The summary says L. maculans inoculum of over 10,000 spores per gram of soil can result in severe blackleg via root infection, especially if roots are wounded (by root maggots, for example). Of the seed treatments Peng tvested, fluopyram, Saltro (active ingredient pydiflumetofen) and Bion (acibenzolar-s-methyl) showed promise to protect susceptible cultivars against the early blackleg infection, either through roots or from cotyledon and leaf wounds. Saltro is currently available for canola in Canada. Another option, not tested in this project, is Lumiscend with the active ingredient inpyrfluxam.

Peng also co-investigated another study, along with Dilantha Fernando and Shuanglong Huang from the University of Manitoba, looking at fungicide seed treatment to protect those cotyledons. When researchers applied L. maculans ascospores and pycnidiospores directly into canola plants through fresh wounds, fluopyram seed treatment reduced blackleg relative to non-treated control. The treatment did not show a benefit on resistant cultivars. Researchers showed that seed treatment could protect canola plants from blackleg spores that enter early through wounds on cotyledons. Insect feeding and hail can cause these wounds.

Again, the critical note here is this: Is the chosen canola cultivar actually resistant to the blackleg races in a field? If resistance is compromised, seed treatment known to be effective on blackleg may be a good tool to protect against critical early-season blackleg infection.

STEP 6: Apply foliar fungicide

Early-season fungicide can benefit partially resistant or susceptible cultivars, especially if environmental conditions are moist enough to support early infection. Use Group 11 products with high water volume for coverage, and ideally apply before infection.

Gary Peng, continuing his blackleg fungicide work, also looked into foliar application on very small canola plants. In his paper, Early fungicide treatment reduces blackleg on canola but yield benefit is realized only on susceptible cultivars under high disease pressure, published in 2021 in the Canadian Journal of Plant Pathology, Peng concluded that Group 11 fungicide applied to a blackleg-susceptible cultivar at the two- to four-leaf stage could reduce disease severity enough to provide benefit. Read the paper online here.

Early-season fungicide to prevent blackleg can provide a return on investment in a field with all of the following:

• Canola is in a tight rotation.
• The canola seed lot does not have enhanced seed treatment.
• Blackleg was present in the previous canola crop and infected stubble is found in the same field or in a neighbouring field. If the field was not scouted but the area has a history of blackleg, you could assume blackleg is present. This covers the pathogen part of the disease triangle.
• The cultivar is susceptible to blackleg races in the field. Wounds from hail or insect feeding can increase the risk of infection. This covers the host part of the disease triangle.
• Moist weather with wind, mist and rain splash (early in the season, during the critical infection window) can increase the spread of blackleg spores from stubble to living tissue. Fungal growth also tends to be more active in moist conditions. This covers the environment part of the disease triangle. 

Fungicides can go in a tank mix with herbicides — both of which tend to provide greater economic benefit when applied early. Fungicides for blackleg have protectant activity and little or no eradicant activity, so growers will want to apply them before blackleg symptoms appear. Consult the label or a current guide to crop protection for application details on all fungicides registered for blackleg.

Noteworthy extras

Verticillium stripe and blackleg. Researchers have shown a connection between blackleg and verticillium stripe infection. Often both diseases are found together in a plant. One way to reduce verticillium risk may be with a strong blackleg-resistant cultivar, but this hypothesis has not yet been tested.

Weeds as blackleg hosts. Canola volunteers and related weed species stinkweed, shepherd’s purse, wild mustard and flixweed are all blackleg hosts. If not controlled, these volunteers and weeds act as a disease bridge, reducing the effectiveness of rotation and cultivar resistance for disease management.

Tillage and burning to manage blackleg. Randy Kutcher, while with AAFC at Melfort, looked at tillage and burning to manage crop diseases. He published in the journal in 2010. He wrote the paper based on Saskatchewan field studies from 2000 to 2004, which included some very dry years. The paper has this statement: “Leaf spot severity of barley was usually slightly reduced under conventional tillage (CT) compared with zero tillage (ZT), but regardless of severity, barley yields were either similar or more often higher under ZT than CT. There were occasional effects of burning on barley yield, but results were inconsistent and sometimes depended on the tillage system. Canola yield tended to be greater under ZT than CT, but the effect of burning was inconsistent.… We conclude that use of fire to manage diseases of barley and canola is ineffective.”

ALSO: Labs that test canola stubble for blackleg races

Check sampling protocols for each lab.

Manitoba’s Pest Surveillance Initiative (PSI) Lab

Winnipeg, Manitoba

Discovery Seed Labs

Saskatoon, Saskatchewan

20/20 Seed Labs

Nisku, Alberta

Winnipeg, Manitoba

SGS Canada Labs

Sherwood Park, Alberta

Grande Prairie, Alberta

To take the CEU quiz for this article, CLICK HERE.

The post Steps to stop blackleg in canola appeared first on Grainews.

Soil acidity below a pH of 5.5 will reduce yield for common crops on the Prairies. Yield loss can be significant in soils below pH 5. Lime can be expensive, but may pencil out as the most important fertilizer treatment for soils with strong acidity.

Taylor Wallace has acidic soils — including one field with pH below 5. That has to affect yield, he thought. So in the spring of 2023, the farmer from Unity, Sask. gave that field 500 lbs. per acre of lime.

A shot of lime reduces acidity. Soil pH below 6 to 6.5 starts to hamper phosphorus availability, and this problem gets steadily worse as pH drops. By around pH 5, acidity has also released enough aluminum and manganese ions to poison root growth and function.

Wallace paid $530 per tonne for pelletized lime. His 500-lb. (227-kg) rate cost him around $120/acre. He based the rate on the experience of a neighbouring farmer, who ran a trial comparing 300, 400 and 500 lbs./ac. The higher rate provided the best results.

“I haven’t seen any results yet,” Wallace says. “Although we did have two fairly dry years in 2023 and 2024.”

READ MORE: Liming and soil acidity

Products to increase soil pH include calcitic lime, which is calcium carbonate; dolomitic lime, which also has magnesium; spent lime from water treatment plants and sugar beet processors; and wood ash.

Lime needs moisture to become active, and uniform distribution is key. Lime also requires high rates. One tonne per acre would be considered a low rate to treat soil with pH below 5. Wallace applied one quarter of that rate.

Norm Dueck is a consultant for A&L Labs in the Peace River region of Alberta — a region with millions of acres of strong acid soils. He has a lot of conversations about lime. Liming is common practice in acidic soils around the world, and the research is sound, he says. “We don’t need to reinvent the wheel. We know lime will do what it is scientifically proven to do.”

An early 1990s study at Agriculture and Agri-Food Canada’s Beaverlodge research centre in northern Alberta looked at lime effects on canola yield and brown girdling root rot. The study site had a soil pH of 5.13 in the top four inches. Researchers applied 7.5 tonnes per hectare (three tonnes per acre) of agricultural grade calcitic lime — primarily calcium carbonate — in May 1991, and tilled it in to a depth of four inches. This increased pH to 6.6 in year one. Canola grain yield increased 37 per cent in tilled soil and 17 per cent in no-till soil. Brown girdling root rot severity went down.

A 1970s Peace Region study, led by Alberta researcher Doug Penney, compared lime benefits for canola, barley, alfalfa and red clover. Researchers limed to a target pH of 6.7. The study concluded that at pH below 5, all crops will likely have severe yield loss without liming. For soils with an original pH of 5 to 5.5, the lime application increased alfalfa yield 80 to 100 per cent, barley 10 to 15 per cent, and canola and red clover five to 10 per cent.

Despite these results, liming has not taken off in the region. “Sometimes I feel like I’m banging my head against the wall,” Dueck says.

Cost is a big hurdle. Lime cost can vary widely depending on product, location and rate. Transportation is a big component. Soil with pH below 5 will need a minimum of two to four tonnes per acre. On top of that, the benefit has a limited lifespan. Lime can be over $100/acre per year, when averaged over time.

However, if acidity affects yield, lime can be the field’s most essential fertilizer.

“In the end, there are no shortcuts or substitutes for raising soil pH,” says John Breker, a soil scientist with Agvise Laboratories in North Dakota. “Elsewhere in the world, people have battled soil acidification for centuries, and the answer always comes back to liming.”

Breker has Idaho research showing how quickly yields fall once pH hits a certain threshold. In that study, wheat and barley yields in soil with pH 5 were only 60 to 80 per cent of yields in soils with pH of 5.3. The effect started sooner and cut deeper for pea and lentil — yield drop started at pH 5.8 and was down to 50 per cent at pH 5.

Where to start?

“The most overlooked factor is the variability of pH within fields,” Dueck says. He has seen many fields that range from below pH 5.0 to 6.5. “You might need two tonnes per acre, or more, on the low pH areas and nothing on the 6.5.”

For a test, farms could start with the most acidic part of their most acidic field. That’s what Wallace did. Soil pH probes can quickly identify areas with the lowest pH. With the target area identified, send one composite soil sample to a lab to set the rate.

Lime rate depends on soil buffer pH, a factor of the soil’s cation exchange capacity. Soils with low pH and low buffer pH require a lot more lime. Labs will test soil for pH and buffer pH, and also test lime sources for “calcium carbonate equivalent.” With these tests, labs can provide lime rate guidelines based on lime quality and the farm’s target pH.

Penney, who conducted the lime study in the Peace Region in 1970, is a lime expert. He said lime has “no mobility” in the soil, so it needs uniform distribution. Best results come from powder form applied generally throughout the soil. Penney recommends surface application over dry soil, then heavy harrow to mix dry soil with dry lime, then cultivation to mix it into the top three or four inches.

Alternative treatments

Lime is the only real way to increase soil pH. One alternative is to simply live with lower productivity on strong acid soils.

Another alternative is higher rates of phosphorus. This will overcome some of the phosphorus no longer plant-available because of bonds with aluminum and iron.

Some wheat cultivars are more tolerant to low pH. Farmers could ask seed companies if they have data for Canada. Farmers could also look at entirely new crops. Blueberries tolerate strong acid soils. Nova Scotia has strong acidic soils and wild blueberry is the No. 1 export crop in the province. Potatoes, wild rice and commercial grass sod also tolerate acid soils.

Wallace said crop and cultivar decisions may improve results in low-pH soil, and adjusted phosphorus rates may help. But he still saw the need for lime.

“As land becomes more expensive, it becomes more important to get the most out of the land you have,” Wallace says. “Proper soil testing and a variable rate application probably provide the best path to value from lime.”

The post It may be time for lime on acid soils appeared first on Grainews.

The disease, caused by the Verticillium longisporum pathogen, was first reported in Manitoba in 2014. In 2015, Canadian Food Inspection Agency surveyors found the pathogen in six provinces, including all three Prairie provinces.

The 2021 Manitoba disease survey marked the first year that surveyors had the protocols to accurately identify verticillium stripe. (More on accurate identification later.) In that year, 30 per cent of Manitoba fields had the disease. This is “prevalence.” And, on average, 15 per cent of plants in those fields had obvious symptoms. This is “incidence.”

A year later, Manitoba prevalence rose to 38 per cent and incidence to 23 per cent. These numbers come from the Western Forum on Pest Management oilseed diseases report, based on 116 Manitoba fields surveyed. A 2022 survey, targeted at eastern Saskatchewan areas deemed more likely to have the disease, found symptoms in many fields. Alberta numbers in 2022 were very low.

Verticillium stripe levels were lower in Manitoba in 2023, with prevalence of 29 per cent and incidence of 11 per cent. The forum’s 2023 report notes that the Saskatchewan Ministry of Agriculture ran a verticillium-specific survey targeting 100 fields.

“Preliminary observations seem to suggest that verticillium stripe is no longer a rare disease in Saskatchewan,” the report reads. Alberta surveyors suspected verticillium stripe in three per cent of fields surveyed.

David Kaminski, Manitoba Agriculture field crop pathologist, in talking to reporter Richard Kamchen for a Canola Digest article in 2023, says he’s not sure why Manitoba levels are higher than the rest of the Prairies.

“Clubroot originated in Alberta and made its way east, and some people say blackleg originated in Saskatchewan and made its way east and west, and in that kind of analogy, we could say that verticillium has been more prevalent in Manitoba and seems to be moving westward,” Kaminski says. “But we don’t have full documentation on that.”

The bottom line is that the disease is likely here to stay. Agronomists need to know how to recognize it and make science-driven recommendations for management.

What is verticillium stripe?

The fungal species Verticillium longisporum causes verticillium stripe, a plant disease that leads to stem striping, blockage of the xylem and stunted seed fill in canola.

The Canola Encyclopedia chapter on verticillium stripe cites a study by Inderbitzin et al, printed in PLoS ONE in 2011, showing that V. longisporum is a diploid hybrid of three species, including V. dahliae.

V. dahliae is present in Canada as a pathogen of potato, tomato, sunflower, strawberry, cabbage and maple. Based upon genetic analysis, the researchers showed that V. longisporum originated independently at three different times, involving four different lineages and three different parental species.

Each V. longisporum lineage was genetically homogenous and contained one set of alleles that were identical across lineages. This has a potential effect on screening for resistance genes in Brassica napus and other related species and implications for disease management.

A more recent Canadian study, Verticillium disease etiology and nursery, with principal investigator Dilantha Fernando from the University of Manitoba, looked into the genetic diversity and behaviour of V. longisporum in Western Canada.

Fernando, writing in his final report, noted that “molecular DNA studies of V. longisporum indicated that the pathogen is a diploid hybrid of V. dahliae and two unknown species forming three lineages A1/D1, A1/D2 and A1/D3. V. longisporum lineage A1/D1 is considered the most virulent group across Brassicaceae crops, especially canola, followed by A1/D3 and A1/D2.”

Fernando and his team tested infected canola samples from different locations in Manitoba, Ontario and Saskatchewan. All 14 samples from Manitoba were confirmed as A1/D1, the most virulent group. All three samples from Ontario were confirmed as V. dahliae. And out of six samples collected from Saskatchewan, one each was confirmed as A1/D1, A1/D2 and A1/D3, and the other three were V. dahliae.

Disease cycle

The soil-borne fungus infects roots and travels up the water-transporting xylem in the stem. It will eventually plug the xylem, cutting off the flow of nutrients.

The Canola Encyclopedia provides a detailed description of the verticillium stripe disease cycle and is the source for content in this section of the article. Verticillium stripe is a monocyclic disease, meaning it only goes through one cycle each year. While it is hard to pinpoint a start point in a cycle, the encyclopedia starts with rapid germination of fungal propagules from microsclerotia in the soil. Host plant root exudates trigger this germination, and these propagules infect the canola roots at their most susceptible location — the fast-growing root tip.

The plant is most susceptible to V. longisporum infection when canola starts flowering, according to Zhou et. al. in a report published in Plant Pathology journal in 2006. Zhou found that the fungal hyphae entered the root vascular system through an opening, often a wound. After the hyphae multiply in the root, hyphae and single-cell spores called conidia are produced locally in the xylem and moved through the vascular system of the plant to multiply.

This prevents the regular flow and functionality of water and nutrients to the plant tissues and eventually causes the xylem to plug, turn black, collapse and shrivel, as described in Eastburn and Paul’s verticillium chapter in the 2007 Compendium of Brassica Diseases.

As the plant begins to mature and senesce, the pathogen moves from the xylem into the surrounding non-vascular tissues, where multi-cellular microsclerotia are formed in the dying tissue, as Zhou describes. Likewise, conidia production in the stem base and roots causes the tissues to turn dark grey, then black and can cause the lateral roots to eventually break down, making it easy to pull from the ground.

While the plant begins to show progressively more intense symptoms of the disease, the microsclerotia in the stems cause the stem epidermis (thin outer layer) to peel back. At this point the stem may take on a shredded appearance and the microsclerotia will be released to the soil, where they will rest until stimulated to germinate again. The microsclerotia remain viable in the soil for several years, especially if infected residue is incorporated into the soil after harvest.

Environmental influence

Verticillium stripe tends to be more damaging in hot, dry conditions. These stressful conditions, the Canola Encyclopedia notes, tend to reduce root and xylem function, while excess moisture makes the disease less of an issue. Plants with damaged roots also make it easier for the disease to enter the vascular system, note Heale and Karapapa in the Canadian Journal of Plant Pathology, 1999.

Verticillium stripe can use weedy host species such as wild mustard and others outside the Brassicaceae family as host species. The Canola Encyclopedia again cites Eastburn and Paul, who report that V. longisporum can affect several annual and perennial plant species in both temperate and subtropical zones.

The pathogen is also present in oilseed rape in Sweden, Germany, Poland, Ukraine, Russia, France, Czechia, Belgium, the Netherlands, the U.K. and Japan, and can infect many crops including broccoli, cabbage, cauliflower, horseradish, radish and wild mustard.

Symptoms

Infection can occur in a few scattered plants, in small areas or across the whole field. Symptoms are not typically noticed until plants are near maturity.

The Canola Encyclopedia provides a detailed description of symptoms:

• Verticillium stripe’s restriction of water and nutrient uptake leads to stunting and premature senescence.
• Faint black striping on the stems can appear darker and more obvious when rubbed.
• By peeling back the epidermis and outer cortex of the stem, observers can find blackening on the inside of the stem and microsclerotia later in the growing season.
• Striping can be more obvious closer to harvest.
• At the end of ripening, microsclerotia can germinate and produce conidia spores, giving the stems a powdery look.

I also wrote a 2022 Country Guide article with a few more details. Early infection can show up as grey or tan diseased stripes up one half of the stem — hence the “stripe” name. As verticillium infection progresses, the epidermis will peel away from weakened stems to reveal tiny specks called microsclerotia underneath. Eventually, verticillium infection blocks the transfer of water and nutrients, weakening the stem and killing the plant.

Canola Council of Canada staff note in the Country Guide article that, “because we’re letting canola stand longer, either for straight combining or later swathing, we may be noticing the disease more than we used to.”

Country Guide also included observations from Manitoba farmer Brad Crammond. In 2020, he had stems breaking off and toppling, making it look from a distance like a case of severe lodging.

“We had some big winds in August that year and a lot of talk on Twitter was about crops going down and making harvest difficult,” he says. “In retrospect, the cause for many of these cases may have been verticillium stripe.”

Symptoms may be hard to notice in less severe cases, especially since mild cases will look like regular senescence. The encyclopedia adds that hail or physical damage can also cause lesions similar to verticillium stripe, but these lesions will not have microsclerotia beneath the epidermis.

Because symptoms continue to develop right up to harvest, the late season is a good time to scout for verticillium stripe. That is when scouters are most likely to see the bleached and brittle stems, the peeling epidermis and the microsclerotia underneath that peeled skin. At that time, stem cross sections will also show a starburst-like pattern as conidia build up.

The bigger challenge, perhaps, is to distinguish verticillium stripe from other common diseases, especially blackleg and sclerotinia stem rot.

Other diseases

This section describes how to distinguish verticillium stripe from other common canola diseases. Below are the four major symptoms of verticillium stripe, each with similarities to symptoms of blackleg or sclerotinia stem rot.

Stem striping. When the crop is full height but still green, canola plants infected with verticillium stripe will often have a two-toned stem — half healthy and green and half discoloured and drying down. This half-stem senescing is where the “stripe” name comes from.

You will not see half-stem senescing with blackleg or sclerotinia stem rot. Sclerotinia will cause stem discolouration, but it will not stripe half the stem. The only other disease to cause similar symptoms is fusarium wilt, but current canola cultivars all have resistance to that pathogen.

Stem cross-section discolouration. Verticillium stripe infects roots and enters the plant’s vascular system. Verticillium hyphae and conidia fill up the vascular system, restricting the passage of water and nutrients throughout the plant. This gives the stem cross-section a greyish colour that is easily confused with blackleg.

There are two tips to distinguish the pathogens:

• With blackleg, stem tissue infection tends to be darker and causes distinct black wedge shapes. Verticillium is a lighter grey, more general throughout the cross-section and can present in more of a starburst pattern.
• Blackleg stem discolouration is confined to the crown area at the base of the stem. Verticillium darkening can extend well up the stem.

“Verticillium will present some general discolouration, generally in a starburst-like pattern. Blackleg will present itself in a distinct solid black wedge covering a percentage of the stem,” says Canola Council of Canada agronomy specialist Courtney Ross.

Stem peeling and weakening. Peeling stem skin is a symptom of verticillium stripe. Under that peeled outer layer will be the microsclerotia, often taking the shape of faint black vertical striping. Severely diseased stems may break off and can be confused with lodging. Sclerotinia stem rot will also cause weakened, brittle stems, but sclerotinia will not have the stripy, speckly microsclerotia. Sclerotinia stem rot will cause the entire stem tissue to shred, not just the outer layer.

“The shredding of the stem symptom is comparable to sclerotinia. However, the hollowing of the stem and larger sclerotia bodies from sclerotinia are different from the smaller microsclerotia present from verticillium stripe,” Ross says.

Black specks. As verticillium infection advances, microsclerotia will form on the underside of peeling stem skin. These can be found all the way up the stem. Verticillium specks may seem similar to blackleg pycnidia, but they’re much smaller — more like powdery pepper. In some cases, blackleg pycnidia will have a purple-pinkish ooze of pycnidiospores around them.

Blackleg pycnidia are also confined to a lesion no more than a couple of centimetres in size. If you see pink and specks confined to a lesion, it’s blackleg.

Yield loss

If infected plants ripen prematurely, they can show significant yield reduction.

Verticillium longisporum could cause significant yield damage in canola, but only when disease severity and infection are high, states the Canola Encyclopedia, citing Heale and Karapapa. As disease onset is late in the growing season, verticillium stripe is less damaging than other diseases such as blackleg or sclerotinia stem rot.

However, Dunker et al, in a 2008 article in the Journal of Phytopathology, reported on European research showing significant rapeseed yield loss when infection establishes early. They report yield loss in this situation at 10 to 50 per cent. A big factor in yield loss is smaller seed size.

In 2016, Jasper Depotter, a plant pathology researcher at the University of Cologne, published results from field trials in the United Kingdom. His study showed yield loss as high as 34 per cent, with differences among cultivars.

“In a bad year on a susceptible cultivar, the estimates of Dunker seem realistic,” Depotter was quoted as saying in the Country Guide article.

There is no rating scale for the severity of verticillium stripe, and thus no way to quantify yield loss. Ross notes that research is underway to uncover yield implications in Western Canada.

In Country Guide, Crammond says he noticed, on Aug. 10, 2020, some sudden and premature die-off in a seemingly healthy field of canola.

“We’ve had issues with blackleg in the past and I could tell this was something different,” said the farmer from Austin, Man.

So, he called his Canola Council of Canada agronomy specialist to take a look. Samples sent to Manitoba’s PSI Lab confirmed the diagnosis: advanced verticillium stripe.

Unlike other diseases, it can be more severe in dry conditions, which could explain why the disease reached new heights in 2021.

Management

Scouting. Accurate identification will be easier with experience. Verticillium stripe is easiest to scout just before or just after harvest when symptoms are most obvious. Accurate identification is an important step in disease management.

Blackleg and sclerotinia stem rot, if those are present, are more manageable through genetic resistance, crop rotation and fungicides. Verticillium stripe has few proven management steps.

Test plant tissue. If scouters find symptoms that look like verticillium stripe, they could use lab tests for confirmation. Labs in Canada that provide this service include:

• 20/20 Seed Labs, 507-11th Ave., Nisku, AB T9E 7N5. Phone: 780-955-3435. Web:
• Discovery Seed Labs, 450 Melville St., Saskatoon, SK S7J 4M2. Phone: 306-249-4484.
• Pest Surveillance Initiative (PSI), 5A-1325 Markham Rd., Winnipeg, MB R3T 4J6. Phone: 204-813-2171.

Contact labs for their sampling protocols.

Reduce soil movement. Verticillium microsclerotia are soil-borne, so steps to keep soil in place could reduce spread somewhat. The outlines a few biosecurity measures. As V. longisporum is a soil-borne pathogen, biosecurity practices can help mitigate the spread of this disease, on- and off-farm. These include equipment and tool sanitation, controlling off-farm traffic, monitoring seed, feed and fertilizer sources, and developing an on-farm biosecurity plan.

Extend the break between canola crops. Two- or three-year breaks between canola crops are good disease management in general. However, verticillium microsclerotia can persist 10 to 15 years in the soil, as Agriculture and Agri-Food Canada research scientist Hossein Borhan notes in a Canola Research Hub report.

Despite that persistence, Crammond’s on-farm experience, as described in Country Guide, shows that rotation could work. One of his canola fields in 2020 was on a half section with a mixed cropping history. Eighty acres in the middle had quinoa, soybeans and wheat over the previous five years and no canola.

The rest had been in a wheat-canola rotation for “quite some time,” he says. While the rest of the field turned brown prematurely due to verticillium stripe, the 80 acres with a longer break between canola crops stayed green and healthy. It was all the same cultivar.

The Canola Encyclopedia notes that in northern Europe, where this disease has been an important issue for more than 30 years, researchers recommend that growers leave three years between canola crops. This allows pathogen populations in the soil to naturally decline.

But, due to the long-lived microsclerotia, rotation alone is not enough to manage this problem effectively.

Ask about genetic resistance. Seed companies, if asked, might be able to shed some light on differences. Crammond’s on-farm experience shows differences between cultivars do exist. In 2021, he ran out of seed in one field and finished the final eight acres with a different cultivar. While most of the field was at risk of shelling out due to high levels of verticillium stripe, the eight acres of a different variety had no issues, he says.

Dilantha Fernando, a professor in the department of plant science at the University of Manitoba, tested germplasm from international sources and dozens of lines supplied by Canadian seed companies. He says some have superior levels of resistance, but lines supplied to him were not identified so he doesn’t know if any were commercial cultivars.

Hossein Borhan leads a new study that will provide an understanding of genetic resistance to verticillium stripe. He and other researchers on the project identified two locations within B. napus DNA that seem to convey resistance to V. longisporum. Borhan also screened 50 B. napus lines within the AAFC nested association mapping program to compare their verticillium stripe resistance. Some lines are very resistant and some are very susceptible, he says.

Papers from Eynck et. al., in the Journal of Plant Diseases and Protection, 2009, as well as Heale and Karapapa, show that other Brassica species, namely B. carinata and B. oleraceae, have low susceptibility to verticillium and show almost no resulting yield loss. This adds further evidence to the potential for breeding solutions to manage this disease.

No treatments. No fungicide or soil amendment is known to be effective on verticillium stripe. As part of Borhan’s study, researchers found a microorganism that could potentially protect against V. longisporum. If proven to work and if it can be effectively mass-produced and applied to the soil or roots, it could provide growers with a biological control product.

Manage blackleg. Alberta research shows an interaction between blackleg and verticillium stripe pathogens. So, while growers have limited tools to manage verticillium stripe at this time, steps to manage blackleg could ultimately reduce yield loss from verticillium stripe.

University of Alberta researchers Yixiao Wang, Stephen Strelkov and Sheau-Fang Hwang, in an article published in the journal Plants in 2023, report on their assessment of L. maculans/V. longisporum interactions under field and greenhouse conditions.

Their conclusion, as written in the article: “When L. maculans was co-inoculated with V. longisporum, blackleg severity and yield losses increased. In some cases, verticillium stripe caused greater yield losses than blackleg. The results suggest that the interaction between L. maculans/V. longisporum may cause more severe losses in canola, highlighting the need for proactive disease management strategies.”

While many treatments could potentially work, all we know for certain is that there seems to be a connection to blackleg. Verticillium stripe has few proven management steps.

For now, look for the disease. If identified and if it’s causing yield loss, consider, at a minimum, the time-honoured disease management strategy — longer breaks between canola crops.

To take the CEU quiz for this article, click here.

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Weather conditions often conspire against these best laid plans, pushing canola growers to plan B: foliar insecticide.

Farmers get particularly frustrated when plan B requires multiple sprays. Here are a few steps to improve insecticide results and hopefully cut down on the number of sprays required.

1. Set a realistic threshold

In high-risk areas where a crop is stalled and flea beetles are feeding aggressively, the action threshold of 25 per cent may be met and surpassed within hours. Experienced canola growers are fairly good at spotting scenarios where a field is going sideways quickly.

“In this situation, growers may want to spray at less than 25 per cent leaf area loss, and give the crop a chance to get through the day a little stronger,” says Curtis Rempel, Canola Council of Canada vice-president of crop production and innovation. Note that some feeding is required for flea beetles to take up the systematic seed treatment, so spraying after the first nibbles may mean wasting any potential benefit from the seed treatment.

2. Target field edges

Flea beetles in Western Canada winter as adults in sheltered areas, preferably with lots of foliage, and emerge from late April to early June. Adults will fly to find the first-emerging canola crops.

“If beetles are active and a crop is stressed and not growing, it may be faster and more economical to spray borders two times as opposed to the entire field,” Rempel says.

Check labels for required intervals between sprays (usually around a week) and the allowable number of sprays per crop per year. For example, Decis can be applied three times, Pounce and Sevin XLR can be applied twice and malathion can be applied only once. A rotation of different products may give growers some insight into which ones work best in certain scenarios.

3. Achieve coverage

Flea beetle insecticides do most of their work through contact. Uptake through ingestion of insecticide on canola tissues is considered a “bonus.” Contact requires coverage, and coverage requires adequate water and appropriate nozzles.

For water, start with at least 10 gallons per acre. Higher water volumes — 15 to 20 gallons per acre — can improve results when striped flea beetles are the more common species, and on a cooler, windy day when flea beetles have moved down to feed on stems or the underside of leaves.

For nozzles, most products call for a medium nozzle. Check labels for specific recommendations because not all labels are the same. Tank mixing flea beetle insecticide with herbicide can reduce insecticide efficacy because low-drift herbicide nozzles, which are a good practice for some herbicides, produce a coarse spray droplet that may not provide efficient coverage or flea beetle contact for top results.

4. Spray when flea beetles are active

This is related to coverage. Flea beetles are most active when weather is warm, dry and calm. These are good conditions for spraying. In rainy, cool weather, flea beetles often take shelter in the soil and don’t feed as much. In rainy, cool conditions, expect lower efficacy.

5. Consider the temperature effect on insecticide efficacy

On hotter spray days, malathion and Sevin XLR may provide better results than pyrethroids (Decis, Pounce, Perm-UP and others). The malathion label recommends a minimum temperature of 20 C. The Sevin label includes this statement: “Best control is achieved when product is applied in the heat of the day when insects are actively feeding.”

Pyrethroids, on the other hand, have restrictions for application in higher temperatures. For example, FMC staff make the following statement for Pounce: “The recommendation is not to spray when temperatures exceed 25 C. If applications need to be made (or risk crop failure) when temperatures are at or above 25 C, manage the risk and set up for success: increase water volumes, make nozzle selection and boom height adjustments to reduce evaporative losses, and spray in the cooler parts of the day.” Research from the 1970s (Harris and Kinoshita, 1977) showed that pyrethroids were 2.6 times more potent at 15 C than at 32 C.

For Canola Watch agronomy tips on flea beetle management and how to make the spray decision, please check the Insects section at canolawatch.org/fundamentals.

Flea beetle management resources

The Canola Council of Canada has resources to aid you with flea beetle management. The following are three fundamental articles to help you better manage flea beetles in your fields. 

• Flea beetle management tips
• The flea beetle spray decision: 8 steps
• How to assess leaf area loss from flea beetles

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For maximum yield, canola should be cut at 60 per cent seed colour change on the main stem — or later. This gives seeds on side branches time to firm up and contribute to yield. Based on a survey of canola growers at the end of 2020, about half of swathed canola acres are swathed too early for maximum yield.

When combining starts, CCC agronomy specialists recommend drop pans to measure losses and a little extra time to adjust combine settings to keep losses to one per cent, or less.

And, finally, to limit storage losses, check bins regularly — even if canola seems to be at low risk for spoilage.

Here are three questions on the harvest and storage theme. Answers are provided at the end of the article.

Question 1. When combining a thin canola crop, losses out of the back of the combine can increase if settings are not adjusted. Which of the following is one adjustment to consider if crop volume is less than usual?

A. Open up the concave spacing
B. Reduce ground speed
C. Reduce fan speed
D. Set the sieves to almost closed

Question 2. The Prairie Agricultural Machinery Institute (PAMI) recently studied canola storage in large 25,000-bushel bins. Which of the following was an important discovery from this study?

A. Storage risk with large bins is reduced with a gravity-driven spreader to level the grain peak.
B. Safe storage recommendations developed 20 to 30 years ago do not apply to large bins.
C. To keep canola safe in storage, it should not be kept in bins larger than 5,000 bushels.
D. Typical fans may not provide the required airflow when large bins are filled to the top.

Question 3. The following four factors can all increase the spoilage risk for canola in storage. Which one was particularly noteworthy for Harvest 2021?

A. Green dockage
B. Hot canola
C. High-moisture canola
D. Weed seeds

Combine settings

A thin crop reduces “grain on grain threshing,” which is an important part of efficient combining. Increased ground speed and narrower concave spacing could increase grain on grain threshing. With less material going through the separator combine, a lower fan speed should reduce the number of seeds blowing out of the back. Before making any adjustments, measure losses out of the back of the combine. Then go through these changes one at a time to see what works to reduce those losses.

[PODCAST] Between the Rows: Tipping the scales, combine calibrations, in (bin) monitors ye trust, oats in vogue

The Harvest chapter at canolaencyclopedia.ca has details on how to measure combine losses, and the Combine Optimization Tool at canolacalculator.ca will walk you through appropriate settings for canola.

When it comes to storage, the first goal is to move air through the bin to cool grain and remove any moisture “sweating” from the seeds. This requires airflow. For more about the PAMI study on airflow in large bins, about storage risk factors, like green dockage from canola regrowth, and many other storage tips, please check the Storage chapter at canolaencyclopedia.ca.

Finally, please visit canolawatch.org and sign up to receive Canola Watch email updates.

Quiz answers: 1 (C), 2 (D), 3 (A)

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Pest management begins with regular scouting. In a survey of 1,000 canola growers last year, the Canola Council of Canada (CCC) learned 45 per cent of those surveyed scout their fields at least once a week. CCC agronomy specialists would like to see that number closer to 100 per cent because pest issues can flare up quickly and timely management is key.

Pest management is the bread and butter of the CCC’s Canola Watch emails, which provide timely agronomy tips weekly throughout the growing season. The emails also include a quiz to add a little fun to the learning process. To continue that theme, here are four quiz questions to test your knowledge on yield robbers. Answers are provided at the end of the article.

Question 1. The pre-seed window is a critical time to control kochia as 80 per cent of kochia seedlings emerge before the crop. Because all kochia populations in Western Canada are considered resistant to ALS inhibitors (Group 2) and many have resistance to glyphosate, dicamba and/or fluroxypyr, a tank mix is highly recommended. When targeting kochia, which is a recommended tank mix for pre-seed glyphosate?

A. Group 1 clethodim
B. Group 3 trifluralin
C. Group 6 bromoxynil
D. Group 14 carfentrazone

Question 2. Hot weather can reduce insecticide performance. For example, the label for the pyrethroid Decis (active ingredient deltamethrin) says, “Do not spray under a strong temperature inversion, or when temperature exceeds ______ as this will result in a reduction in control.”

A. 25 C
B. 31 C
C. 34 C
D. 37 C

Question 3. The CCC’s Canola Research Hub report for a recently completed study called “Validation of lygus and other insect pest thresholds in commercial farms throughout Alberta,” says the main accomplishment of this study is the validation of a new threshold for lygus in canola of ______ lygus per sweep.

A. 1
B. 2-3
C. 5-10
D. 10-20

Question 4. Blackleg infection that occurs at this crop stage is more likely to cause yield loss. What is the stage?

A. Cotyledon to four-leaf
B. Six-leaf to bolting
C. Bud to flowering
D. Late flowering to pod

Focus time and inputs

Canola growers can find all kinds of things in their fields that affect yield. The key is to focus time and inputs on the most important yield loss factors. Scout each field regularly to see what pests are likely to cause the greatest loss. If sprays are necessary, check labels for rates, timing, water volumes, tips to improve efficacy and pre-harvest intervals.

An important consideration for any insect spray decision is the economic threshold. This is the point at which insect damage will start to cause economic loss. By spraying only when pest numbers exceed the thresholds, growers eliminate the cost of unnecessary sprays and protect the large population of beneficial and non-pest insects also present in their fields.

The Canola Encyclopedia has detailed information on all major diseases, weeds and insects of canola, including scouting and management tips unique to each of them.

Canola Watch also has timely tips based on field observations across the Prairies each week through the growing season. Sign up for the email updates at canolawatch.org.

Quiz answers: 1 (D), 2 (A), 3 (B), 4 (A)

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It also helps when stands are uniform in number across the field and uniform in staging. This uniformity makes pest management and harvest timing easier, and can also add to yield, especially if stands are below the target.

In CCC’s Canola Watch emails, which provide timely agronomy tips weekly through the growing season, we use quizzes to make agronomy fun. To continue that theme, here are three quiz questions to test your knowledge on canola plant establishment. The answers are provided at the end of the article.

Question 1. One way to meet the target stand while also improving the return on investment for seed is to increase the percentage of seeds that emerge to form plants. What is the typical emergence percentage for canola crops in Western Canada?

A. 10-20 per cent
B. 30-40 per cent
C. 50-60 per cent
D. 70-80 per cent

Question 2. Canola seeded into cool soil takes longer to germinate than canola seeded into warm soil. Research from Agriculture and Agri-Food Canada in Beaverlodge, Alta., measured the pace of canola seed germination based on soil temperature. In soil at 8 C, the study found it took about five days for all seeds to germinate. In soil at 2 C, what percentage of seeds had germinated after five days?

A. Zero per cent
B. 10 per cent
C. 25 per cent
D. 50 per cent

Question 3. Plant density can influence days to maturity. CCC’s Canola Encyclopedia cites one study showing canola crops with 20 to 30 plants per square metre (two to three per square foot) will branch up to four times more than those with 70 to 140 plants per square metre (seven to 14 per square foot). This extra branching can delay seed maturity up to ___ days, depending on environmental conditions.

A. 3
B. 7
C. 14
D. 21

Canola calculator

Using the Canola Calculator on the CCC website, canola growers can find various tools to set seeding rates based on seed size, target stand and estimated emergence percentage. That same site also has the Canola Counts survey, a citizen science program the CCC launched last year. Participants enter data from a specific field, including plant count per square foot, seed size (grams per thousand) and seeding rate (pounds per acre). The calculator provides the emergence percentage for that field.

Canola Watch has lots of tips on seeding rates and how to increase emergence percentage. Find articles and sign up for timely email updates at canolawatch.org.

Quiz answers: 1 (C), 2 (A), 3 (D)

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When I shared the results, my colleague Clint Jurke, agronomy director for the Canola Council of Canada (CCC), said, “We have some work to do.” That’s because one of the CCC agronomy priorities is to encourage farmers to make seed decisions based on the best traits for each field. For most farms, that probably means growing more than two different hybrids each year.

At CCC’s Canola Watch, we like quizzes as a way to share agronomy knowledge. Here are four quiz questions to test your knowledge on canola seed traits. Answers are provided at the end of the article.

Question 1. Choosing cultivars with different days to maturity can spread out the harvest window. One strategy to ensure a noticeable difference in harvest date is to seed earlier-maturing cultivars __________.
A. At a higher seeding rate
B. After seeding later-maturing cultivars
C. Before seeding later-maturing cultivars
D. Without any seed-placed fertilizer

Question 2. If blackleg severity is increasing to the point where yield loss is likely, a grower will want to switch to a cultivar with a different major gene for blackleg resistance. When it comes to major resistance gene selection, what is the foundation for an informed decision?
A. A blackleg race identification test
B. Stem clippings to identify the presence of blackleg
C. If the field had a cultivar with resistance group C, switch to one with resistance group D
D. Don’t grow canola on that field for the next three years

Question 3. A new pod shatter rating system coming this fall will rate a canola cultivar’s level of pod shatter resistance. The rating scale goes from one to nine, with one having the highest risk of shatter and nine having the lowest risk of shatter. The system includes two checks and 45H33 is a “four.” The other check, L255PC, has what rating?
A. 5
B. 6
C. 7
D. 8

Question 4. The CCC recommends clubroot resistance even if clubroot doesn’t seem to be a major problem in the area. What is the primary reason for this recommendation?
A. Early infestations can be missed for years while susceptible hosts multiply spores to catastrophic levels.
B. All seed companies have clubroot-resistant cultivars, so why not?
C. Everywhere on the Prairies is at risk for clubroot, and clubroot resistance can prevent it from arriving on your farm.
D. Clubroot resistance eliminates the need to scout and follow crop rotation.

Cultivar choice

If a farm has 10 canola fields, it doesn’t make logistical sense to have a different cultivar for each field. What does make sense is to keep notes on each field and see how a different cultivar may help in certain circumstances. With regard to clubroot and blackleg, for example, it may make sense to switch up resistance genes if severity levels are rising in a field. The disease section at canolaencyclopedia.ca has lots of detail on blackleg and clubroot management.

To compare cultivars based on days to maturity, use canolaperformancetrials.ca data. To find cultivars that yield relatively well under a wide range of conditions, use the site to identify those with consistent results year to year and site to site.

Finally, please sign up to receive Canola Watch, the timely and free CCC agronomy emails. The short, sign-up form is at canolawatch.org. The site also has an article called “Choose the right cultivar for each field.” While most seed decisions are made by now, this information will help with last-minute decisions for this year and in planning for 2023.

Quiz answers: 1 (C), 2 (A), 3 (D), 4 (A)

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