Kochia, a long-time headache for southern Manitoba farmers, is now popping up as far north as Foxwarren and Dauphin, said Jeanette Gaultier, a technical services specialist at BASF.

“It’s just an ongoing issue. It’s there,” Gaultier said at Manitoba Ag Days 2025.

WHY IT MATTERS: Kochia is no longer confined to southern Manitoba, advancing north at a rapid pace, and has a biology seemingly primed to overcome herbicides farmers might come to rely on to control it.

More than a decade ago, Agriculture and Agri-Food Canada (AAFC) scientists predicted kochia’s northward march as they modelled how warming temperatures would affect weed distribution.

“I can say that their predictions are absolutely true,” Gaultier said.

The weed’s spread is compounded by growing herbicide resistance. Farmers can already assume Group 2 and Group 9 herbicides won’t work on Manitoba kochia populations, experts warned. Small pockets of Group 4 resistance exist, but have been thankfully slow to spread.

More concerning is the rapid progression of Group 14 resistance. About 20 per cent of tested kochia populations now resist Group 14 herbicides, according to recent findings from AAFC researcher Charles Geddes. This chemistry has been crucial for controlling the weed in recent years.

There is also new concern over Group 10 resistance pushing up from the south. At St. Jean Farm Days in early January, North Dakota weed specialist Joe Ikley noted they have been seeing more kochia escapes after being sprayed with glufosinate.

“We see escapes almost every year,” Ikley told attendees of that farm show.

“Can we prove those ones to be resistant, yet? It’s just a matter of time … until we get a population that is indeed resistant.”

For managing kochia, farmers must shift to multiple modes of action that actually work, not just tank-mixing products when only one is effective, Gaultier said.

Effective options include Groups 3, 4, 5, 10, 14 and 27 products used in combination programs. Group 15 herbicides offer some suppression when mixed with other products.

Mechanical control another strategy

Beyond chemicals, Gaultier praised farmers who are taking physical action against kochia patches.

“I was pleasantly surprised this fall driving around and how much mowing I saw of patches,” she said. “This is amazing. We are throwing in some non herbicides with some cultural management. This definitely prevents seed set.”

One farmer even bailed and burned kochia patches.

“I think this is a great way to help. You’re probably still getting some seed set, but it’s helping,” Gaultier said.

Kochia requires a proactive approach starting with pre-emergent herbicides, according to Manitoba Agriculture weeds specialist Kim Brown.

“With kochia, you have to be proactive versus reactive,” Brown said at Ag Days.

She recommended products like Authority and Valtera, which can be applied as pre-emergent residuals, or products like Authority Supreme, Fierce or Voraxor Complete.

Pay attention to application instructions

For Liberty applications, Brown stressed the importance of proper water volume, a point that cannot be compromised.

The recommended label rate in Enlist corn and soybeans for Liberty 200 SN is 1.0 litre of product combined with 2.4 litres of liquid ammonium sulphate (AMS), applied in 20 gallons of water per acre.

“That is not negotiable. That is how you use that product is a contact herbicide. You have to give it every chance you can to make it work,” Brown said.

She also warned against spraying kochia too late, even with effective products. She described a field where glufosinate initially killed kochia, visible as “burnt, crispy bits,” but the weed regrew because of timing and lack of crop competition.

Crop competition can cut kochia pressure

Kochia has the advantage of early emergence; and heat, drought and salt tolerance. It also spreads seed moderately well. But the weed has weaknesses too. It’s not very competitive against established crops, and seeds’ lifespan in the soil short-lived at just two to three years.

“It has a really short seed bank, and this one maybe helps us, maybe not,” Gaultier said.

Brown presented research from Geddes showing how cultural practices dramatically reduce kochia pressure.

In a four-year rotation of wheat-canola-wheat-lentils, simply narrowing row spacing from wide rows to nine-inch rows and doubling wheat seeding rates made a stark difference: an 80 per cent decrease in kochia biomass and a 63 per cent reduction in the seed bank.

Switching from spring wheat to winter wheat in the rotation proved even more effective. Winter wheat emerges early enough to compete with kochia right from the start.

“This winter wheat comes up first thing in the spring. Despite the fact that kochia is a warm season weed, it is up really, really early,” Brown said. “Something like winter wheat can compete quickly.”

Adding a short-term forage crop like alfalfa/meadow brome, where the crop is cut before seed set, is also a good option.

“Winter wheat reduced biomass by 64 per cent, and by putting alfalfa/meadow brome, it took out 99 per cent of the kochia,” she said. “So if you could make that work, that is a really good option.”

Northern farmers urged to remain vigilant

The message for all Manitoba farmers, but especially those in central and northern regions: keep your eyes open.

“Even if you live north of the No. 1 (highway), the further north you go, keep watching for kochia,” Gaultier said.

“Just even driving around, people are seeing in the ditches some of the kochia,” she said. “I think in the south, I probably have a pretty good idea where kochia is. It’s everywhere.”

— With files from Robert Arnason

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The partnership pairs Geco’s predictive mapping tools with Gowan’s line of soil-applied herbicides in a collaboration aimed at helping farms take a more deliberate, patch-based approach to weed control over multiple seasons.

WHY IT MATTERS: Seeing weed pressure ahead of emergence can make herbicide decisions more targeted and cost-effective.

Geco’s announcement includes two offerings tied to the partnership. The company is launching a new three-season predictive-mapping subscription, and growers who sign up through a Gowan representative will receive one additional field map at no extra cost.

“Our technology enables the question: If you could know where your most problematic patches are and where they are spreading to, what could you do differently? That’s what our technology makes possible,” said Greg Stewart, CEO of Geco.

How predictive mapping works

While blanket applications and spot sprayers respond to weeds already visible in-season, predictive mapping works ahead of emergence by using multi-year imagery to identify the areas most likely to develop patches. That allows farms to be proactive with treatments, rather than reacting after they’ve already gained ground.

A grower wanting a map begins by sharing a field boundary with Geco, often through a platform like John Deere Operations Center. If they don’t have a boundary available, Geco can make one for them. From there, Geco pulls every usable satellite image of that field from the last five growing seasons and runs them through tools designed to distinguish crop from weeds across the full season.

That multi-year history is what drives the prediction. Stewart said the key isn’t ultra-high-resolution imagery as much as having dozens of images per season and several years of history to reveal how weed patches shift over time.

The history shows where weeds tend to emerge early or flush late, and where patches persist. The resulting prescription can be exported straight into a sprayer, granular applicator, drill or variable-rate seeding tool.

“We look at a field, understand where weeds have been and where they’re going, and from there the farm decides what to do,” he said.

Geco has calibrated its system by comparing predictions against drone imagery, spot-sprayer data and human scouting across many fields.

Because the algorithms used to make these calibrations and predictions are proprietary, Stewart was tight-lipped about their inner workings. But while they play a big role in the process, he says the real challenge is fitting the technology into a farmer’s season.

“It’s not usually the math that breaks these technologies,” he said. “It’s how well you solve a real-world problem.”

That means making sure the system fits farm reality. It must mesh with timing at the end of the season and fold naturally into a grower’s weed-control plan. Those practical points tend to matter more than the complexity of the algorithm.

That’s also where partnerships come in. Predictive maps don’t work in isolation; they need to line up with the herbicides and practices growers are already using in the field.

Many early adopters were already using chemistries such as ethalfluralin and triallate (the active ingredients in Gowan’s Edge and Avadex) on their worst kochia and wild-oat patches. Those products are expensive to blanket across entire fields, and predictive maps help target them only where they’re most likely to deliver a return. So, the collaboration made sense for both companies.

But herbicides are only one part of the equation, said Stewart. Once the map is made, growers still need a plan for how to use it: which products to place where, when to increase seeding rates and how to tackle the “problem-child” areas that keep showing up year after year.

“It’s the agronomist and the farmer who put together that strategy,” he said.

For Warkentin, predictive mapping works best on fields with well-defined patches like those same “problem-child” zones mentioned by Stewart. Once he receives a map, he reviews it with the grower to confirm the predicted zones match field history and scouting. He then adjusts rates, creates the prescription file and loads it into the sprayer or applicator.

There are still some practical limits — the kind Stewart refers to when he talks about real-world barriers. For example, some older spreaders can’t run prescription maps. Fortunately there is an easy workaround: growers can load the files into Google Maps. However, Warkentin says timing is a more stubborn problem for farmers.

“The best time to look at these maps is after harvest, but that’s also the busiest time of year,” he said. “By the time fall work is done, there’s very little time left to get maps made up and implemented.”

For farms using higher-value soil-applied products, the economics work well. Targeting only the worst 20 or 30 per cent of the field makes premium herbicides more economical and reduces total chemical use. Farms using lower-cost products may see less financial benefit, since the price of generating a prescription can outweigh the savings from variable-rate application.

However, Stewart noted that most growers use the maps to intensify control in the toughest patches — not necessarily to cut total inputs.

Either way, Warkentin says growers who used the maps were pleased with the results.

“The system isn’t perfect, and producers know there will be a few small misses,” he said. “But overall the people who’ve used it have been happy with the results.”

For weed scientist Charles Geddes of AAFC Lethbridge, predictive mapping fits within a broader integrated weed management approach. He sees it helping growers make more deliberate decisions about where to invest their time, herbicides or cultural practices.

“I see this as another tool in the toolbox farmers have at their disposal,” he said.

Weed pressure is becoming harder to manage due to expanding herbicide resistance and weather variability that affects herbicide performance. Geddes says predictive mapping can help farmers plan where residual herbicides or added competition may provide the biggest returns. Using herbicides that stack multiple modes of action can be costly, especially on dryland farms, and applying them across full fields isn’t always justifiable.

“Predictive mapping lets farmers target herbicides or other practices where they’ll have the greatest impact,” Geddes said. “That can go a long way toward managing both costs and resistance.”

He also notes the technology adds some complexity. Prescription mapping requires growers to manage another layer of planning at a time of year when workloads are already heavy. That may limit adoption for some operations. But he expects interest to grow as farms gain experience and as more tools in crop production move toward AI-driven decision support.

That Prairie focus shapes where the technology goes next. Stewart says the company is now putting more emphasis on building partnerships with local retailers, agronomists and farmers to support longer-term, multi-season weed strategies. The Gowan partnership is just one example.

“We’re starting to partner with other retailers and independent agronomists across the region,” he said. “We’re really developing those relationships as much as we can these days.”

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The potato vine crusher was designed more than a decade ago to crush potato vines and kill European corn borer larvae. However, research scientist Andrew McKenzie-Gopsill wondered whether the same crushing action could also damage weed seeds before they are returned to the soil during harvest.

WHY IT MATTERS: A simple piece of potato harvest equipment, originally built for insect control, is showing how farmers could reduce weed pressure while harvesting without slowing their operation.

Early testing in Prince Edward Island focused on simulated harvest conditions. Potato plants mixed with common weed seeds were run through the crusher, and the remaining seeds were tested to see whether they could still germinate.

Seed size played a role in how consistently the crusher worked, McKenzie-Gopsill said. The crusher was originally designed to prevent damage from rocks and debris.

“It’s actually on springs, so that if a large piece of debris moves through it… it allows the rollers to move out of the way to accommodate that.”

This may allow some smaller seeds to escape during harvest.

Putting it to the test in the field

After lab testing, the research moved into real field conditions.

In 2023, biologist Nicolle MacDonald with AAFC’s Pest Management Centre worked with McKenzie-Gopsill to test the vine crusher during a working potato harvest.

They dropped mesh bags containing known quantities of weed seeds into the crusher as potatoes were harvested. They then recovered the seeds and monitored them for germination.

The field results showed reduced seed viability in several weed species, particularly those with larger seeds.

The crusher was also evaluated for how it fit into normal farm operations. It was found to not interfere with harvest speed, MacDonald said.

“It doesn’t really slow down operation at all with modern tractors.”

One tool in a bigger toolbox

Both researchers emphasized the crusher is not meant to replace herbicides, but rather to support longer-term weed management by reducing the number of seeds added back into the soil.

“It’s really just to try to reduce your overall weed pressure,” McKenzie-Gopsill said.

MacDonald agreed, saying that relying on a single tactic can create new problems over time.

“An integrated approach is the best way to try and get the best control,” she said.

Built to be adapted

One advantage of the vine crusher is that’s relatively simple and adaptable compared with some large, high-cost harvest weed seed control systems used in grain crops. Farmers could further modify the design to improve performance, McKenzie-Gopsill said.

For MacDonald, the project reflects how innovation often comes from practical thinking.

“I always think farmers are the greatest innovators,” she said. “They can create solutions to problems, and can definitely modify and make what we designed better for their systems.”

The post Vine crusher can smash weed seeds while squashing potato pests appeared first on Manitoba Co-operator.

These are the facts, Manitoba Ag Days attendees heard during the 2026 show:

Wild oat pressure is increasing across Manitoba. Herbicide resistance widespread.

WHY IT MATTERS: They don’t have as much hype as kochia or waterhemp, but herbicide resistant wild oats are a quieter threat that continues to gain ground in Manitoba farm fields.

Weather patterns in recent growing seasons have favoured the weed, particularly outside of the Red River Valley, according to Jeanette Gaultier, technical specialist with BASF Agricultural Solutions Canada.

“In the last two years, there has been an uptick in wild oat, which is always problematic, but it just seems to be really loving the springs that we’ve had and really taking advantage,” she told the Ag Days crowd.

Even more worrying is the number of wild oats coming back as doubly resistant —neither Group 1 or Group 2 products are doing the trick anymore. The last province-wide weed survey, with data collected in 2022, found that every one of the 155 fields sampled had wild oats resistant to Group 1, and Group 2 resistance wasn’t far behind. A whopping 82 per cent of samples were resistant to both Group 1 and Group 2.

“So, the numbers are against you,” Gaultier said.

She cautioned, however, against assuming all products in those larger groups are useless. Resistance expression can vary.

“There is some variable, with lots of different mutations for these resistances, and you do get variable cross resistances,” she said.

Reducing seed set remains critical, particularly given the cost and limited availability of effective herbicides. Soil-applied products are increasingly important, since post-emergent options are limited.

Crop choice and rotation can also play a role, especially in crops that mature earlier.

“Growing something like peas or fall rye and winter wheat is actually a really great strategy, because you are actually capturing a lot of those seeds,” Gaultier said.

“There are no other post emergent options for wild oats, other than Group 1 and Group 2, but basically… the Group 1s and Group 2s are there, and they’re not working so good,” she said.

Brown also pointed to older cultural practices that farmers might associate more with their parents or grandparents, before modern herbicides were widely available.

Those forebears “used to delay seeding, used to do a bunch of tillage,” she said. “They didn’t have herbicides back then. And then, you seed later. The crop comes up fast and gets ahead of the wild oats.”

However, Brown and Gaultier agreed that no single tactic will solve the problem, and wild oats must be managed as part of a broader, integrated approach.

For more Manitoba Ag Days coverage, watch the Co-operator’s Ag Days landing page.

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Escapes of the tenacious weed were back in grain fields this year, despite the annual spring and in-season efforts to blitz spray them out of existence.

WHY IT MATTERS: Wild oats may not carry the red alert alarm of new noxious weeds like waterhemp, but they’re a widespread weed headache well known for shaking off chemical controls.

“The single biggest issue with wild oats is resistance,” said Manitoba Agriculture weed specialist Kim Brown. “If we lose …our ability to use Group 1 and Group 2 because of resistance, you have no in-crop products left.”

That double resistance is becoming distressingly common.

Between 2019 and 2023, Agriculture and Agri-Food Canada and provincial ag departments embarked on an effort to measure herbicide resistance levels on the Prairies. In 2022, that survey came to Manitoba as part of a larger study of weed abundance across the province.

The resistance survey involved gathering, planting and spraying grass weed seeds with Group 1 and 2 herbicides. All the wild oats in the 155 fields surveyed for resistance turned out to be resistant to Group 1, and 82 per cent were resistant to both Groups 1 and 2.

Across all studied fields (over 700 across the province) that equated to 37 per cent of fields found with wild oats resistant to Group 1. Thirty per cent had Group 2 resistant wild oats, and 30 per cent had wild oats that were resistant to both.

Those doubly resistant populations were widespread across Manitoba’s regions. They were in the northwest and the southwest, scattered through central Manitoba and up into the Interlake.

The pattern is consistent across the region, said Charles Geddes, a national research scientist in weed ecology and cropping systems based in Lethbridge, and one of the names attached to the 2022 survey.

“We tend to see a similar story across the Prairies, where Group 1 resistance is by far the most abundant wild oat, and Group 2 resistance has been increasing, especially in recent decades,” he said.

Resistance rates climbing

The increase in Group 2 resistance stems from farmers switching herbicide modes of action when they discover Group 1 resistance, Geddes added.

“When many farmers find out that they have Group 1 resistance, they usually just switch over to relying on a Group 2, and that places greater selection pressure on that mode of action,” he said.

Adding to farmers’ concerns is emerging Group 15 resistance, which affects products like Avadex. The last assessment of Group 15 resistance across the Prairies, conducted between 2007 and 2009, found it in six per cent of surveyed fields.

Given increased reliance on these products due to Group 1 and 2 resistance, Geddes said it’s safe to assume that it has likely increased.

Wild oat weather

This year’s spring conditions may have contributed to a high level of weed escapes, including dry weather and windy days, Brown said. As such, some of those weeds might have dodged the spring burn off and many in-season applications.

“I think maybe a lot of weeds were not up yet … the sprays got put on, and then we started getting some rains in mid-summer,” she said.

Geddes agreed that weather conditions affect herbicide efficacy.

“In order for herbicides to have their intended activity on weeds in general, those weeds need to be actively growing,” he said. “The good news is that it also means there’s a greater likelihood that those survivors are susceptible, and not just those resistant.”

Farming with resistance

For farmers facing resistance issues, there are both proactive and reactive management strategies. One of these, Geddes said, is resistance testing.

“It’s one thing to assume that the population’s resistant because you had herbicide failure in the past, but resistance in wild oats can get complicated really quickly, and resistance testing kind of helps you understand what you’re dealing with,” he said.

With wild oats being primarily a self-seeding species, resistance patterns can vary significantly between neighbouring fields. Multiple resistance mechanisms can also create variable patterns of cross-resistance within herbicide groups.

“You may have resistance to, say, some Group 1 herbicides, but not others, and that means that there, you might still have some level of control from those remaining options,” Geddes said.

Management strategies hinge on reducing wild oat seeds returning to the ground. That could be a more diverse crop rotation, opening up more herbicide options, increasing seeding rates to boost crop competitiveness, or changing things up to include a winter annual or silage crop that is harvested early to disrupt the weeds’ lifecycle.

But most strategies on the list are for next year. Research suggests 60 to 70 per cent of wild oats seeds shatter from the plant and land on soil before spring wheat harvest, limiting the effectiveness of harvest weed seed control methods, Geddes said.

Fall is generally not the time to worry about wild oat control, since they’re annuals that have already set seed, Brown said.

“This is a time to evaluate and say, ‘okay, why did we have such an issue?’”

Wild oats present unique challenges

For non-chemical fall management of other weeds, Brown suggested tillage and potentially cover crops, depending on moisture conditions and the length of the fall growing season.

“Tillage, and the right kind of tillage at the right time, is … a really, really good tool,” she said.

The Manitoba resistance survey was last conducted in 2022, with the next survey planned for 2026, continuing on a five-year cycle to track the progression of resistance across the province, Geddes said.

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They were robots, used artificial intelligence and killed weeds with laser beams.

WHY IT MATTERS: Energy-based robotic weed removal offers a solution to herbicide resistance and labour challenges for producers reliant on hand pulling.

Field-applied plant cell exploding technology was one of the cutting edge agricultural ideas presented at the Bradford AgRobotics demo day earlier this summer.

Tech entrepreneur David Tao, CEO and co-founder of Ontario-based BH Frontier Solutions, presented a compact BHF ElectricWeeder, while Dutch ag-tech firm Pixelfarming demonstrated a modified laser model.

Haggerty AgRobotics president Chuck Baresich explained that the Pixelfarming Laser One-i prototype, adapted for the Orio NAiO’s frame, arrived in March. NAiO is an autonomous field robot in its third year at the Ontario Crops Research Centre in Bradford.

It features six laser units that use high voltage to energize a carbon dioxide tube, creating a focused beam that boils the liquid inside plant cells, effectively destroying the plant. “The lasers will shoot forward and back,” explained Baresich. “It will determine the optimum angle as you’re moving forward to hit the various weeds.”

Rydan Chalmers, Haggerty AgRobotics Systems Engineering intern, used 35 images of multicoloured confetti to demonstrate how easy it is to program the interface’s crop module to target specific plants or, in this case, confetti colours for eradication. Baresich clarified that plant images at various growth stages and under different lighting conditions are necessary to develop a comprehensive crop model, noting that the rapid pace of technological advancement and the availability of open-source tools are accelerating the process.

“You can load five (models) at a time,” Chalmers explained. “We have a few examples we’ve been testing in the field. And you want to make sure you have the right laser selected, (and) how much energy is going to each laser.”

For the demonstration, Chalmers set the lasers to 80 per cent, which, while producing a satisfying flame-out, was excessively high because most weeds and grasses are effectively terminated at between 25 and 40 per cent power.

Baresich warned that there is a low chance of starting a small fire if a field is dry or of damaging a neighbouring crop if the heat isn’t properly adjusted.

The LaserOne-i’s speed and effectiveness are optimized for dime-sized plants or early emergence, as larger plants slow the machine significantly.

“When you have a very, very tiny weed, it takes only milliseconds of heat to cook that,” Baresich explained. “That’s how you get the speed of the machine up.”

Field trials comparing 90,000 weeds to a million weeds per acre showed a significant slowing of the machine due to the number of shots per second per acre, a common issue when dealing with grass because it’s prolific, Baresich said. Depending on the heat level and dwell time required to eliminate a plant, the three lithium phosphate batteries provide a four-hour runtime, with the ability to add additional batteries.

BHF ElectricWeeder is an autonomous robot that selectively kills weeds with high-voltage electricity. It is guided by artificial intelligence using an integrated multi-camera computer algorithm that differentiates between weeds and crops.

“The algorithms are trained to recognize the crop; anything different from that would be considered a weed,” Tao explained, adding that the crop model trains with 100 images, with shape and morphology changes requiring additional training.

The robot collects data automatically, improving the AI’s accuracy and increasing its speed without the need for farmer oversight outside of the initial RTK to plot out the rows.

“Once it detects the weeds, it will guide the robot arms underneath and basically target the weed and zap it,” explained Tao, adding it’s part of an onion crop trial at the research centre.

During the demo, the robotic arms moved swiftly and methodically through the crop, unleashing an electric current that often produced a visible puff of vapour as the weed’s cells burst.

The key difference between the ElectricWeeder and other robotic options is its ability to dispatch weeds at any size and growth stage.

“It has two modes of operation tailored towards both low weed density fields and high weed density fields,” Tao explained. “It will maintain the same efficiency at killing weeds.”

The 1.2-tonne machine can weed up to 10 acres an hour and operate in most weather conditions 24/7, but like traditional iron, mud can be problematic.

“A bit of rain, a bit of drizzle, a bit of moisture is fine, but not too much,” he said. “Not like a muddy kind of pouring rain where you have ponds in the soil.”

The ElectricWeeder comes in autonomous, tractor-pulled, and tractor-liftable models, with coverage from five to 20 feet and swath widths of 60, 120, and 240 inches, plus an adjustable row spacing of 60 to 88 inches. The sub-millimetre precision and 99 per cent weed kill rate make it more efficient than a 100-person hand crew.

Tao said the US$150,000 commercial versions will ship near the end of the year.

Robot weed control will never be a one-time pass, said Baresich. “Part of the economics of the machine is how many times do I have to go through that same field, and can I get it done?” he shared. “In comparison to hand-weeding crews, where the costs are $500 to $1,000 an acre, these are very economical to run.”

He admits that chemical weed treatment remains cheaper; however, in cases of herbicide resistance and hand pulling, the ROI of laser or electric weeders pencils out.

“I think the reality is that even though the ROI might not work, we’re going to be forced into the robotic technology just because of weed resistance,” said Baresich.

The post Lasers and artificial intelligence: welcome to high-tech weed control appeared first on Manitoba Co-operator.

Sheila Taillon, a Saskatchewan range management extension specialist, conducted a two-year experiment as part of her master’s studies.

A PhD student is now continuing the five-year study on how fertilizer could increase parasitism of arbuscular mycorrizal fungi to control the invasive spurge in native grassland.

WHY IT MATTERS: A cost-effective control method for leafy spurge could improve millions of acres of grazing land across the Prairies.

Taillon told a recent webinar that leafy spurge is highly dependent on AMF, which are soil micro-organisms that form on plant roots and help plants increase nutrient uptake. In return, the spurge plants share their fats and sugars.

She said this relationship is beneficial to leafy spurge because it improves growth, helps produce seed and provides drought and pathogen protection.

Leafy spurge a tough pasture weed

Leafy spurge has invaded millions of acres and caused both ecological and economic damage by reducing the number of species available to grazing animals. It out-competes native grasses for light, water, nutrients and space, growing up to one metre tall.

It is typically found in sandier soil and mainly in grasslands but also riparian and shrubby areas. It is rarely found in crop land.

“It doesn’t particularly care for that annual cultivation,” Taillon said.

However, it is hard to control because, similar to dandelions, it contains a milky white latex that isn’t palatable to most cattle. Sheep and goats graze it, and leafy spurge beetles are also used to control it.

“That’s problem number one. If it’s not being grazed, then it just keeps growing,” Taillon said.

“Problem number two is that it produces an abundance of seeds. But the thing that makes leafy spurge so challenging to control is its deep rhizomatous, or spreading, root system.”

The roots can reach three metres deep and spread five metres each year; fragments smaller than 2.5 centimetres in size can regenerate.

Taillon said herbicides can be effective, but there are only a limited number available for use on grassland.

She said previous studies found AMF can become parasitic in nutrient-rich soil, taking resources from the spurge plants. It’s where the idea of using fertilizer to create that environment and increase parasitism emerged.

New leafy spurge control

Her work looked at the use of 2,4-D ester, a non-residual herbicide, as well as residuals Navius Flex and Tordon 22K, and applications of nitrogen, phosphorous, micronutrients and combinations of the three.

The full experiment included 360 plots on four native prairie sites all invaded by leafy spurge. They were in the dark brown and black soil zones of Saskatchewan, at St. Denis, North Battleford, the Manitou pasture south of Marsden and Grenfell.

The herbicides were applied in 2022, while the fertilizers were applied in 2022 and 2023.

“What we found was that the residual herbicides controlled the leafy spurge so well that it was challenging to see how the effects of the fertilizer were working,” said Taillon.

In addition to spurge control, the study looked at forage quantity and quality and species richness.

Taillon posed several hypotheses:

• That phosphorous and and micronutrients would reverse the AMF relationship from beneficial to parasitic, especially when combined with herbicide.

• That the applications of herbicides and fertilizers would increase grass growth and forage quality.

• That loss of plant species would be minimized using the non-residual herbicide but potentially increased using fertilizer.

Her study found 2,4-D provided moderate control while Navius and Tordon provided multi-year control in both types of soils.

The nitrogen and micronutrient combination, rather than phosphorous and micronutrients as hypothesized, reduced the leafy spurge compared to other treatments but not necessarily to the control.

Taillon said fertilizer effects were significant at the plot level of three-by-three metres but not at smaller levels.

‘We may be able to enhance control of leafy spurge using fertilizers, though further research is needed,” she said.

All three herbicides contributed to increased grass biomass compared to the control, which Taillon said was likely an indirect result through reduced competition from spurge rather than direct use of herbicides.

Biomass increased with the fertilizer treatments, and forage showed increases in protein.

To no one’s surprise, the use of herbicides, particularly Tordon, decreased the number of species; there was no effect from fertilizer. Taillon said using 2,4-D could provide openings for other species in the first year.

“We found limited support for use of fertilizers for controlling leafy spurge,” she said.

“At the plot level we saw significance with the nitrogen and micronutrient treatments, suggesting that it may be possible to use fertilizer to enhance control of leafy spurge.”

Further research is needed to determine how rich the soil nutrients need to be to flip the AMF association from positive to negative, she said.

Taillon also said the use of tools will depend on land management goals and environmental considerations. Conservation goals may differ from livestock production goals, she added.

The post Fertilizer to fight leafy spurge appeared first on Manitoba Co-operator.

“One of the reasons why we’re struggling so much with herbicide resistance and some of the weeds that we’re trying to kill is that we have not had any new herbicides, or any new herbicide groups for a very long time,” she said earlier this spring.

WHY IT MATTERS: Weeds like kochia and waterhemp have been flagged for their ability to leave herbicide in the dust.

Some Group 4 herbicides have been in use since the Second World War, almost 80 years. Many individual herbicides have been developed over the intervening decades but the last new herbicide group to appear was in the mid-1980s. There have been some new families within Group 4 and Group 14 chemistries, she noted.

“Even if we have new products, they’re still killing weeds in the same way, because they’re still part of an existing group. The problem is that we don’t really have any new groups that kill weeds in a new way,” Brown said.

“If we start to get resistance to that group, it’s probably going to be resistant to a lot of products in the different families in that same group,” she added.

Last year, news broke that agri-chemical company FMC had submitted regulatory applications for an herbicide with a new mode of action, Group 28, in eight countries. It got the green light in Peru this April. That product registration, however, is targeted only for rice.

Developing resistance

Weeds do start with some resistance to an herbicide, even if it’s initially low enough that the weed dies.

“Over time, as we keep using that herbicide and, if it’s working really well, and it’s killing all the ones that aren’t resistant to it, then over time, the ones that are resistant are going to be the ones left behind,” Brown said.

When full blown herbicide resistance is seen in the field, the herbicide product will cease to work.

Brown said the only thing a farmer can do to prevent resistance is to try different methods of killing weeds and stretch out the time before the herbicide become ineffective.

She recommended farmers visit the Prairie Weed Monitoring Network website. The site houses weed survey results and resources for farmers and agronomists.

One tab details which weeds are resistant to which herbicides. There are many weeds, for example, developing resistance to Group 2 herbicides, while Group 4 resistance is rising in weeds like cleavers, wild mustard and kochia. Green foxtail has been showing resistance to Group 3 herbicides.

“We know we have some unconfirmed populations of (resistant) red root pigweed as well, and so we’ll be working on getting official confirmation of those,” she said.

“If you’ve been using a lot of Group 3s in the past, watch the red root pigweed. You may start to see some of those breakthroughs that Group 3s aren’t working very well anymore.”

Resistance can also come on quickly, Brown warned.

Monitoring weed resistance

The last weed survey was done across the Prairies in 2022 with the next one to be conducted in 2026. The surveys have been going on since the late 1970s.

“We basically do an abundance survey,” Brown said. “We rank our weed species by relative abundance, which is a combination of relative frequency within the field, relative uniformity within that field and density.”

Seven hundred fields are included in the survey. Last time, 155 were tested for resistance. The surveyors made sure surveyed fields included the top six crops in the province: canola, wheat, soybeans, oats, green corn and barley.

“We also did a few fields of peas, beans and sunflowers,” she said.

The number of herbicide resistant weeds have increased over the years of monitoring. The 2022 survey found that 75 per cent of fields surveyed had at least one herbicide resistant weed. That was up from 68 per cent in the survey before, which had much smaller coverage, Brown noted.

Based on a survey farmers filled out, herbicide resistant weeds were estimated to cost Manitoba farmers about $81 million in lost revenue or in added costs from using extra herbicides each year, she said.

Manitoba’s weed hit list

The top ten resistant weeds in Manitoba right now include green foxtail, buckwheat, volunteer canola, lambs quarters, red root pigweed, yellow foxtail and barnyard grass species.

Volunteer wheat, wild oats and round-leaved mallow had dropped in the previous survey, but this was due to wet springs and late seeding.

“If we have a normal year and more normal seeding times, I expect to see wild oats come back up in the ranking in the next weed survey,” she said.

Western advantage

Manitoba has always had more herbicide resistance than Saskatchewan and Alberta, Brown noted.

She recommended farmers keep a copy of the province’s Guide to Field Crop Protection handy. The document is available at all department service centres.

Brown also recommended farmers watch their labels. Some products are pre-seed and some are pre-emergence, meaning that producers can apply after seeding, but chemicals must be applied before the crop breaks ground. Farmers should make sure they are reading the labels on their herbicides and using them correctly, she said.

She also suggested websites including the Herbicide Resistance Action Committee. As well as resistance information, the website has details on cover crops, crop competition, harvest, weed seed control and integrated weed management. This website does not mention spraying, she warned, but focuses on other methods of controlling weeds.

Another recommended website was Weed Smart from Australia, which features farmer testimonials and weed control strategies.

The post Farmers, don’t get trapped by herbicide resistance appeared first on Manitoba Co-operator.

That’s not a real quote, but it could be. Too much information can actually stifle action, and integrated weed management is no exception.

In that case, which options should the producer key in on when sorting out which of the wide and varied list of weed management tools they could potentially use are the most valuable?

WHY IT MATTERS: Spring has sprung and, with it, weed seedlings are poking out of the ground.

When you ask weed management specialists for their top three, there are a few common answers.

“Overall, my top three would be seeding rate, row spacing and crop rotation,” said Charles Geddes, weed research scientist with Agriculture and Agri-Food Canada in Lethbridge, Alta.

Crop rotation introduces a number of practices to keep weeds off balance. Some crops establish faster, grow taller or have winter or perennial seasons and varying harvest times. A crop with an earlier harvest can mean weeds are cut off before they set seed. Later harvest can prevent fall establishment of winter annuals.

Crop rotation can also add variability to the farm’s herbicide package, but another expert, Shaun Sharpe, says the variability may be less than the farmer thinks.

“I am not convinced our diverse crop rotations provide the in-crop herbicide options necessary to manage the weeds we’re facing,” said the weed research scientist with Agriculture and Agri-Food Canada in Saskatoon, Sask.

Fall-applied products and pre-seed burnoff will enhance the herbicide rotation options, he added.

Geddes’s other two choices — higher seed rate in combination with narrower row spacing — provide faster ground cover in the spring, leaving weeds less room. Natural crop competition is a valuable step in suppressing weed growth.

“Of course farms cannot easily change row spacing at this stage of the season,” says Shawn Senko, agronomy specialist with the Canola Council of Canada, “but it is something to consider when choosing seeding tool configurations for the future.”

Kim Brown, weed management specialist for Manitoba Agriculture, selected the same three tools as Geddes. Brown said the rise in row-crop soybean acres in the Manitoba presents a challenge for crop competition. She’d like to see narrower rows for the other crops.

“I can understand why drills have 12- and 15-inch spacing, but this is not cool from a weeds perspective,” she said.

Sharpe included scouting and sanitation in his top three, putting his top picks in alignment with Breanne Tidemann’s.

“My personal top three in terms of things farmers can easily do this year without a massive change to their system or requiring a large investment would likely be seeding rate, scouting and sanitation,” said Tidemann, weed research scientist with Agriculture and Agri-Food Canada in Lacombe, Alta.

Sanitation can include cleaning combines after finishing a particularly weedy field and using weed-free seed.

In the vein of relatively easy steps, Tidemann also highlights the importance of following herbicide labels, “with an emphasis on weed size.”

A farm might follow all other steps on the label, but if the weeds are too large for the label rate, control likely won’t happen.

Tidemann includes one other note: “We tend to focus on the multiple options or packages because we know that more items stacked together works better,” she said.

Herbicides alone don’t cut it.

What producers are doing

“We have a herbicides-first approach to weed management, driven mostly by a history of fairly effective results,” Senko said.

As herbicide resistance becomes more and more of an issue, though, attention is shifting to the broader, integrated management approach.

The Canola Council of Canada ran a grower survey after harvest 2024. One question asked which integrated weed management practices growers follow. The most common answer was tank mixes and rotating herbicide groups. Second was using earlier or later seeding dates. Third place was claimed by increasing crop competition, including options narrower row spacing and higher seeding rates.

Results suggested that farmers are closely aligned with the weed specialists. Effective herbicide tank mixes are important. Crop rotation in combination with narrower rows and higher seeding rates are good starting points to reduce weed competition and selection pressure for weeds with herbicide resistance.

If scouting shows a continued rise in weed competition though, it’s time to add other practices from the integrated weed management list.

“While these top three are important, the right mix of practices really depend on the situation,” Geddes said.

The integrated weed management short list

The list of integrated weed management practices can be intimidatingly long. Weed specialists tend to like the crop rotation step in combination with higher seeding rates and narrow row spacing. Here’s a short list of options and how they play into weed control.

Make the crop more competitive

1. Use higher seeding rates.

2. Vary the seeding dates.

3. Seed at a shallow depth.

4. Use narrow row spacing.

5. Choose taller crops.

6. Place fertilizer where crop can access it before weeds. Don’t broadcast.

7. Use seed treatment to promote faster growth.

Keep weeds off balance

1. Use crop rotation to introduce crops that compete in different ways, including winter crops and perennials.

2. Tank-mix effective herbicides from different chemistry groups.

3. Consider strategic tillage, especially for concentrated areas with large or challenging weed populations.

Prevent weed problems before they start

1. Scout each field before and after herbicide application.

2. Keep records, including which weeds are present in a field, which herbicide products are used, rates used and weather conditions at application.

3. Follow herbicide labels and check restrictions to improve results.

4. Use sanitation, including combine clean-out and clean seed.

5. Invest in harvest weed seed control, such a combine chaff mills.

For more details on each step, read “Integrated weed management: Best practices” at canolawatch.org.

Jay Whetter is a communications manager with the Canola Council of Canada.

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