That was the core message Brendan Metzger delivered at the Manitoba Agronomists Conference.

The chemistry itself, he said, has not suddenly changed. What has changed is the cropping context around it, particularly as glufosinate moves into systems that expose management mistakes more quickly and more consistently.

WHY IT MATTERS: With glufosinate use expanding on the Prairies, careful management will matter more in slowing resistance pressure.

Metzger, a senior herbicide biologist with BASF, said the risk facing Liberty is real and accelerating. Glufosinate resistance has already emerged in other regions, and Prairie farmers are now using the product in crops and rotations that strip away many of the safeguards that once kept resistance at bay.

Reports of glufosinate-resistant waterhemp in several U.S. Midwest states and kochia escapes being reported in North Dakota, suggest resistance is now close at hand.

Liberty still works, he said, but the margin for error is narrowing.

Glufosinate longevity

To understand why management now matters so much, Metzger first walked agronomists through why glufosinate avoided resistance for so long in Western Canada, especially when compared to glyphosate.

Glufosinate was introduced in the mid-1990s, at roughly the same time glyphosate-tolerant crops entered the market. Yet while glyphosate resistance emerged relatively quickly, Liberty avoided that outcome for nearly 30 years.

“It’s been largely a success story,” Metzger said.

“There’s been no documented cases of resistance to glufosinate in Western Canada.”

He said that longevity had little to do with glufosinate being inherently resistance-proof. Instead, it reflected how and where it was used.

For much of its commercial life, glufosinate lagged behind other herbicides in total acres treated. Lower overall use meant lower selection pressure on weed populations. Just as importantly, most glufosinate applications in Western Canada occurred in canola.

Canola’s competitiveness played a quiet but critical role.

Rapid early growth and quick canopy closure suppressed escapes and reduced the number of weeds exposed to sub-lethal doses. That cultural weed control helped mask small mistakes that might otherwise have contributed to resistance.

“So we have the cultural weed control aspect working in our favour as well,” Metzger said.

Rotation added another layer of protection. Even in relatively simple canola–wheat systems, glufosinate was rarely applied back-to-back on the same acres. Breaking up modes of action further reduced resistance risk.

Those factors combined to give Liberty a long runway, Metzger said, but that runway is now shortening.

Competition pressure

Metzger warned that as soybean acres expand, so will selection pressure on glufosinate.

While Liberty-enabled canola already accounts for a large share of Prairie acres, Metzger said the more consequential shift is happening in soybeans as seed companies move aggressively toward glufosinate-tolerant platforms across North America.

Roughly a quarter of western Canadian soybean acres are expected to be Liberty-enabled in 2026. Metzger said that expansion is being driven largely by widespread glyphosate resistance, with glufosinate long viewed as a relatively underused alternative.

Unlike canola, soybeans are far less competitive.

Wider row spacing and slower canopy closure mean fewer escapes are hidden. Weeds that survive an application are more likely to remain visible, reproduce and contribute seed back to the soil.

Corn shares some of those same characteristics. In those systems, Metzger said, poor management is more likely to translate directly into resistance risk.

Another concern for Liberty is that its mode of action amplifies the consequences of poor application.

Glufosinate is a contact herbicide. It only affects weeds it lands on, and those weeds must receive a lethal dose to be killed. That makes the product especially vulnerable to sub-lethal exposure.

“A sub-lethal dose, whether that means not adding enough product to the sprayer or not getting it to the target at the proper dose, can select for resistant individuals over time,” said Metzger.

Risk management

Delta T, which relates spraying conditions to air temperature and humidity, is particularly important for water-based formulations such as Liberty, said Metzger.

Compared to oil-based products, glufosinate droplets take longer to cross the leaf cuticle, increasing the risk that moisture evaporates before the active ingredient can move into the plant.

Metzger said Liberty remains an effective tool, but he cautioned against assuming it will behave the same way it did when most acres were in canola.

As more soybean and corn acres shift toward glufosinate tolerance, resistance risk will be shaped less by the chemistry itself and more by how consistently it is managed.

Coverage, timing and weed size are no longer details to fine-tune, Metzger said. They are the difference between preserving the tool and quietly selecting for trouble.

Liberty still works, but on today’s Prairie farms, it no longer forgives mistakes.

The post Weed resistance closes in on glufosinate appeared first on Manitoba Co-operator.

The invasive species has been downgraded from a Tier 1 to a Tier 2 noxious weed in 28 municipalities where it has dug a foothold, Manitoba Agriculture has said.

WHY IT MATTERS: Manitoba agronomists and farmers have been watching warily as waterhemp has spread farther into the province in recent years.

The change to Manitoba’s Noxious Weeds Act reflects the reality that waterhemp can no longer be considered rare or isolated in these areas, said provincial weed specialist Kim Brown.

“It has been confirmed in 28 RMs in Manitoba (and) as of 2024, it’s rapidly spreading,” she said.

The weed remains classified as Tier 1 in rural municipalities where it has not yet been confirmed.

New control requirements for affected areas

Under the revised classification, small infestations of waterhemp in Tier 2 areas must still be destroyed. However, for larger infestations, the requirement shifts from destruction to control measures aimed at preventing spread, Brown told participants at a Manitoba Agriculture Crop Talk webinar June 23.

Manitoba considers anything 20 acres or under a small infestation.

“As a Tier 2 weed, we still must destroy those small infestations so that (it) cannot be allowed to stay … because we know there’s an awful lot that are there (and) they’re coming in loaded with resistance already,” Brown said.

Waterhemp was first spotted in the province in 2019.

It is a known headache for farmers thanks to its tendency to develop herbicide resistance. It’s also difficult to scout for early enough, since younger seedlings are easily confused for more common and less problematic weeds.

By the time farmers know what they’re up against, the weeds have outgrown their more vulnerable stages, or they’re resistant to the chemicals being used against them anyway. The only remaining options, Brown said, are hand mowing and weeding.

Herbicide resistance creates control challenges

Waterhemp’s biology gives it a step up against herbicides. It is a dioecious species, with both male and female plants that cross-pollinate. This allows for a lot of genetic diversity, the Manitoba Crop Alliance website notes. Resistance genes can spread rapidly through pollen transfer.

At the same time, the weed is noted for its prolific seed production and its ability to germinate easily. Once the plant figures out how to beat the chemistry, there’s a lot of offspring to pass the trait down to.

“We know that glyphosate is not working,” Brown said. “Lots of Group 2s don’t work. Our Group 14s may not be working. Group 5s may not work, and we know we have some Group 4 resistance showing up as well.”

Manitoba’s waterhemp findings are still mostly in the southeast, although there have been isolated cases in unexpected locations, including the Dauphin area and the RM of Ellice-Archie.

“The birds basically are eating the weed seeds down south and depositing them as they fly north. And they can also move in flood waters,” Brown said.

The weed can also be spread through dirt or seeds hiding in nooks and crannies of farm equipment.

Key waterhemp identification features

Manitoba Agriculture has some advice for farmers trying to determine if they’ve just got more redroot pigweed, or if there’s something worse lurking in their fields.

“Sometimes (waterhemp) leaves are a bit longer and skinnier than a regular redroot pigweed. It can be kind of a darker, shiny green leaf, not all the time, but lots of times,” Brown said. “And the stems and the leaves and the petioles … which are the stems that attach the leaf to the main stem, those are very, very smooth.”

The cotyledons of young waterhemp plants also differ from other pigweeds. They are wider and more tapered. In other pigweeds, they tend to be long and narrow, shaped like a cigar.

Early detection and landowner responsibility critical

Under Manitoba’s Noxious Weeds Act, landowners and residents are responsible for controlling noxious weeds on their property, with enforcement handled at the municipal level.

Farmers should contact Manitoba Agriculture with suspected waterhemp sightings. Even small, initial infestations can quickly become overwhelming, Brown said.

“If you even start with a few plants on a field and do absolutely nothing, within three to four years, you can have that weed like a solid field, side-to-side. It’ll be corner-to-corner on that field.”

The post Too much waterhemp to destroy in parts of Manitoba appeared first on Manitoba Co-operator.

“I reach a fair number of farmers in this province, but we probably have 8,500 registered farmers, and we can’t reach them all. So, we rely heavily on the local agronomists and the local (retailers) to put on information events for their farmers. We are really thankful for that.”

Brown is the only extension weed specialist employed by the province, but that wasn’t always the case. When she was hired by the province in 1998, she was one of two specialists, and there have been as many as four in the past.

Why it matters: Weed concerns like waterhemp, Palmer amaranth and kochia have farmers on the lookout for herbicide resistance in Manitoba.

Brown was among speakers at the Manitoba Agronomists Conference in Winnipeg Dec. 11 and part of a panel discussion on weed management in Manitoba. She was joined by two private sector weed agronomists: Tammy Jones from Corteva and Jeanette Gaultier from BASF. Both are former weed specialists with the province. The discussion was moderated by the University of Manitoba’s Rob Gulden.

The role private sector agronomists play is critical, said Brown, especially when it comes to problem weeds like waterhemp.

“We’ve been trying to get that information out on waterhemp for a long time. Sometimes farmers need to hear it two or three times before it sinks in. A lot of those agronomists are taking that message back to their farmers.”

Gaultier, current chair of the Canadian Weed Science Society, said there is a concern about reduced weed research and extension across the country. Filling that gap will require broader collaboration among weed agronomists.

“When it comes to weeds, there’s no keeping secrets,” she said.

Jones concurred.

“It takes a village to manage all of these weeds, whether it’s kochia or whether it’s waterhemp, the same concepts apply.”

Herbicide resistance was the focus of the conference’s morning schedule, and Gulden steered discussion toward the panel’s favoured cultural weed control method — something they might recommend first for farmers.

Gaultier said boosting crop competitiveness is her first step. There are numerous ways to make crops competitive against weeds, like variety selection and seeding rates.

“All those decisions around your crop are pretty easy tweaks,” she said.

Brown said her focus is weed seed management.

“When we’re dealing with things like waterhemp, we talk about the millions and millions of seeds per acre that are going to be out there if you let even a few plants get away on you,” she said. “We have to start getting control on what’s happening with those weed seeds.”

She outlined several ways this can be achieved, from simple concepts like chaff tramlining and chaff carts to expensive but effective weed seed destructors.

Brown praised weed seed destructors as effective tools but noted “they’re not going to work every single time.”

They’re a tool struggling to gain ground with Canadian farmers. Earlier this year, an Agriculture and Agri-Food Canada researcher suggested only a few dozen units were in use nationwide during fall 2023. That compared to much higher use in Australia, where an extended spraying season has raised the profile of herbicide resistance issues.

Information from the Tractor and Machinery Association of Australia showed that 20-30 per cent of the combines bought in Australia in 2022 were fitted with seed destructors.

Weed seed destructors also tend to be less effective with weeds like wild oats, which drop their seed before harvest, conference attendees heard, but Gulden pointed out that even in those cases, the machines can play a role in weed control.

“The combine is probably the best weed spreading tool we’ve ever invented,” he said.

Even if a fitted seed destructor doesn’t get all weed seeds, “it’s containing that patch in that spot,” he added.

Gulden’s comment led nicely into Jones’ preferred cultural weed control method, patch management.

“If it’s a big patch, start at the edges and contain it, and then try to get it smaller. Get them early and manage them,” she advised. “Pull them out, cut them, mow them, burn them, whatever it takes.”

The post Building a culture of weed control appeared first on Manitoba Co-operator.

As of last year, 20 rural municipalities in Manitoba were affected by waterhemp. This year, even more were added to online maps, according to Kim Brown, a weeds specialist with Manitoba Agriculture.

“We’re basically seeing lots of waterhemp showing up again. We know we’ve got it in many places in the province,” she said during an Aug. 14 Crop Talk online seminar. “We know that waterhemp is moving north and west, but everybody needs to be watching for it.”

Why it matters: Waterhemp is spreading rapidly in Manitoba. It’s becoming herbicide-resistant and is hard to identify. Vigilance and diverse management are needed to control it.

Where waterhemp was already present, it’s spreading even more prodigiously, Brown added. It hasn’t yet appeared in the other Prairie provinces, according to the Manitoba Crop Alliance website.

Waterhemp has high genetic variability because it is dioecious, having distinctly male and female plants necessary for cross-breeding and seed production. Its herbicide-resistant traits spread quickly among plants through pollen.

“Most of the waterhemp (that) will be found in Manitoba is coming pre-loaded with resistance,” Brown said. The Manitoba Crop Alliance says waterhemp has already developed resistance to herbicides in Groups 2, 9 and 14.

Waterhemp can produce up to one million seeds per plant under low competition conditions, and the small seeds are easily transported through contaminated seed, straw, hay, farm equipment, manure, migratory birds and floodwaters.

The plant prefers warm temperatures with lots of sunlight and nitrogen-rich soils, where it can reach heights of three metres. It can continue to flower and set seed until the first frost arrives.

Brown said it is crucial that producers monitor for waterhemp, both in wide-row crops like corn, soybeans and sunflowers, and in denser cereal crops.

It’s even showing up in canola crops, where it can flourish in bare spots in the field, she added.

“They’re not in the body of the canola crop, but they’re just kind of lurking there right on the edge, and there (can be) a lot of plants there.”

Waterhemp has been a particular problem in soybean fields this season due to its early emergence, Brown said. It has most commonly been found in fields without pre-emergent herbicide application.

Since waterhemp can grow taller than soybeans as the season progresses, it is more easily spotted in those fields. It thrives in thinner areas, bare patches and along field edges. As the soybean canopy opens, waterhemp will continue to grow and become more prominent. Regular monitoring is recommended to detect and manage it early.

However, waterhemp can be tricky to spot. At times it can look like other pigweed species.

“Lots of times it does look like a pigweed, but sometimes the leaves are longer and narrower,” Brown said. “Usually they’re bigger, but that’s a little hard to tell too, because you don’t know when they’ve germinated.”

Waterhemp has a smooth, hairless stem, unlike other pigweed species. Its leaves also tend to be longer, narrower and glossier, but in Manitoba, it has been known to hybridize with other plants, making visual identification more difficult.

“This is a weed that is a real chameleon. It looks like a lot of different things, and so it’s hard to know just by looking at it until you get to know it well,” Brown said, adding she hopes the weed won’t become such a problem that producers across Manitoba get to know it by sight.

To prevent waterhemp, the Manitoba Crop Alliance recommends diverse crop rotation. Employing tank mixes with multiple effective herbicide modes of action, including soil-residual herbicides, can help prevent development of resistance.

Narrow row spacing, increased plant populations to promote faster crop canopy closure, and using strategic tillage will also help, since waterhemp germinates from near the soil surface. Post-spray scouting is essential for early detection.

Since waterhemp is classified as a Tier 1 noxious weed under the Manitoba Noxious Weeds Act, producers must immediately eradicate it. When in doubt about weed identity, producers should remove the plant and contact the province for DNA testing.

Vigilance is key, Brown said. If producers can root out waterhemp with the help of Manitoba Agriculture, it’ll be easier to stop its spread.

“You’ve got to be watching all of the areas around the fields — the edges, the ditches, not just within the body of the field,” she said. “We don’t want to have that much of it in the province yet, but we know its here. We’ve got to be watching.”

The post Waterhemp digs deeper foothold in Manitoba appeared first on Manitoba Co-operator.

The Manitoba Weed Supervisors Association (MWSA) recognizes this week by highlighting a few of the invasive plants considered to be a significant threat to the landscape of our province. Many of these invasive species are mistaken for wildflowers, but unlike native wildflowers, these species threaten agricultural productivity, waterways and natural areas.

The Noxious Weeds Act of Manitoba requires control or destruction measures for different invasive plants. A comprehensive list of noxious weeds is found in the Noxious Weeds Regulation, which ranks plants according to their threat levels and specifies the areas of the province where these levels apply.

The act requires that Tier 1 weeds must be eradicated without conditions. This includes current threats like diffuse and spotted knapweed, orange hawkweed, red bartsia, Palmer amaranth and tall waterhemp.

Tier 2 weeds are also a significant concern and include leafy spurge, common tansy, field scabious and nodding thistle.

The MWSA is comprised of weed supervisors individually employed by weed control districts formed by one or more municipalities. These supervisors are authorized through the Noxious Weeds Act to ensure problematic weeds are dealt with appropriately on all lands in the districts they cover.

The districts, first introduced in 1964, have developed programs to deal with invasive plants such as leafy spurge and red bartsia. Prevention measures, early detection and rapid response are all critical for protecting habitats and agricultural land from these types of invasive species.

Tall waterhemp (Ameranthus tuberculatus)

Waterhemp is native to the U.S., but was not considered a major agronomic problem until the 1980s. Herbicide resistance and changing production systems, including more corn and soybeans, reduced tillage. Greater reliance on herbicides for weed control favoured the “weediness” of this plant.

This member of the pigweed (amaranth) family can rapidly take over cropland and significantly decrease yields. Its native habitat is wet, low-lying areas, but it also grows well in drier areas. It thrives in reduced tillage and no-till environments. Watch for patches along field edges or near field entrances, as well as along ditches and waterways.

The plant typically grows six to eight feet tall with glossy, hairless and more elongated leaves compared to redroot or smooth pigweed. Waterhemp is well adapted to warm temperatures and intense sunlight and is capable of producing up to a million seeds per plant, which can germinate over the whole summer.

Waterhemp has very tiny seeds similar to redroot pigweed seed, making it easily transported via equipment, water flows or wildlife. It can also be a contaminant in seed lots.

Removing small patches of waterhemp prior to seed set and destroying the plants is one of the most effective strategies to eradicate this weed. Tall waterhemp populations can be resistant to multiple herbicide groups, making it very hard to control.

Waterhemp samples in Manitoba have been tested and confirmed resistant to three herbicide groups. This has serious implications for local producers.

New populations have been discovered since it was first detected in Manitoba in 2019. The latest distribution map from Manitoba Agriculture reported it in 19 municipalities as of 2023.

Palmer amaranth (Amaranthus palmeri)

Palmer amaranth is an aggressive, invasive weed native to the desert regions of the southwest U.S. and northern Mexico. It was accidentally introduced to other areas and has devastated crops in the southern U.S. and Midwest as it rapidly became herbicide resistant.

With the ability to emerge all season, grow two to three inches per day and set seed over the entire season, this highly invasive weed can drastically reduce crop yield. Infestations have slowly moved north through contaminated seed, equipment, animal feed and bedding, and in the digestive tracts of wild birds.

Palmer amaranth was first detected in North Dakota in 2018 and is spreading throughout the state. Considered to be the No. 1 weed in the U.S., this plant can grow 10-12 feet tall and produce one million seeds. Heavy infestations can reduce soybean and corn yields by approximately 80-90 per cent.

In the same family as redroot pigweed and tall waterhemp, Palmer amaranth can be difficult to distinguish from its cousins. Smooth-stemmed like tall waterhemp, its leaves are a little wider, more like redroot pigweed, but can be distinguished by the long petiole (stem-like structure that attaches the leaf to the main stem). Petioles of Palmer amaranth are longer than the leaves, while its cousins have shorter petioles. Long, snaky seed heads that can be up to two feet long are another distinctive feature.

Identification is crucial and removal of individual plants and small patches is critical to prevent this weed from establishing in our province.

So far, spread in Manitoba has been limited. Two plants were found in the RM of Dufferin in 2021; a single plant was found in 2022 in the same area. No new detections were reported last year.

Nodding thistle (Cardus nutans)

Nodding thistle is an invasive species accidentally introduced to Manitoba more than 100 years ago as a contaminant in forage seed. It grows as a biennial (two-year growth cycle), invading dry areas such as heavily grazed rangeland and coarse soils.

Its stalks and leaves have strong, sharp spines that can injure livestock. Animals will avoid it and graze elsewhere, giving the plant a competitive advantage.

Nodding thistle reproduces only by seed. In the first year, the seedling will develop into a large flat rosette. It will overwinter, then continue to grow to maturity in the following growing season.

Usually, the rosettes require adequate snow cover to survive the winter. That’s why nodding thistle patches are generally found in ravines or bluffs within a pasture.

As seed is its only means of spread, the first step toward management is cutting down the flowering stalks to destroy the seed heads. Later in the fall, once rosettes have established (around late September), apply a broadleaf herbicide to prevent maturation and seed set the following year.

Continue checking for and spraying new rosettes as they develop throughout the fall. This will provide a head start on control for next year. It’s important in the spring to look for and treat any rosettes before they start to form flowering stalks.

Nodding thistle is found primarily in southwestern Manitoba.

More information on invasive plants that are either threatening to emerge or already present in Manitoba can be found in the Noxious Weeds Act and the Noxious Weeds Regulation, by contacting your local weed district or the MWSA website.

The post Don’t yield to weed invaders appeared first on Manitoba Co-operator.

The two boogeymen of the weed realm were recent subjects of a successful resolution brought before the Keystone Agricultural Producers.

The motion, by ag diploma students from the University of Manitoba, seeks to have KAP lobby the provincial government for more supports into control strategies for the two noxious weeds.

Why it matters: Palmer amaranth and waterhemp are the villains of weed horror stories in the U.S., thanks to their prolific seed production, yield damage and propensity for herbicide resistance.

Palmer amaranth has only been found twice in Manitoba, both times in the RM of Dufferin. Waterhemp has dug a wider footprint. As of 2023, the province reported it in 19 municipalities, mostly in the southeastern corner. Both weeds have reputations as yield killers, with the ability to spread rapidly and resist herbicides.

Kim Brown, Manitoba Agriculture’s weed specialist, said her department has been doing extension work on the two weeds since 2019, bringing in speakers from Ontario and North Dakota where the weeds are more widespread.

“Every single talk I’ve done this winter … every single time I talk about waterhemp,” Brown said. “We’re trying to reach as many farmers as we can.”

Her team keeps up with research on the two pigweeds from areas where they are a noted problem. However, Manitoba-specific research is limited.

That’s a good news-bad news scenario. Little research means no information rooted in Manitoba’s growing conditions, but the main reason control strategies are hard to test is because there are few of the problem weeds to test them on.

Provincial regulations require that Tier 1 noxious weeds be destroyed whenever found, and their in-field presence has been sporadic so far.

“We certainly are not going to be seeding any of this down and having plots in it,” Brown said.

Manitoba Agriculture’s prevention strategies have included municipal partnerships to improve drainage in affected areas so that seeds are not deposited by overland flooding. Farmers have been advised to clean equipment, especially if brought from the U.S., and to be cautious with cover crop mix seed. That has been one method of spread in the U.S., Brown said.

Chemical companies have been asked about future research and confirmation that strategies used in North Dakota will work in Manitoba.

Control

Enforcement of the Noxious Weeds Act is the purview of municipal governments, Brown added. Municipalities either form a weed district, with a weed board and weed supervisor, or appoint a weed inspector. The province is in touch with weed supervisors and inspectors in areas where waterhemp has been found.

More prevention could probably be done with more manpower, said Laura Schmidt, a production specialist with Manitoba Pulse and Soybean Growers.

“We need people to both monitor for this weed and to actually research the effective management strategies,” she said.

For instance, the province could benefit from a more frequent weed survey. The most recent province-wide survey results are from 2016 and the survey before that was done in 2002.

It’s hard to distinguish waterhemp and Palmer amaranth from more benign pigweeds, Schmidt added. More extension work might be needed to help producers identify the harmful plants.

“We need to be actively monitoring for these weeds and destroying them,” Schmidt said. “If you do spot a pigweed in your field, you want to be feeling that stem. If it’s smooth, we need to get your agronomist involved or get an accurate identification.”

Manitoba Canola Growers members have access to identification testing through that organization’s Pest Surveillance Initiative Lab. Schmidt also suggested contacting Brown if suspicious weeds are found.

Crop rotation strategies are also likely be important, Schmidt said. Waterhemp struggles to compete in dense crop stands, as opposed to field edges or row crops.

“We do have this kind of dependence on chemical control measures, which aren’t going to work well for these weeds over the long term. This is also going to require a bit of a fundamental change to our traditional weed management strategies.”

The post The gaps in Palmer amaranth, waterhemp prevention appeared first on Manitoba Co-operator.

A resolution brought forward by University of Manitoba agriculture diploma students during KAP’s March advisory council meeting March 27 aims to give more support to farmers to beat back Manitoba’s growing problem.

Why it matters: Waterhemp and Palmer amaranth have well-earned reputations for prolific seed production and herbicide resistance.

The resolution would see KAP fund testing on the resistant tendencies of these noxious weeds, allocate resources to develop strategies against them (such as research into crop rotation, cover crops and reduced seed row width) and to fund work to find better herbicide options.

“We believe that this issue needs to be tackled with greater knowledge of how to scout for and deal with waterhemp and Palmer amaranth,” said one student, Nathan Krahn, of Rivers, Man.

The two pigweeds are both Tier 1 threats under Manitoba’s Noxious Weeds Act and both are relatively new to the province. Waterhemp was first confirmed in the province in 2016 and has since spread through eastern and into central Manitoba, and has popped up as far west and north as the RM of Dauphin near Riding Mountain National Park and RM of Ellice-Archie along the Saskatchewan border.

As of 2023, Manitoba Agriculture had confirmed waterhemp in 19 municipalities.

Palmer amaranth sparked alarm when it was first found in central Manitoba in 2021, but has yet to see significant spread. As of 2023, the RM of Dufferin was the only municipality with a confirmed Palmer amaranth incursion.

Both weeds pose serious yield loss risks due to their tendency to develop glyphosate resistance.

One student presenter, Brennan Friesen, farms in the Municipality of Rhineland, an area where waterhemp has been discovered.

“We haven’t seen it yet, but it’s just a matter of time,” said Friesen. “We just want to have a proactive solution instead of a reactive one.”

KAP board member Chuck Fossey asked the students if they were contemplating a mandatory action proposal, noting that Alberta regulates the frequency of canola rotations on the same field to stop the spread of clubroot. Students said they only hoped to get programs out to farmers.

The resolution passed with 92 per cent approval.

Other business

KAP president Jill Verwey gave an update on the three-month Imperial Oil pipeline shutdown, which had raised concerns about fuel supply in parts of the province.

“Fuel suppliers have assured stakeholders that there is no issue with fuel supply in Canada or the province, but that delays in delivery and price increases will remain potential concerns,” she said.

She added that agricultural needs are included in the fuel distribution planning process to ensure demands are met, and no significant impact to agriculture is expected.

Verwey highlighted KAP’s recent lobbying efforts, including its work on Bill C-234. If passed in Ottawa, the bill would exempt propane and natural gas for grain dryers from carbon pricing. The bill passed the House of Commons, was amended in the Senate to remove barn heating from the original document and, as of press time, was lingering in the lower chamber.

That bill has been a top priority for KAP for a while, Verwey said, adding the organization continues to engage with MPs, senators, industry stakeholders and KAP membership as the saga around the legislation persists.

“We are disappointed to see the Senate vote in support of the committee report that included some harmful amendments,” she said. “We will now lobby members of Parliament to reject the senator’s changes so that the bill is restored to its original form and sent back to the Senate for approval again.”

The post Farm organization takes aim at noxious weeds appeared first on Manitoba Co-operator.

“You’re going to hear a lot about this in the next few years because this is just going to become a bigger and bigger problem, but I really believe we can get out ahead of this and we can manage this,” she said.

Why it matters: Waterhemp is a tier one weed under the Noxious Weed Act and farmers are responsible for the weed management that comes with that classification if it is found on their fields.

Waterhemp is a growing concern in Manitoba. First spotted in 2019, it is starting to spread throughout the province. Recent reports identified it in soybean fields in the RM of Emerson-Franklin and the RM of De Salaberry, bringing the number of affected municipalities to 19.

The rapid spread is attributed to flooding and water movement, especially in drainage-prone areas.

Waterhemp is a tier one weed under the Manitoba Noxious Weeds Act. The act mandates the destruction of tier one weeds and places the onus on farmers to prevent their establishment.

“We have three tier one pigweeds on our Noxious Weeds Act,” said Brown. “We’ve got our waterhemp, our Palmer [amaranth], and our smooth pigweed. They’re on our list because, elsewhere in the world, they are resistant to glyphosate.”

Of those three, Brown said she is less concerned about smooth pigweed.

“We have some of this smooth pigweed naturally in Manitoba, but I don’t think that we have any glyphosate resistance here.”

Palmer amaranth

Palmer amaranth has yet to present a significant problem in Manitoba, though there is potential. That weed was first detected in Manitoba in 2021 in the RM of Dufferin. The latest information from Manitoba Agriculture indicates that municipality remains the only one where the weed has been found.

Palmer amaranth has earned its reputation as a yield eater in the U.S. Research out of Iowa State University suggests it can reduce soybean production by 79 per cent.

Palmer amaranth “has displaced waterhemp in a lot of places,” Brown said. “They’re not dealing with waterhemp anymore. They’re dealing with Palmer [amaranth], and it is worse.”

When to scout for waterhemp

Brown said waterhemp, like all pigweeds, is a warm season weed.

“So they don’t come up first thing in the spring when it’s cold and wet,” she said. It prefers a moderate to moist environment as well as high light intensity.

“This is why it is thriving in our row crops. It likes those wide rows of bare, black soil,” said Brown. “It’s hot; you’ve probably got good fertility in there, so this weed just loves that.”

Conversely, it doesn’t compete well beneath the canopy of a competitive crop. Waterhemp is not often observed in canola and wheat, but Brown warns it can still lurk, even if the crop planted that year doesn’t let it express itself.

“What’s saving our butts on this one is that we have other competitive crops in the rotation where it does not take off.”

Producers can expect the biggest waterhemp emergence in June.

“It begins emerging after the herbicide burn down in no-till, or the last tillage, whichever one you’re dealing with. And it continues to emerge throughout the entire growing season,” said Brown.

Even plants that emerge late in the fall can set seed.

“It can set seed within two weeks of emergence. Now, it doesn’t set a lot of seed [if it’s shortly after emergence] but, when you’re talking about a resistant plant, any seed is too much. We cannot let this thing set seed.”

Mature waterhemp is a prolific seed producer. Brown estimated that a big plant with no competition could set up to 4.8 million seeds.

In real field conditions, the total is not quite so high. Research out of Ontario suggests that waterhemp emerging at the same time as soybeans will have about 300,000 seeds. But if emergence can be stalled so it emerges 50 days after the crop, there will only be 3,000 seeds per plant.

“The plants were a lot smaller and they have a lot less seed,” said Brown. “This is good. We need to manipulate this. We cannot deal with thousands of plants per acre, each having 300,000 seeds.”

What to look for

When it comes to pigweeds, it’s hard to tell the mundane from the critical.

“All the pigweeds look alike, especially when they’re smaller,” said Brown. “It’s very hard to identify them visually.”

That’s a problem, since farmers should control waterhemp before it’s four inches tall.

“It looks like lamb’s quarters. It looks like a big ragweed,” she said. “I even find the plants that germinate late in the summer look a lot different than the plants that germinate first thing in the spring.”

Brown points out that Palmer amaranth, waterhemp, and smooth, spiny, red-root or Powell’s pigweeds look almost identical at emergence.

“When we get to the two-leaf stage, it’s no better. And, when we start to add a few more leaves, it pretty much still looks like a pigweed,” she said. “You know it’s a pigweed, but you don’t know which one at this point.”

Despite efforts to categorize young pigweeds by visual characteristics, no methodology has proven reliable.

“Sometimes waterhemp get[s] these longer, skinnier leaves, but not always. Sometimes they’ll talk about a little hair at the end of the leaf, but it depends. Sometimes they have a little ‘v’ mark in here like a chevron, like what’s on clovers, and some people will say, ‘oh, if it’s got that, it’s waterhemp or Palmer [amaranth],” said Brown.

“Nope, because I’ve seen red-root pigweed populations with that chevron. Sometimes it’s purple. Sometimes it’s white. You can’t go by any of those things.”

But one reliable method for eliminating at least one pigweed option is touch.

“Red-root pigweed is hairy and rough feeling,” said Brown, even when it is small. “I think it feels like really fine-grit sandpaper, but without the sharpness. So when you run your fingers up and down that weed and you run your fingers up and down that stem, it feels bumpy.”

All other pigweeds of concern are smooth.

“Waterhemp is very, very smooth. Sometimes you can see some really fine little hairs, but you never feel them. It just feels super, super smooth.”

For a resource on the different species, Brown recommends the Pigweed Species Guide put out by the Ontario Ministry of Agriculture, Food and Rural Affairs.

The post The problem with pigweeds appeared first on Manitoba Co-operator.

“As a basic starting point, I think every grower should seed at least three varieties. Every year. As a minimum. Hopefully more than that,” said Bohner, a soybean specialist for Ontario’s Ministry of Agriculture, Food and Rural Affairs.

Why it matters: Advice suggests that Manitoba growers might face problems if they hang their soy hopes on a single variety each year.

Bohner spoke about soybeans, yields and management of the crop at the Manitoba Agronomists’ Conference held in mid-December at the University of Manitoba.

A more diverse soy mix is the major difference between farmers who are getting ahead and those who call him, frustrated with their yields, he said.

To support his argument, Bohner presented data on soybean yield gains from 1942 to 2022 in Ontario. The average yield gain over those 80 years was 0.36 bushels per year. When that number is cross analyzed with soybean variety trials in Ontario, data shows most of the gain comes from plant genetics.

“When we plot our variety trials over the years, and they go back to the 1960s, the average response [increase] there is 0.33 bu.,” he said.

That suggests 90 per cent of yield gain, year over year, comes from genetic improvement, he argued.

“We don’t have exact numbers to tease that out. It’s a best estimate,” Bohner said.

That doesn’t mean on-farm practices like seeding date, fertility and weed control are meaningless. If a grower gets those wrong, there will certainly be an impact on yield.

But with yield capacity carrying such a heavy genetic component, Bohner said there is danger if the farmer bets everything on a single variety. That might not be the variety best suited for that farm’s conditions, region or soil type.

“That’s what I’m trying to push against. I think that’s a big mistake.”

Planting three or four varieties doesn’t “guarantee more bushels,” Bohner added, but the potential for gains are there. It will also help a grower understand what works on their farm.

Those three varieties don’t need to be evenly split, “but you should, for your own learning, have a few varieties in there …. It’s a nuisance. Let’s be honest. [But] it’s a good practice.”

Agronomics

Outside of the critical genetic choice, producers in both Manitoba and Ontario have been changing their field management.

In many parts of Ontario, for instance, producers are moving away from no-till soybeans. That’s due in no small part to the hassle of corn residue management earlier in the rotation. Corn yields in the province are huge, and managing those stalks becomes a massive challenge if a farmer hopes to plant soybeans after a 220-bu. corn crop.

“I’m not a big fan of tillage for soybeans, but I am a huge proponent of dealing with the residue …. Heavy residue is the enemy of big soybean yields,” said Bohner.

Most producers in his region of southwestern Ontario have “gone back to some form of incorporation, whether it is a high-speed disc or vertical tillage.”

Soybean growers in both provinces have also changed, or will soon change, their approach to weed control. For many years, they relied solely on glyphosate to keep weeds in check. Those days are over.

“At one time, people would just spray it and forget about it. Now, you spray, go back and see if you have any misses,” said Dennis Lange, soybean and pulse specialist with Manitoba Agriculture and another conference speaker.

Lange showed a map illustrating how waterhemp, first discovered in Manitoba in 2017, has rapidly spread across the province.

“We now have 22 confirmed [municipalities] that have waterhemp. It’s a little scary when you walk out there and see those fields.”

Almost all waterhemp in Manitoba is resistant to glyphosate, and some plants may be resistant to multiple herbicides. It is designated as a Tier 1 noxious weed in Manitoba and must be destroyed when found.

Waterhemp can be managed, but experts have warned soybean growers and other farmers that they need to adapt.

In 2023, Lange said, farmers who had waterhemp issues tended to plant Enlist or Xtend soybeans. Those varieties tolerate two or three types of herbicides. Enlist beans have tolerance for glyphosate, 2,4-D choline and glufosinate. Xtend beans can tolerate glyphosate, dicamba and glufosinate.

When producers opted for glyphosate alone, “all of a sudden, they gave us a call,” Lange said.

The “waterhemp plants were up to [their] knees …. Glyphosate only can run you into problems.”

– Robert Arnason is a reporter for The Western Producer.

The post Seeding one soybean variety a ‘mistake’ appeared first on Manitoba Co-operator.

Weeds have had ample time to grow after harvest, making them prime targets for herbicide.

Why it matters: As harvest winds down, attention turns to field preparation for 2024.

There are also fall-germinated weeds to contend with.

“We want to get after those weeds,” said Brown. “We have no idea what we’re looking at going into the winter when it comes to moisture. We do not want these weeds to use up valuable moisture.”

September onward is often pegged as a good time to tackle perennial weeds. Species such as thistles, dandelions and quack grass often top that list.

Pre-harvest applications will have helped, the weed specialist noted, but producers can’t always get a good spray application and even if they do, weeds may crop up again at the end of the season.

“There is lots of kochia in lots of fields,” Brown said. “It’s just getting worse and worse. It’s probably our number one weed across the province.”

The weed germinates early and farmers may face a serious kochia problem next season, given the number of good-sized plants still standing in fields.

Winter annuals

Winter annuals are another weed category to tackle. These include narrow-leaved hawksbeard, night-flowering catchfly, white cockle, stinkweed and cleavers.

“A winter annual germinates in the fall, goes dormant over the winter, and then pops up first thing in the spring and is able to start growing before anything else does, so it’s robbing nutrients and moisture,” Brown said.

“They’re really hard to get with an in-crop spray because usually, by the time we get around to doing those in-crop sprays, they’re far too large to control.”

Summer annuals

As for summer annuals, “I’m concerned about our pigweeds because we are seeing more resistance,” added Brown. “Even just our red root pigweed — a lot of that is Group 2 resistant now, and we don’t want those setting seed at all.”

All pigweeds can germinate early in spring but they also germinate late in the fall and can set seeds.

“We don’t want that happening, especially when we’re talking about waterhemp,” she said.

This weed, now being found across the province, is resistant to glyphosate, as well as Groups 2, 5 and 14 chemistries.

“Those are the only tests we’re doing, so we don’t know what else they’re resistant to, but we do know they are coming in with resistance already,” Brown warned.

As a Schedule 1 weed under the Noxious Weeds Act, waterhemp requires diligence to control.

“Where those weeds have been cut off, they’ll regrow from below where they were cut, and they will still set seed, so that’s something that we’re really concerned about,” said Brown.

Other weeds

Wild oats and lamb’s quarters also continue to present problems.

“If we’ve got regrowth, we always seem to have lots of lamb’s quarters around harvest time,” she said. “Whether or not we can get those weeds with a fall pass just depends on how much regrowth we can get from them.”

Ideally, farmers should allow four to six weeks of regrowth before spraying.

“That’s a long time, so that doesn’t always happen. But basically, you need to have green, growing tissue. Four leaves minimum, or maybe six for some of our perennial weeds.”

While spraying for perennials should be underway, Brown said farmers can wait a little longer for winter annuals to ensure they’ve fully emerged.

“We still haven’t had a really hard killing frost across the province. We’ve had little bits of frost here and there, but it hasn’t been that bad yet.”

Based on recent forecasts, Manitoba could reach mid-October before getting a killing frost.

“That gives us a lot of time, but you need to make sure you get that weed control done,” said Brown. “You want to put those products on before we get that killing frost.”

When spraying for weeds, temperatures must be above 8 C for a few hours after application. Brown suggested mid-morning or early afternoon passes to meet that threshold.

In regions with light frost, farmers will have to assess whether there’s enough growth to make spraying worthwhile.

“You need to have about 60 per cent of the leaf tissue alive, so we can spray quite late in the fall,” said Brown. “Even after some light frost, we can still spray, but you need to have living plants to be able to take up those products.”

She suggested waiting two to three days after a frost to assess the smaller weeds.

“If they’re very wet-looking and black-looking within a day or two, you know that they’re not worth spraying anymore.”

More time will be needed to assess bigger weeds.

Growers who plan to pull iron this fall will also have to be patient. Brown suggested waiting at least three days (and longer if possible) after spraying any product that needs to reach the roots. This gives the product time to get where it needs to go.

Most products are either recommended or must be sprayed with glyphosate, and Brown said it’s important to keep an eye on rate.

“Low rates don’t cut it if there’s very little leaf material, so depending on the weeds and depending on how much leaf material there is, you may need to bump those fall rates up.”

Scouting is always recommended, particularly as more herbicide resistant weeds appear.

“We need to make sure we set those fields up for success the following spring,” said Brown. “That’s the big message. We can’t forget about weed control once the combines are done.”

*Update: Kochia was mistakenly listed as a perennial weed. We apologize for any confusion this may have caused.

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