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.

Longevity so far

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.

Less competitive

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 Management decisions matter more as resistance pressure builds on glufosinate appeared first on Grainews.

Aaron Hager, a University of Illinois weed scientist, reported last month that Illinois had several locations where waterhemp had developed resistance to glufosinate, a commonly used herbicide in North America.

Other states in the region have the same problem.

Why it matters: When and wherever they arrive on the Prairies, weeds with Group 10 herbicide resistance will further limit growers’ control options, especially against weeds already resistant to multiple other herbicide groups.

“Four states in the U.S. (including Illinois) are all going to come out (soon) with glufosinate-resistant waterhemp,” said Joe Ikley, a weed scientist at North Dakota State University.

Ikley made the comment Jan. 7 at St. Jean Farm Days, a farmer conference at St. Jean Baptiste in southern Manitoba’s Red River Valley.

The news from the U.S. Midwest is concerning because farmers are running out of options to control waterhemp, a member of the pigweed family. It has already developed resistance to seven different modes of action.

For farmers on the northern Great Plains, it’s a matter of time before waterhemp with resistance to glufosinate is confirmed, Ikley said.

“If it can evolve resistant to a herbicide in Illinois, there’s no reason it can’t do it in North Dakota or the Canadian Prairies.”

Waterhemp was first discovered in Manitoba in 2017, and it’s now present in a wide geography within the province.

It hasn’t been confirmed in Saskatchewan, but weed experts are asking farmers and agronomists to maintain a close watch for the troublesome weed.

While waterhemp is an extremely difficult weed, a bigger risk to western Canadian farmers would be glufosinate-resistant kochia.

Repeated doses

On the market in Canada since 1993, glufosinate ammonium today is the only member of Group 10, nitrogen metabolism inhibitors.

It’s sold on the Prairies mainly by BASF under the brand name Liberty, though several generic versions have come to market since the chemical’s patent expired.

In North Dakota, farmers apply glufosinate to 10 million acres of land every year, Ikley said.

So, kochia plants are receiving repeated doses of glufosinate, and resistance is on the horizon.

More North Dakota farmers are reporting escapes, where the herbicide fails to kill a kochia plant. If glufosinate is applied to 100 kochia plants in field and 95 die, the remaining five plants are “escapes.”

“We see escapes almost every year,” Ikley said.

“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.”

It’s impossible to predict when glufosinate-resistant kochia will arrive in North Dakota or the Prairies.

But Ikley is particularly worried about canola growers, who rely on glufosinate to keep weeds in check.

InVigor hybrids dominate the canola acres in Western Canada, which are genetically modified to have tolerance to glufosinate.

“The issue, when I look at kochia and canola right now, is that the options are glyphosate or glufosinate,” Ikley said.

“And we (already) have widespread glyphosate resistance (in kochia).”

At St. Jean Farm Days, an agronomist delivered a blunt assessment of the risk.

If glufosinate-resistant kochia appears on the Prairies, farmers are “hooped.”

The post Glufosinate-resistant waterhemp appears in U.S. Midwest appeared first on Grainews.

As if those weren’t enough to contend with, another potential threat to crops will soon rear its ugly head: weeds. Grainews recently spoke with experts in the three Prairie provinces about the weed outlook for 2024 and what growers should know as they prepare for the upcoming season.

Manitoba

The 2023 growing season in Manitoba was mostly a good one in terms of weed control, thanks in part to relatively dry conditions which limited the proliferation of some weeds in many parts of the province.

Still, 2023 wasn’t without weed challenges, according to a specialist with Manitoba Agriculture.

Kim Brown says some pockets of the province received large dumps of rain midway through the season. As a result, the province saw a “flushing” of warm-season breakthrough weeds later in the summer after herbicides had already been applied. Weather conditions also made applying in-crop sprays particularly challenging.

Manitoba received relatively little snow this past winter. Combined with above-average temperatures this spring, that could bode well for the province’s weed outlook in 2024, Brown says.

“Right now it’s looking like we could have a very early spring and I think that would be very good, to get our crops in early, get them up and get them growing, get them to where they’re competitive. An early spring (can help) growers get ahead of the weeds,” she says.

The dry conditions facing most parts of the province can lead to an increase in certain weeds. Brown says that’s likely to increase salinity levels in some regions — and some weeds, particularly kochia, thrive in those dry, saline soil conditions.

“We have trouble establishing crops in these areas and the crop that does establish is not nearly as competitive as it could be and weeds like kochia start taking off,” she adds.

Kochia has been the most serious weed threat in Manitoba for some time and Brown expects that to be the case again this season.

“Our No. 1 weed problem that’s in front of us right now is kochia and it’s getting worse and worse,” she says.

“It’s moving into areas where it really wasn’t a big problem before. It does well in saline soils and of course we are seeing our salinity increasing after some dry years. We have net upward movement of water in the soil profile because we’re just not getting those rains from the top. Salts move up with the water, so they accumulate at or near the soil surface.”

There are several tools growers can use outside of tank mixes to fight kochia. Brown says the most effective of those is to maintain as diverse a crop rotation as possible. Another is to promote crop competition that can help choke out many weed threats.

Last year was a bad year for pigweeds, such as redroot pigweed and waterhemp. The latter is a becoming a serious concern as it appears to be popping up in more and more locations in the province each year.

“We’ve got it in a good chunk of the province now and we’ve got some fields that had some pretty high infestations last year. That’s very concerning because that is a weed that can displace pretty much all of our cropped acres,” Brown says.

Part of why waterhemp is so challenging to deal with is that it comes pre-loaded with resistance. It’s already resistant to most products available to fight it, including Group 2 and 9 chemicals and some Group 14s, by the time it shows up in a field.

Brown says it’s important growers use pre-emergent products with a residual component as much as possible. In the case of soybeans, she also recommends using tank-mix partners such as 2,4-D choline or dicamba with glyphosate for the best results.

Another weed of increasing concern for growers in Manitoba is foxtail barley, a type of bunchgrass that is found in high saline areas. It can show up in most crops, but especially those that are sensitive to salinity such as soybeans and dry beans. The good news with foxtail barley is there are several products available to effectively deal with it.

Growers in Manitoba also need to be aware of the risk of herbicide carryover — a risk that’s expected to be higher than usual because last summer was so dry and the rains that fell last fall didn’t contribute to microbial breakdown, because soil had already cooled by that time.

Brown stressed that it’s crucial for producers to read the labels of any herbicide products they use — and to record how much rain fell on their farms.

Most product labels will say how much rainfall is needed for the chemical to be safe for sensitive crops following herbicide application. Growers may need to wait a little longer before putting certain crops back onto a field after a hot, dry year, she says.

Saskatchewan

Hot, dry conditions hit much of Saskatchewan in 2023. As a result, some weeds thrived while others had limited impact on crops.

The weed outlook for the province in 2024 will depend largely on the type of weather received in coming weeks, says the acting weed control specialist for Saskatchewan’s Ministry of Agriculture.

Cory Jacob says another hot, dry summer likely means weeds that thrive in those conditions will be challenging again. Those weed threats include kochia, Russian thistle, redroot pigweed and green foxtail.

Kochia was a concern for many producers in the province last season due to those hot, dry conditions and is likely to remain so this season, he adds.

“We’ve got kochia that is flourishing,” he says. “That was a big one that a lot of producers were talking about and discussing last year.”

Cooler temperatures and more precipitation would mean more robust populations of cooler-season weeds such as wild oats, wild mustard and possibly volunteer canola.

While pigweeds such as waterhemp and Palmer amaranth have yet to be detected in Saskatchewan, they are definitely on the radar, Jacob says.

“We don’t have them yet here in Saskatchewan, but they’re on the watchlist that we’re monitoring for, just to see when they show up here and if we can be quick to contain them and make sure they don’t spread quickly once they get in the province.”

Jacob urges any growers who detect either weed in their fields to contact the provincial ag ministry to provide confirmation.

“Don’t ignore it. Don’t put your head in the sand. If you can control it early on, it’s a lot easier than if it becomes a larger issue.”

Herbicide resistance should continue to be top of mind for Saskatchewan producers, says Jacob. That’s why they need to keep on top of which chemical groups are still effective and can be part of an effective tank mix, he adds.

Growers may also want to consider agronomic tools such as seeding rates and narrower row spacing to help crops be more competitive against weed pressure.

Herbicide carryover could also be an issue in parts of the province this season, Jacob says. Farms from west-central Saskatchewan down to the southwest corner of the province likely have the highest risk, as those areas have been extremely dry the past several years.

“I would say that’s the area for caution and concern.”

Alberta

Hot and dry conditions in much of Alberta in 2023 helped restrict weed emergence to a certain extent, says a weed scientist with Agriculture and Agri-Food Canada’s science and technology branch at Lacombe.

However, Breanne Tidemann says it was a different story in parts of the province that received substantial amounts of precipitation in June, where weeds such as volunteer canola emerged after the herbicide application window had closed.

As was the case in the two neighbouring Prairie provinces, kochia was a serious concern in Alberta last season and will likely be so again in 2024, Tidemann says. Of particular concern is how the broadleaf weed appears to be spreading to areas where it wasn’t previously present.

“We really saw some movement of kochia more north last year. We actually had a few producers in this county that were starting to deal with kochia (last year) whereas when I moved here in 2014, I was told kochia doesn’t grow this far north,” she says.

Tidemann says producers who received a fair amount of rain just prior to harvest last year should now be on guard for overwintering weeds such as cleavers, shepherd’s purse and stinkweed.

“We’ve got a study on overwintering weeds and cleavers and they were going nuts with fall emergence because they were getting enough moisture to pop,” she says.

“Areas that have cleavers or have issues with any of those fall-emerging weeds might want to be making a really close (inspection) this spring to see what’s already up. Make sure you’re out there prior to seeding, because a pre-burnoff may be warranted.”

Another possible concern in parts of the province that received precipitation late last season could be volunteer crops such as winter wheat.

Tidemann also suggests growers keep an eye out for pigweeds. Though they aren’t yet a problem in Alberta, Palmer amaranth and waterhemp are present in several bordering states and can move easily via equipment and animal feed.

Two other weeds Tidemann suggests growers need to be aware of are pale smartweed and chickweed. Farmers in some areas are really struggling with smartweed, although Tidemann isn’t sure if that’s due to resistance developing or conditions being favourable for development. Chickweed is being found in increasing locations based on the province’s latest weed survey.

Wild oat continues to pose a significant challenge for growers, thanks in part to the fact it’s almost full-resistant to Group 1 and 2 herbicides.

Tidemann’s advice to producers is to get out in fields early and scout. This will allow them to see what weeds they might be dealing with this season and will help determine why they might be present.

She also recommends growers get resistance testing done if they suspect they might have a herbicide resistance issue in their fields.

“It’s not super expensive and it tells you what options you’ve got left or what options are more useable.”

Tidemann also cautions that herbicide carryover could be an issue in parts of the province that received little precipitation last summer. She adds that’s why it’s important for growers to keep detailed herbicide records, so they know what was applied from year to year and what their carryover risk is.

The post Into the weeds: 2024 in preview appeared first on Grainews.

Unfortunately, this also includes weed problems.

Weeds know no borders, of course, so when weed trouble or a resistance issue surfaces on the northern U.S. Plains, there’s a decent chance of it turning up somewhere on Canadian cropland sooner or later.

“Folks in Manitoba and Saskatchewan will often look south, and we also often look north for the problems our neighbours on the borders are experiencing, because it’s kind of a good indicator of what might be the next weed challenge problem,” says Joe Ikley, an extension weed specialist with North Dakota State University.

Grainews interviewed Ikley after he ventured north in February to speak to Canadian farmers attending the CropConnect 2024 conference in Winnipeg. He cautioned them about three particularly problematic weeds in North Dakota: kochia, waterhemp and Palmer amaranth.

Kochia

U.S. and Canadian crop producers alike have had to deal with kochia for many years. Ikley notes the pernicious tumbleweed has been tumbling around farms in the northern Great Plains states and on the Canadian Prairies for more than 100 years, and it is now found in every corner of North Dakota.

“Where it becomes a very big problem for us in modern row-crop production is herbicide resistance,” he says.

“This is one of the first weeds in North Dakota that was documented to develop resistance, really starting with the herbicide 2,4-D probably 40 or 50 years ago. Since then, new chemistries have come along, and there just seems to be a small lag between an introduction of a chemistry and some resistance being found in kochia if that chemical is used on a wide scale,” Ikley adds.

“For a new chemical introduction in small grains that might be used on eight million acres, for instance, it doesn’t take too long to find kochia resistance to that type of product.”

In North Dakota, there are kochia populations resistant to Groups 2, 4, 5 and 9 herbicides, and a new type of resistance has just turned up that spells trouble for crop producers.

That new issue, Group 14 resistance, is serious since two Group 14 herbicides, saflufenacil and carfentrazone, are frequently used by North Dakota farmers as a burndown tool on their no till acres.

“The group 14 resistance is new for us. 2021 to 2022 is when we first heard a lot of complaints about it and then confirmed this type of resistance,” Ikley says.

“This is very important … because we’ve relied on some of these products to control kochia,” he adds. “For decades we relied on glyphosate, and it was very effective ahead of planting crops, but with glyphosate resistance, that’s not an option.

“Now all of a sudden, (the Group 14 herbicides) are tools are out of our toolbox with these new resistant populations, which then leaves few effective herbicides we can use in that burndown or pre-seed type of application.”

In his home state, Ikley says, farmers have an easier time managing kochia in corn and small grains. “That’s because the herbicide chemistry in those crops has remained relatively effective on our kochia populations.”

He notes there are fewer control options in broadleaf crops, especially soybeans, in North Dakota.

“Soybeans are less competitive early in the season, and that’s where kochia can really thrive if we have resistance to soybean chemistry,” says Ikley. “Certainly, we can see up to 50 per cent yield loss in a soybean crop from a competitive kochia population.”

Waterhemp

Waterhemp is a type of pigweed first identified in North Dakota’s Red River Valley in the 1990s. Ikley says in the late 2000s and early 2010s, it started to become major problem in the southeastern part of the state.

“It’s now the dominant weed in that southeast corner,” he says. “It has spread and can now be found in basically every county in the eastern half of the state.”

Ikley notes waterhemp is showing up more frequently in three counties right next to the Canadian border, which is cause for concern for Manitoba farmers.

“Prior to 2023, we might find a handful of plants in some fields in those counties. This past year, we had a few fields with five- or 10-acre patches of very dense waterhemp infestations,” says Ikley.

Waterhemp was first detected in Manitoba in 2019 and is classified as a noxious weed requiring rigorous control measures. According to Manitoba Agriculture, there were 19 rural municipalities with fields where waterhemp was detected in 2023, most of them in the southeastern corner of the province.

Waterhemp in North Dakota is most problematic in sugar beets, soybean, and dry edible beans. “Those are some of our crops that have limited effective herbicide options and are relatively slow to grow and develop in the spring,” Ikley says.

Ikley notes he’s seen serious waterhemp infestations in soybean crops result in yield losses of up to 75 per cent.

One of the reasons for waterhemp’s spread in North Dakota is rising herbicide resistance. According to Ikley, you’ll find resistance to Groups 2 and 9 in pretty much every waterhemp population in the state, and there’s also Group 4 resistance farmers must contend with.

And just like their kochia counterparts, North Dakota’s waterhemp populations are also developing resistance to Group 14 herbicides.

Ikley says that’s a serious concern in soybean and dry beans, since the Group 14 herbicides are commonly used for both pre-emergence and post-emergence weed treatments in those crops.

Ikley maintains escapes of Group 14-resistant waterhemp from pre-emergence applications are a major concern for season-long weed management. Fortunately for North Dakota soybean producers, he says, they still have some post-emergence options for cleaning up these escapes.

Palmer amaranth

Palmer amaranth is another pigweed species that Ikley says was first detected in 2018 in North Dakota. Since then, it has been found in fields in 19 counties in the state.

The first case of Palmer amaranth in a Manitoba field was in 2021. As of the 2023 crop season, identification of the weed was limited to a single rural municipality, Dufferin.

According to the Manitoba Crop Alliance, neither waterhemp nor Palmer amaranth, which is also classified as a noxious weed in Manitoba, has yet been detected in Saskatchewan and Alberta.

Ikley says to date, Palmer amaranth infestations in North Dakota haven’t been as serious as they have been with waterhemp.

“We’re on high alert for infestations,” he says. “We’ve raised a lot of awareness on Palmer amaranth in hopes of finding infestations when they’re early and removing them, and that has been effective. … For the majority of infestations, I would say, we have been able to keep them under control.”

Ikley maintains the best way to stop the spread of waterhemp, as well as Palmer amaranth, is with pre-emergence or pre-seed herbicides. That’s because the weeds are so much more difficult to control once they’re out of the ground.

Like waterhemp, Palmer amaranth can evolve herbicide resistance quickly. In North Dakota, the resistance list for this weed now includes Groups 2, 4, 5, 9 and 27 herbicides.

Ikley has conducted research into the kinds of herbicides North Dakota farmers could still count on for Palmer amaranth protection across a broad range of crops. Glufosinate, a Group 10 herbicide, was one; the other, perhaps surprisingly, was Group 14 herbicides.

Prolific seed producers

Both Palmer amaranth and waterhemp can growly very quickly — up to two to three inches a day in optimal conditions -— and they’re also prolific seed producers, which enables them to quickly take over fields if the plants aren’t effectively controlled.

When there’s direct competition with crops, these weeds can produce up to 100,000 seeds per female plant. But that number swells to more than one million when there is no competition.

Palmer amaranth and waterhemp, like all pigweed species, have small seeds, which enable them to be easily transported to new areas through contaminated straw, hay and other animal feed.

Farm equipment like combines can also carry the weed seed a long way. Contaminated cover crop seed and migratory birds can contribute to the spread of Palmer amaranth and waterhemp as well.

The post Weed alerts on the southern front appeared first on Grainews.

If they don’t, they are making a “mistake,” he says.

“As a basic starting point, I think every grower should seed at least three varieties. Every year. As a minimum. Hopefully more than that,” says Bohner, the soybean specialist for the ministry of agriculture, food and rural affairs in Ontario.

Bohner spoke about soybeans, yields and management of the crop at the Manitoba Agronomists Conference, held last month at the University of Manitoba.

“Essentially, that (seeding more than one) is the difference between the guys… who are moving forward and the guys who call me up and say: ‘I’m frustrated with my soybean yield.’”

To support his argument, Bohner showed a bar graph 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 0.36 bushels is compared to soybean variety trials in Ontario, the data indicates 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 bushels,” he said.

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

“We don’t have exact numbers to tease that out. It’s a best estimate,” Bohner told the audience at a U of M lecture theatre.

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

But choosing the right variety could be the most important decision.

If a producer selects only one variety and grows it across the entire farm, how do they know it’s the optimal variety for their farm? For their soil and region?

“That’s what I’m trying to push against (planting one variety). I think that’s a big mistake,” Bohner said following his talk.

Planting three or four varieties doesn’t “guarantee more bushels,” he says — but it could add bushels and will help a grower understand what works on their farm.

“You will spread your risk. It doesn’t have to be 30 per cent – 30, 30 and 30,” he said. “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.”

Selecting the right genetics is crucial, but in recent years Ontario and Manitoba soybean growers have been changing some of their agronomic practices.

In many parts of Ontario, producers are moving away from no-till soybeans.

A big reason is huge corn yields.

If a farmer tries to plant soybeans following a 220-bushel corn crop, managing corn stalks becomes a massive challenge.

“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. That’s just the way it is,” Bohner says.

“Most, at least where I am in Perth County, have given up altogether on a true no-till. They’ve gone back to some form of incorporation. Whether it is a high-speed disc, or vertical tillage.”

Herbicide resistance

In Ontario and Manitoba, soybean growers have changed or will soon change their practices to control weeds.

For many years, producers relied solely on glyphosate to keep their 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, the soybean and pulse specialist with Manitoba Agriculture, who also spoke at the agronomists’ conference.

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

Herbicide-resistant strains of waterhemp have been seen in Ontario since 2002 and in the United States since 1993, making their way up into northern-tier states including Minnesota, Wisconsin, Michigan, North Dakota and, most recently, Idaho.

In Manitoba, Lange says, “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 may be resistant to multiple herbicides. It is designated as a Tier 1 noxious weed in Manitoba, so it must be destroyed when found.

Waterhemp can be managed, but soybean growers and other farmers need to adapt.

In 2023, some producers didn’t adapt, and ran into problems.

“What was very common this year from growers that did have issues with waterhemp… they were using Enlist soybeans or the Xtend soybeans,” Lange says.

Those products tolerate two or three types of herbicides. Enlist beans have tolerance for glyphosate, 2,4-D choline and also glufosinate. Xtend beans can tolerate glyphosate, dicamba and glufosinate.

“Instead of putting that application (a second herbicide) on early in the season, they just sprayed glyphosate,” Lange said. “Then, all of a sudden, they gave us a call (when) waterhemp plants were up to (their) knees… Glyphosate-only can run you into problems.”

The post Planting just one soybean variety is a ‘mistake’ appeared first on Grainews.

It will be a similar story in 2023. The difference this time around is that battle could be shaped largely by the location where it is being fought.

While Manitoba received significant moisture last season, many parts of Saskatchewan and Alberta remained dry and continue to deal with the effects of moisture deficits from the previous couple of seasons.

Grainews recently spoke with experts in the three Prairie provinces about the weed outlook for this year and what growers should know as they prepare for the coming season.

Manitoba

Kim Brown-Livingston, a provincial weeds specialist with Manitoba Agriculture, says a decent amount of rainfall last summer means fields in Manitoba are in pretty good shape heading into 2023. As far as weeds are concerned, it will be a relatively “normal” year, she explains.

“I think we’re getting closer to normal, like what we would expect to be seeing with normal conditions and needing those burnoffs and pre-emergent herbicides for residual weed control, and getting back into the habit of using those,” she says.

“A lot of that had dropped off the table because it was just so dry (previously) that we weren’t seeing enough weed growth to justify using those (herbicides).”

Brown-Livingston says two weeds that should be on everyone’s radar in Manitoba are waterhemp and Palmer amaranth. Both are relatively new threats in the province and are members of the pigweed family.

Waterhemp is like redroot pigweed “on steroids,” she says.

It’s much taller (up to eight feet tall), produces a lot more seeds and is a much more aggressive plant than most pigweeds. Brown-Livingston says it poses a great risk to row crops, in part because there is ample space for it to grow between rows before a canopy cover develops. There are also limited herbicide options for many row crops.

Further complicating things is the fact that waterhemp is believed to have come to the province from Eastern Canada or the northern United States pre-loaded with resistance to several herbicide groups including Groups 2 and 9.

“If this weed shows up and you were trying to spray it, you could have little or no success,” she says.

There haven’t been many reported cases of Palmer amaranth in Manitoba to date, but Brown-Livingston says growers must remain vigilant. It can grow to be even bigger than waterhemp, can be more aggressive and can develop resistance very quickly.

One of the problems with waterhemp and Palmer amaranth, Brown-Livingston notes, is by the time farmers notice it in their fields it’s often too late to spray, even if some herbicides could still control it.

The good news is that a strong, competitive crop can quickly cover the ground and prevent waterhemp and Palmer amaranth from getting a head start.

Any discussion about weeds would be incomplete without a mention of kochia. Brown-Livingston says the dry, salty soil in most of the province during the previous two years created ideal conditions for kochia.

Now that the province seems to be emerging from its latest dry cycle, she expects to see those saline areas shrink and more competitive crops grown. This could slow the spread of kochia in fields where it’s already present and prevent it from spreading into new areas.

Canada fleabane, also known as horseweed, has been around in Manitoba for some time, but it has never posed much of a problem — until recent reports of potential glyphosate resistance.

The threat it poses to crops such as soybeans and corn could now be much higher, Brown-Livingston explains.

“We haven’t seen it resistant like it is in Ontario and the United States. It has always been something we could control, so that (resistance) is something that’s brand new and needs to be on everybody’s radar,” she says.

Brown-Livingston also notes that farmers should be prepared for a return of perennial and winter annual weeds as the province appears to be entering a more normal or possibly wetter moisture cycle.

Saskatchewan

Clark Brenzil, a provincial weed control specialist with the Saskatchewan Ministry of Agriculture, says soil moisture shortages will likely continue in many parts of the province that went into last fall without soil moisture reserves, particularly on the western side of the province.

Despite the dry conditions, the weed threat will remain significant, Brenzil suggests. He says that could be particularly true with kochia, Russian thistle, green foxtail, lamb’s quarters, wild oats and pigweeds, which tend to be better adapted to hotter, drier conditions and “get up out of the ground quickly.”

“Generally, whatever weeds have been growing in your fields the last couple of years, they are likely the ones growing there this year,” he says.

Although waterhemp and Palmer amaranth aren’t a major concern in Saskatchewan yet, Brenzil says provincial officials are “keeping an eye out for them,” since they have been detected near the province’s borders to the east from Manitoba and to the south from North Dakota.

Brenzil says growers should take note of any pigweeds that pop up above crop canopies such as lentils and soybeans and appear to be significantly larger than normal after an in-crop weed control pass.

If farmers are concerned waterhemp or Palmer amaranth may be present in their fields, he suggests contacting an agronomist or one of the province’s regional specialists to investigate the site and collect weed samples for proper identification.

Alberta

Although the soil moisture situation in Alberta was better heading into 2023 than it was last year, there remains what has been called an “island of dryness” in areas around the city of Calgary including Airdrie and Red Deer.

Charles Geddes, a research scientist with Agriculture and Agri-Food Canada (AAFC) based in Lethbridge, says while it’s difficult to predict which weeds will be the most problematic during the upcoming growing season, kochia and Russian thistle are likely to remain a concern in southeastern areas of the province with drier soil.

Wild oats have been an issue in Alberta for some time and Geddes says it’s likely to be an issue again this year.

One of the newer weed threats in Alberta is glyphosate-resistant downy brome, which was first confirmed in southern Alberta in 2021.

Geddes says the province doesn’t yet know the extent of the problem and hasn’t been contacted by many farmers or agronomists who suspect they may be dealing with the weed.

“We’re hoping it’s a localized case and it won’t spread from there, but we haven’t done a survey yet to know how widespread the issue is,” he says, adding that downy brome is a problem mostly associated with winter crops such as winter wheat.

Although pigweeds, such as redroot, green and smooth pigweeds, have been present in Alberta for a while, newer species such as waterhemp and Palmer amaranth have yet to show up in the province. However, Geddes says there are concerns they could potentially arrive in Alberta as growing seasons become longer.

“It’s likely they’ll eventually make their way to Alberta, but it would be surprising if it did happen that quickly,” he says. “But we do know they’re on the Prairies and they’re likely spreading.”

Herbicide carry-over risk

While the weed threat will vary from region to region in 2023 in part because of soil moisture levels, the same holds true when it comes to herbicide carry-over, since herbicide breakdown is largely governed by a combination of moisture and warm temperatures.

Based on soil moisture maps for the 2022 growing season, while the majority of herbicide residue degradation would occur prior to spring 2023, Geddes says the southeast corner is the area of greatest concern for herbicide carry-over in Alberta.

However, he said precipitation can be highly variable from field to field and farmers should consider how much precipitation they received last year in comparison with an average year to determine their levels of risk.

Farmers should also review the re-cropping restrictions of any residual herbicides they used in 2022 and to check with manufacturers to determine if there have been any updates issued for the coming growing season.

Brown-Livingston says Manitoba is in “better shape than we have been in years” when it comes to the risk of herbicide carry-over, thanks to a return to more normal precipitation levels.

Still, she recommends farmers not take the situation for granted, especially if their fields are located in an area that received less-than-normal rainfall. She also suggests growers check label recommendations for any herbicides they used last year, which are also available in the province’s annual crop protection guide.

In Saskatchewan, the risk of herbicide carry-over is still relatively acute on the western side of the province, although not quite as severe as it was last year, Brenzil says.

The eastern side of the province is in good shape, he adds, since it received a significant amount of rainfall early last season.

His advice to growers who may be concerned about herbicide carry-over this season is to be conservative about their crop choices and go with longer rotation periods.

Brenzil also recommends growers be conscious of the quality of the water they mix with their herbicides this coming season. One of the results of last year’s glyphosate shortage was many farmers resorted to using reduced rates, which in combination with antagonism from water quality resulted in the product not working as expected.

He suggests farmers get their water sources tested early in the season to make sure they know the level of water hardness they are dealing with.

“You want to make sure you’re getting the most out of a product you (use),” he says.

Herbicide resistance

Herbicide resistance is on the minds of farmers, agronomists and researchers across the Prairies this season.

Herbicide-resistant weeds are estimated to cost western Canadian farmers as much as $530 million annually in lost yields and alternative weed management practices.

Numbers from Manitoba’s latest herbicide-resistant weed survey conducted in 2022 are expected to be released this fall. It will likely show that kochia remains one of the worst herbicide-resistant weed issues in the province.

Brown-Livingston says herbicide-resistant kochia is a widespread problem in Manitoba and the number of acres where it has been detected continues to grow.

“The resistance is increasing, and we need to be watching,” she says, adding herbicide resistance in wild oats continues to be an area of concern.

Another issue in Manitoba, according to Brown-Livingston, is weed resistance to the Group 9 herbicide glyphosate.

To tackle this problem, growers can tank mix other products with glyphosate whenever possible. Adding more complexity to herbicide mixtures can help slow the development of resistance. She also points out the most effective tool in slowing herbicide resistance is growing competitive crops.

In Alberta, there is concern about possible resistance to protoporphyrinogen oxidate (PPO) inhibitors, or Group 14 herbicides, in kochia.

Geddes says growers should watch for activity in their pre-plant burndowns if they’re using Group 14 products.

Indication of a problem is when kochia plants that have been hit with herbicide remain alive next to others that are dead. Geddes recommends farmers contact him about herbicide-resistant weeds because his lab is working to characterize the issue in the Prairies.

Another herbicide-resistant weed concern in Alberta, according to Geddes, is wild oat resistance to Group 1 and 2 herbicide products, which is a widespread and continuing issue for many farmers.

Brenzil says herbicide resistance has been on an upward trajectory in Western Canada since the 1990s and isn’t likely to change anytime soon unless producers make significant changes in how they manage their crops and their weeds.

In Saskatchewan, the most recent herbicide-resistant weed survey showed 87 per cent of kochia plants sampled appeared to be glyphosate resistant. High levels of dicamba and fluroxypyr resistance have also shown up in recent Alberta surveys, he adds.

“We’re closing doors one at a time to be able to control that weed,” he says.

A shift in thinking is needed about how kochia and other herbicide-resistant weeds are managed.

“Even though we have all of these new technologies that are making things easier for us, it’s also making things easier for some of these weeds to be more problematic in the system,” he explains.

“One of the things that we’ve done that has made life a little easier for kochia is that we’re always entertaining reducing our seeding rates (and) we’re always pushing our row spacing out rather than bringing it back in to the standard that has been around since time immemorial, which is six to eight inches for row spacing.”

The post Your provincial weed outlook for 2023 appeared first on Grainews.

Lucas farms near Starbuck, Man., growing corn, soybeans, wheat, oats and canola. I received a call from Lucas at the end of June last year. He suspected he had some herbicide efficacy problems, as he noticed some redroot pigweed was not dying after he sprayed a field of corn with Roundup.

“It’s been three weeks since I sprayed, and the weeds have only got larger. They should be dead and gone,” he said.

Upon arriving, I saw exactly what he meant. There were definitely some weeds that were not affected by Lucas’ previous herbicide applications.

Herbicide resistance was top of mind for me, considering the herbicides Lucas said he had sprayed should have killed the redroot pigweed we were both looking at. There were other weeds in the field that had clear herbicide damage. They were dying off — both grassy weeds and broadleaf weeds — while the pigweed remained.

I knew we had to eliminate all obvious potential causes right off the bat. Perhaps his sprayer malfunctioned and missed the pigweed? We quickly ruled this out, as there were other patches of redroot pigweed in the field his sprayer had definitely hit — they were not in straight lines like one might expect from a sprayer miss.

Perhaps he didn’t handle the chemical properly? Nope. It turned out the chemical was well mixed and spray booms were charged before spray application began.

What about dust from the nearby road, I wondered? Road dust can often reduce herbicide efficacy. However, it wasn’t that either. Regular rainfall and calcium-based dust control had been applied before Lucas sprayed his field. Something else was at work here.

I asked Lucas about the history of this particular field that perhaps made it unique from the others. Currently, he had corn planted and he’d sprayed Roundup. In 2020, he grew soybeans and sprayed roundup. The year prior, in 2019, he grew oats and sprayed Refine SG, he said.

He had been spraying Group 2 and 9 chemistry over the past three years. Resistance could very well be the culprit, but the herbicides he had been using should have killed the redroot pigweed, which hasn’t been known to develop resistance to those herbicides. Something didn’t make sense.

It was time to do some tissue testing to see what was going on here.

Crop advisor solution: Weed misidentification, herbicide resistance lead to trouble

I took some tissue samples, and when the results came back, my suspicions were confirmed. The pigweed wasn’t pigweed at all. It was waterhemp. When I told Lucas, everything fell into place.

The field is close to large drainage ditches where water can back up onto the field during spring melt or during times of very heavy rainfall events. Waterhemp moves in bodies of water and could have travelled up the waterways and eventually deposited seeds on this field.

Waterhemp is notorious for developing Group 2 and 9 herbicide resistance, and the crop rotation Lucas used created the perfect conditions for this to happen.

Unfortunately, his yield was affected, as the weed seedbank in the field bolstered.

Lucas has committed to changing up his crop and herbicide rotation and to use tools that are effective in controlling waterhemp. Other possible herbicides that could be used, depending on the crop, to reduce waterhemp in the field include pyroxysulfone, dicamba and sulfentrazone.

Thankfully, using these other modes of action, Lucas found he had better weed control and was able to continue growing crops that diversified his rotation.

I encouraged him to properly identify weeds as early as possible in the future and control them in a timely manner using different chemical modes of action. This would be a recipe for success and should prevent further issues with waterhemp.

The post Crop advisor casebook: Why is this Manitoba field full of pigweed? appeared first on Grainews.

Quebec’s Reseau d’avertissement phytosanitaire (RAP) last Friday reported a patch of waterhemp with resistance to mesotrione herbicide in the Haut-Richelieu municipality, in the province’s Monteregie.

A Group 27 HPPD enzyme inhibitor, mesotrione is the active ingredient in Syngenta’s Callisto herbicide and one of several in products such as Halex and Acuron, all used mainly for broadleaf weed control in corn crops.

Tests by the Centre de recherche sur les grains (CEROM) also confirmed resistance to Groups 2, 5 and 9 (atrazine, metribuzine and glyphosate respectively) in the same waterhemp patch, RAP reported.

Established in Ontario since 2002, Manitoba since 2016 and Quebec since 2017, having arrived via the central and eastern U.S., waterhemp is able to germinate all throughout a growing season.

The weed is also known to be highly prolific — a single plant can produce up to 300,000 seeds — and if left unchecked, has been known to cause yield losses of up to 73 per cent in infested corn and soy crops, RAP said.

The plant also grows rapidly, at a rate of up to 2.5 to three centimetres per day, and is tough to distinguish visually from relatives such as redroot and green pigweed.

Waterhemp patches in Ontario have previously shown resistance to groups 2, 5 and 9 and, more recently, Group 14. That group includes PPO inhibitors such as Syngenta’s Reflex and Corteva’s Goal, also used mainly for broadleaf weed control.

The Quebec agriculture ministry previously set up a support program to help corn and soy growers deal with waterhemp infestations. RAP, in its notice last Friday, urged affected producers to sign up for the program, to help limit the weed’s further spread in the province. — Glacier FarmMedia Network

The post Group 27 herbicide resistance arrives in Canada appeared first on Grainews.

And, as reported by Canola Council of Canada (CCC), Palmer amaranth, another aggressive pigweed with populations resistant to many herbicides, is moving north from North Dakota toward Manitoba and Saskatchewan as well.

Each waterhemp plant can produce up to 200,000 very small seeds, which can be spread by contaminated equipment, waterfowl and more. Like Palmer amaranth, waterhemp is present in both North Dakota and Ontario. As reported late last fall, researchers have found waterhemp populations in two areas of Ontario with resistance to glyphosate, independent of resistant populations in the United States.

Clark Brenzil, a provincial weed control specialist with Saskatchewan Agriculture, has heard rumours that waterhemp is present in a couple of counties in North Dakota just south of the border between Saskatchewan and Manitoba. He will be looking for it in southeastern Saskatchewan this coming summer and encourages any producers who think they have it (it’s similar to a pigweed with narrow leaves) to contact him by email (clark.brenzil@gov.sk.ca) or phone (306-787-4673).

Under Manitoba’s Noxious Weeds Act, waterhemp and Palmer amaranth are categorized as Tier 1 Noxious and must be destroyed — but should be tested for resistance first. Farmers can be fined if they do not comply with notices to destroy it, and any equipment that’s been in a field containing waterhemp must be thoroughly cleaned. Contact Jones by email (tammy.jones2@gov.mb.ca) or phone (204-750-1235) to report the presence of waterhemp. She can help arrange for herbicide resistance testing using green leaf material as well as a weed destruction plan.

“There are seven modes of action that this weed is resistant to, and resistance to Group 2 and 9 are so far confirmed by PCR testing in Manitoba,” says Jones. “We really need to be proactive this year with surveillance and do a lot of testing to optimize management. It costs about $200 to test 10 plants from a field. Compared to the cost of the herbicide and of spraying it — and the impact of the weed growing out of control because the herbicide doesn’t work anyway — $200 is a good investment.”

Alberta is at low risk for waterhemp to get a foothold, says Chris Neeser, a weed research scientist at Alberta Agriculture and Forestry, because it doesn’t do as well in the cool nighttime temperatures of the western Prairies. However, it may arrive in future.

There are two other weed species on Jones’ radar. “Woolly cupgrass in North Dakota also may be a threat in the future,” she says. “I keep expecting resistant Canada fleabane to take off in Manitoba but it doesn’t seem to be happening as it has in Ontario. I’d be very happy to have it stay that way.”

Herbicide-resistant kochia

Kochia is another weed found across the Prairies that has resistance mostly to Group 2 herbicides and with some resistance to Group 4. There has also been a sharp increase in resistance to Group 9.

Jones believes this is the tip of the iceberg. “A lot of farmers are using glyphosate and in many populations it will now control 80 per cent of kochia, but in two years, with continued reliance on glyphosate alone, it will not be effective at all,” she says. “Kochia has a short seed life of one to three years and we should be able to get rid of it, but it’s more resilient and adaptable than I had thought.” She reports that growers can get a green leaf material test for glyphosate resistance through the Pest Surveillance Initiative (mbpestlab.ca) with results in one to two weeks, however, seed testing takes longer.

In terms of spread, CCC reports in Canola Watch that kochia produces 15,000 to 25,000 seeds per plant, and mature weeds, once they break from their stems and start to tumble with the wind, can spread these seeds over a fairly wide area. In addition, kochia often takes over saline or other marginal areas. Farmers should consider seeding kochia-infested areas to salt-tolerant perennial forage rather than continue to throw inputs at it, the publication states.

In Alberta, Neeser reports normal and glyphosate-resistant kochia is present south of Highway 1 and north of it up to Red Deer county. “Use rotation and other integrated weed control practices as much as possible in addition to alternative herbicide options,” he says.

Alberta growers who wish to test for kochia they suspect may be glyphosate-resistant should contact Charles Geddes, lead investigator in weed ecology and cropping systems at Agriculture and Agri-Food Canada’s Prairie Herbicide Resistance Research Lab in Lethbridge (403-359-6967 or Charles.Geddes@canada.ca). Geddes can direct farmers to the appropriate lab. His lab also tests other weeds for glyphosate resistance and carries out tests for dicamba/fluroxypyr resistance.

The post Watch for expansion of waterhemp, Palmer amaranth and kochia in 2020 appeared first on Grainews.

The province might be losing the war on herbicide resistant weeds; reports from the U.S. say despite some kind of trade deal with China, U.S. farmers figure they will need more than a $25 billion bailout in 2020 — (yes, that’s correct, more than $25 billion); and swine fever continues to spread through Poland, heading for Germany. I quit reading after that.

It must have been that late January blues that attracted me to those items. I know there are plenty of good things happening in agriculture, but those headlines seemed to gang up on my psyche.

I’ve often wondered about the war on weeds. There are plenty of great herbicides promising to be the solution to some of the most complex weed spectrum problems, and yet I don’t believe I’ve ever heard any farmer say, “thanks to herbicides we are seeing a lot less weeds in our fields.” (If that’s happening on your farm please let me know.)

In the Co-operator article written by editor Gord Gilmour, he talks to Tammy Jones, provincial weed specialist, about what she’s seeing out there. And it’s not all that pretty. With certain weeds, Mother Nature plays a tremendous numbers game.

Manitoba is dealing with a couple of new weeds that could become a threat for all Western provinces. As the Canola Council of Canada points out: “Tall waterhemp is confirmed in eastern Manitoba. Palmer amaranth is in North Dakota and moving north toward Manitoba and Saskatchewan. Both are big aggressive weeds with populations resistant to many herbicides, including glyphosate. If you find them, destroy them immediately.”

Jones is repeating that no nonsense message. Last summer she spent a few hours in a Manitoba field yanking about 300 well-rooted waterhemp plants from the ground and carrying them to the edge of the field to be destroyed. She estimates that effort removed about 90 million herbicide-resistant waterhemp seeds from the environment, helping to reduce the spread of one of the most aggressive weeds on the landscape.

She says that’s the type of vigilance farmers need to apply. If they see a small patch of weeds, whether it be this new waterhemp, or any other patch of weeds that seems to have survived a herbicide application, stop, get out, hand pull the weeds, remove them from the field and make sure they are destroyed.

Jones says it can cost money to apply proper control measures to remove waterhemp plants, but the alternative of doing nothing isn’t really an option. A waterhemp infestation can reduce soybean yields by 40 to 95 per cent.

And here’s where the numbers really mount up. One Manitoba farmer last year had a 35-acre patch of waterhemp weeds, resulting in zero crop yield over those acres. Not only did he lose about $9,000 worth of inputs spent to seed the crop on those acres, he then had to pull out all the stops to eradicate that large weed patch. With tillage and/or mowing and other measures, total cost of those weeds came to about $15,000.

Jones says it seems like a lot of money, but on the other hand that 35-acre weed patch had the potential of producing about 305 billion seeds. Even if normal control measures had eliminated 99 per cent of those weed seeds, that would have left a potential 300 million waterhemp plants. As Jones says, how can you grow any crop if you already have 300 million yield robbing seeds just waiting to take over?

It may seem like a losing battle, but researchers aren’t giving up. In Alberta, Breanne Tidemann, a weed scientist with Agriculture Canada in Lacombe, is urging Canadian farmers to consider some weed control measures that have been developed by Australian farmers. Chaff burning, chaff collection and removal, feeding chaff to livestock and installing weed-seed crushers on combines are some of the ideas being put forward. These measures aren’t necessarily winning the war on weeds, but they are helping farmers hold their ground on the battlefield.

The post War on weeds, take no prisoners appeared first on Grainews.