“I think the best management practice that someone could do for weed resistance is the one you’re not currently doing on your farm,” said Rory Cranston, technical strategy lead with Bayer. “Weeds figure out habits. They don’t figure out different system approaches.”

Cranston spoke on a panel about herbicide-resistant weed management at the Bayer Crop Science booth during July’s Ag in Motion show in Langham, Sask.

Shaun Sharpe, a weed ecology research scientist with Agriculture Canada who was also on the panel, said afterward that using novel approaches to weed management doesn’t mean throwing the baby out with the bath water.

He says chemical control is the backbone of weed management strategies but the backbone is breaking. Farmers will have to adapt.

In conventional terms, spraying is timed to optimize yield, which seems like sound logic. The problem is that weeds that emerge later are often ignored because they don’t affect yield.

“Conventionally, we’ve just been leaving those alone. But, of course, those weeds produce seeds that go back into the seed bank,” said Sharpe. “Something like wild oat that emerges later has more potential to grow and produce seeds later in the season.”

The pillars of any weed management strategy are chemical control (herbicides), cultural control (crop rotation, cover crops), mechanical control (mowing, hand weeding) and, to a lesser extent, biological control.

Sharpe said farmers should focus on cultural strategies to reduce weed populations.

“We want to get canopy closure quickly, and we want to have a very competitive crop. So we want to pick crops that are going to be competitive against weeds, and we want to plant them in a way that we’re going to get good canopy coverage quickly.”

Those strategies could include higher seeding rates, using cover crops or introducing intercropping.

While none of these techniques are new, Sharpe said there is more interest in intercropping as a weed control method.

“When I was at AIM, I spent a lot of time at the intercropping plots for AAFC. I found that there is a lot of good feedback from the growers. They’re interested in how you seed it, how you harvest it, whether you can spray anything in it, and how it does against disease and weeds.”

Agriculture Canada is focusing on intercrop­ping as a management strategy to combat herbicide resistance.

“I think that that system is going to grow. It’s just going to take some time, because it’s a new way to farm for a lot of folks who are doing monocultures,” Sharpe said.

“There’s still a lot of agronomic questions to answer, but I think it does have a lot of potential, and there was definitely a lot of interest from farmers.”

He said one thing is certain. No one is under the illusion that herbicide chemistries will be the saviour of agriculture as they once were.

“With herbicide resistance, we’re not going to spray our way out of it. That’s been the message for a few years now.”

Emerging technologies are helping farmers be more efficient with spraying. Targeted use of chemicals can extend their effectiveness and prevent emergence of herbicide resistance.

Optical spot sprayers are one tool in the fight. Boom-mounted cameras can detect a weed and spray it. The sprayers have been around for a while and the technology has recently been adapted for spray drones.

One company is taking the precision spraying concept beyond the seek-and-destroy approach of optical spot sprayers. Geco Agriculture’s predictive weed control system promises to pinpoint the location of weeds before they emerge.

It will even predict patches of herbicide-resistant weeds and it’s relatively inexpensive.

“They don’t need any new equipment, and they don’t need to adopt any new practices on the farm,” said Geco Agriculture CEO and founder Greg Stewart. “Really, what they’re buying from us is the analysis.”

The company pulls farm data (crop rotations, spraying records, etc.) from the past five years and sources imagery data from satellite providers.

In recent years, LiDAR (light detection and radar) and NDVI (normalized difference vegetative index) technology have exploded in terms of accuracy and scope, and they’re having a massive impact on agriculture.

But despite the resolution these satellite images can provide, it’s the scope rather than individual images that interests Stewart.

“What we really do is take a step back and try to understand how the weed population is evolving dynamically over several months and then over several years,” he said.

“You can get somewhere between two and four satellite images per week, depending a bit on cloud cover. We’re actually trying to leverage all of that data.”

With crop and spraying data collected from the farm, combined with the satellite data, Geco runs an analysis that produces several tools to manage weed pressure.

The first one is a five-year history of weeds in the field. An analysis produced today would go back to 2019 and indicate what weed patches looked like in each of those years, whether they’re getting better or worse, and the crops in which they appeared.

The next tool is a map that shows areas of potential herbicide-resistant weed patches in the field.

Stewart said farmers can use this as a preliminary indicator of potential resistance areas before the patches reach the size at which humans typically detect them.

The third tool is a prediction model, which estimates where the weeds will be in the coming season. The predictions aren’t infallible, but Geco has been conducting tests at a research farm run by the Winnipeg-based agricultural tech accelerator EMILI (Enterprise Machine Intelligence and Learning Initiative), and their predictions are close to the mark.

“Last year, we made predictions for 2024. We were usually in around the 90 per cent hit rate using the prediction,” said Stewart.

The final tool is a prescription map.

“The prescription map is just a file that a farmer will typically upload into their sprayer or granular applicator,” said Stewart.

“They’ll use the map to direct these actions towards the weediest hotspots, which will allow them to beat down the weeds before the season comes on.”

Ability to spray more efficiently will lower input costs.

“All of a sudden, it makes that more economically digestible to a farm and they may be willing to incorporate that into the rest of their weed protection program. So, you get an affordable way of introducing this mode of action into your strategy, and you get to focus it on where the weeds are the worst.”

Over time, “mother patches” of weeds reveal themselves.

“These mother patches of weeds that are out there tend to be your worst actors, and they will tend to donate weed seeds to the rest of the field. So, if you are able to start suppressing them, you can suppress weed emergence more generally, throughout the field,” Stewart said.

That’s just the chemical side of things. Geco’s predictive weed control system can also contribute on the cultural side of weed management.

“We’re getting people who are inputting our prescriptions into a seed drill,” said Stewart. “So what they’ll do is up the rate of seeding into the areas that are predicted to be the weediest, and that gives you some crop competition to fight the weeds. It’s just another tool in the toolbox.”

That was the takeaway from a panel discussion on managing herbicide resistance at this year’s Ag in Motion farm show.

“I think the best management practice that someone could do for weed resistance is the one you’re not currently doing on your farm,” said Rory Cranston, technical strategy lead with the panel’s host, Bayer Crop Science. “Adding in something different … Weeds figure out habits. They don’t figure out different system approaches.”

It was that philosophy that led Corey Loessin, who is fighting a stubborn kochia problem near Radisson, Sask., to get an old 8800 Bourgault cultivator.

“I’m a strong no-till supporter; I have been for 30 years, and so it hurt me a little bit to have to go and buy a cultivator,” he said. “But the idea is that we’re going to go early in the spring and try to cultivate some of these tiny kochia patches when the kochia is really small. And I don’t know if it’s going to work or how well it’s going to work, but I have to try something else, because if we keep doing what we’re doing, we’re going to end up with no control.”

Shaun Sharpe, a weed ecology research scientist with Agriculture and Agri-Food Canada, said dealing with a weed like kochia should be a community effort.

“One thing that we can do today that will affect the future is to work together,” he said. “Kochia is everybody’s problem. It’s going to tumble in the wind. It’s going to move across boundaries. It’s not going to care. It’s just going to keep moving.

“It’s not just in the agricultural fields. It’s on the roads. It’s on the oil wells. It’s on the railways. It’s from the cities. It’s everywhere. So, we’re going to need a community approach to really get things under control and it’s going to have to be very diversified as well.”

Chris Mansiere, field solutions agronomist with Bayer, added that producers cannot wait until the problem is obvious.

“If you stop being reactive and start being more proactive, I think you’re going to see a lot better results. Then you’re going to be able to use modes of action that you have a lot longer and, then, eventually there’ll be new modes of action. If you can keep the tools in your tool belt that you have right now, you’re going to have a lot more success in the future.”

Cranston urged farmers to think about their long-term return on investment along with their short-term bottom line.

“I think people balk at the price of innovation, but an ounce of prevention is worth a pound of cure,” he said.

“We have to do a couple of things,” Loessin argued. “One is to broaden our view of what we’re doing and the other is to start to employ some radical ideas, even if they’re old ideas.”

That was the takeaway from a panel discussion on managing herbicide resistance at this year’s Ag in Motion farm show.

“I think the best management practice that someone could do for weed resistance is the one you’re not currently doing on your farm,” said Rory Cranston, technical strategy lead with the panel’s host, Bayer Crop Science. “Adding in something different … Weeds figure out habits. They don’t figure out different system approaches.”

It was that philosophy that led Corey Loessin, who is fighting a stubborn kochia problem near Radisson, Sask., to get an old 8800 Bourgault cultivator.

“I’m a strong no-till supporter; I have been for 30 years, and so it hurt me a little bit to have to go and buy a cultivator,” he said. “But the idea is that we’re going to go early in the spring and try to cultivate some of these tiny kochia patches when the kochia is really small. And I don’t know if it’s going to work or how well it’s going to work, but I have to try something else, because if we keep doing what we’re doing, we’re going to end up with no control.”

Shaun Sharpe, a weed ecology research scientist with Agriculture and Agri-Food Canada, said dealing with a weed like kochia should be a community effort.

“One thing that we can do today that will affect the future is to work together,” he said. “Kochia is everybody’s problem. It’s going to tumble in the wind. It’s going to move across boundaries. It’s not going to care. It’s just going to keep moving.

“It’s not just in the agricultural fields. It’s on the roads. It’s on the oil wells. It’s on the railways. It’s from the cities. It’s everywhere. So, we’re going to need a community approach to really get things under control and it’s going to have to be very diversified as well.”

Chris Mansiere, field solutions agronomist with Bayer, added that producers cannot wait until the problem is obvious.

“If you stop being reactive and start being more proactive, I think you’re going to see a lot better results. Then you’re going to be able to use modes of action that you have a lot longer and, then, eventually there’ll be new modes of action. If you can keep the tools in your tool belt that you have right now, you’re going to have a lot more success in the future.”

Cranston urged farmers to think about their long-term return on investment along with their short-term bottom line.

“I think people balk at the price of innovation, but an ounce of prevention is worth a pound of cure,” he said.

“We have to do a couple of things,” Loessin argued. “One is to broaden our view of what we’re doing and the other is to start to employ some radical ideas, even if they’re old ideas.”

Shaun Sharpe, an Agriculture Canada scientist in Saskatoon, may have discovered another use for liquid smoke, which has nothing to do with sauces or smoked meat.

He thinks it could be used to control wild oats, a pesky weed on the Prairies.

The weed scientist is studying the idea of convincing wild oat seeds to germinate in the fall rather than during the growing season.

“With wild oats, they have a particular type of dormancy. It’s called endo-dormancy. It’s an internal control that prevents it from immediately germinating,” Sharpe said from his office in Saskatoon.

He wanted to know if he could overcome that endodormancy by spraying liquid smoke on wild oat seeds to encourage germination.

The concept is based on the principle that wildfire smoke can stimulate plant growth.

“Although it is still being studied, researchers believe it may provide a ‘scorched earth’ survival signal, as seen through the rapid regrowth of plant communities following a fire,” says an Agriculture Canada document explaining Sharpe’s research project.

“The idea is to stimulate seeds to grow at the ‘wrong’ time of year and then die off, which would drive down their density in the seedbed over time.”

Instead of actual smoke, Sharpe was curious if liquid smoke could cause weed seeds to germinate.

Liquid smoke, also known as pyroligneous acid or wood vinegar, is a byproduct of biochar production.

“(That) occurs when a biomass is heated in an airless container during charcoal/biochar production,” says the website woodvinegar.org.

“The exhaust smoke from this charcoal production is condensed (cooled) into a liquid.”

To test the concept, Sharpe conducted lab experiments in which wild oat seeds were placed on soil or in soil.

Then, the soil and seeds were placed in a cabinet sprayer, which is a chamber used to apply pesticides in a lab.

Within that cabinet, Sharpe and his colleagues applied a mixture of liquid smoke and water to the wild oat seeds.

The result? About 10 per cent more seeds broke dormancy, compared to a control group that didn’t receive the liquid smoke.

“It’s still very exploratory at this point, (but) it does seem to be active and it does seem to stimulate emergence of wild oats,” Sharpe said, adding this tactic could force the wild oats to germinate in the fall, and then the emerging weeds would die over the winter.

As a result, fewer wild oat seeds would be around the following spring.

“Can we take pressure off the in-crop herbicides by being able to stimulate them (the weeds) out the soil at pre-seed or post harvest time?”

The full results from Sharpe’s study were published in 2023 and can be found at cdnsciencepub.com/doi/10.1139/cjps-2022-0202.

A 10 per cent increase isn’t a lot, but it does suggest that the concept can work, at least in a lab.

Sharpe plans to test liquid smoke and its ability to stimulate seed germination in the field in the near future.

Before he moves forward, Sharpe will need approval from the Pest Management Regulatory Agency.

Still, he believes the idea has merit.

Wild oat seeds can lay dormant in the soil for three to five years or even longer. Any practice that reduces the number of seeds in the soil is a win for growers because it’s becoming more difficult to kill wild oats with herbicides.

A 2020 paper from Hugh Beckie, a former Agriculture Canada weed scientist, found that 62 per cent of wild oats on the Prairies are resistant to Group 1 herbicides and 34 per cent are resistant to Group 2 herbicides.

The percentage of wild oats with resistance could be significantly higher in 2024.

So, cutting the amount of wild oat seeds in the soil seedbank is a good thing.

“This is a tactic to try and slow down herbicide resistance,” Sharpe said.

“To try to tackle it in a new way.”