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Dealing with volunteer canola
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Dealing with volunteer canola

Apr 16, 2021

“One of the big misconceptions out there is that all volunteer canola is Roundup Ready®, but it’s not,” says Chris Hansen, a market development representative with Bayer in Carseland, Alberta.

In fact, says Hansen, LibertyLink® hybrids account for the largest canola acreage grown in Canada, followed by Roundup Ready hybrids, with Clearfield® pulling up third with less than three percent of acres seeded to the yellow crop. There are other players in the market, too, but it helps to know the rough division of acres when you’re facing a volunteer canola problem.

“Any of the canola systems can volunteer, just like any crop can volunteer,” says Hansen. “But canola tends to be a harsher problem because the seeds are so small.” They also contain herbicide tolerant traits that make control a bit more of a thoughtful exercise than with other crop volunteers.

So what’s the best approach for dealing with volunteer canola? Hansen has some suggestions.


Seed management

“Step one is keeping the seed off the ground,” he says. “That’s probably the number one volunteer control method.”

Hansen says there are two areas to focus on: combine calibration and pod integrity.

The Canola Council of Canada (CCC) says growers can lose up to 5 bu./ac. off the combine during harvest. Most losses occur as those little seeds bounce away going into and coming out of the combine. The CCC has some excellent tips to reduce combine losses to a minimum.

But even before the crop is harvested, Hansen says there is another way to reduce seed loss. “Look for hybrids with a pod shatter trait,” he says. Whether you straight cut or swath, a good wind event can leave a lot of seeds on the ground as brittle, maturing pods shatter.

He recognizes this isn’t always a straightforward decision. “Some hybrids are known for shelling out a bit, but if they do there’s usually a trade-off benefit elsewhere,” he says.

Post-harvest control

“A post-harvest herbicide application, or some kind of shallow tillage is useful,” says Hansen. “Try to work those volunteers in the fall – if they germinate while it’s still warm, they’ll frost off later.”

Tank mix your herbicides

Of course, herbicides are the key tool when it comes to controlling canola volunteers. But the incidence of herbicide resistance grows, and as pretty much every volunteer canola plant carries a herbicide tolerance trait of some description, how and when you use herbicides is more important than ever.

“You can’t just spray glyphosate and be done with it,” says Hansen. Tank mixing herbicides is key to reducing the incidence of herbicide resistant weeds, including glyphosate-resistant canola volunteers. He says Bayer’s Mix-It-Up site has a pile of great information about herbicide and weed management strategies that can help.

Pre-seed herbicides

“A pre-seed burn is your biggest opportunity to control volunteer canola,” says Hansen. “A rule of thumb is: try to tank mix when you can, don’t just go with glyphosate alone.”

Timing, he says, is key. “Follow proper label directions and application timing guidelines to maximize herbicide performance.” Hansen urges growers to think beyond volunteer canola – what other weeds need to be controlled in the field and build your spray plan, accordingly, matching your herbicide to your most difficult weeds.

Rotate crops, not systems

“Rotating canola systems is kind of a band aid solution to control volunteers,” says Hansen. The idea seems sound – glyphosate will take out glufosinate-resistant volunteers and vice versa – but it’s not.

“If farmers have been growing both of the major trait systems, they’ve got volunteers of both in their field,” he says. “Looking at good agronomics is a better step than wearing out your farm. Canola-wheat-canola-wheat, even if you’re switching canola systems, is not good.”

He suggests a canola-cereal-pulse-cereal rotation to break weed cycles. Switching cereals between wheat and barley, or including oats or rye if you can is also a good idea. And Hansen says the pulse portion of that rotation could mean soybeans or corn if you’re in an area where those grow well.

A pat on the back

As challenging as it can be sometimes to get control of volunteer canola, Hansen thinks most farmers are doing a good job. “As much as you see guys complaining about volunteers, they’re generally managing them well,” he says. “They know what they need to do even though they might not always be able to do it.”

“Volunteer canola is an issue and we can’t pretend it’s not,” says Hansen. “Unless canola hasn’t been grown on a field for years, it’s going to be there.”

He’s confident, though, that as long as farmers continue to stay on top of the issue, volunteer canola can be successfully managed.


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