Concerns over a stacked-resistance superweed have not materialized in the years since canola variety became available
There’s a recurring fear that genetically modified crops stacked with herbicide resistance will escape and become unkillable superweeds.
Those questions arose again with the 2021 release of Dekalb’s Truflex DKTFLL 22 CRSC, a hybrid that features both Roundup Ready and LibertyLink technologies.
Shaun Sharpe, an Agriculture Canada weed specialist in Saskatoon, said he’s not surprised by the concern.
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“Canola is an important part of a crop rotation, so if we introduce any new traits, especially when they’re stacked, volunteer populations are going to be a concern. I can see the logic, but I think our growers are very adaptable, and they’re going to be able to manage this new challenge.”
That’s also what people at Bayer, makers of Truflex, are saying.
“Volunteer canola can be a very emotional weed for guys,” said Tim Darragh, Bayer’s technical strategy lead for canola. “When you don’t get the volunteer canola under control, it stands up big; you get those yellow flowers; your neighbours can see it. That’s where the issue comes from. Growers are really concerned about how to manage it.”
Darragh said it’s a common misconception that stacking traits will make that weed more resilient than normal canola. But Bayer’s research suggests it shouldn’t change the way farmers manage any volunteer canola or herbicide-resistant weed.
When it comes to pre-burn, the tank mixture is the key.
“When you’re managing a Truflex volunteer, you’re doing the right thing by throwing that second mode of action in the tank,” said Darragh. “By having that tank mix partner on that pre-burn, guys are doing what is needed to manage volunteers as well as herbicide resistance.”
His advice is to keep it simple.
“It’s your 2,4-Ds, your MCPAs, your bromoxynils, that are really cheap and easy to use.”
In-crop management is even simpler. There are many broadleaf products already familiar to growers that are capable of managing volunteers.
Darragh said growers’ fears when any new product becomes available tend to evaporate if the product delivers, as Truflex does.
“It had better pod shatter integrity; it had club root resistance; it had fantastic yield. It was a really good product, so it became more popular and more widespread,” he said. “Once growers began to understand how easily the volunteers could be managed, they adopted it, they stuck with it, and they kept growing it.”
That’s not the end of the argument. While it may be easy for farmers to manage, there is still concern about genetically altered crops becoming feral and passing herbicide-resistant genes to other volunteers.
Sharpe said he hasn’t heard it is a serious issue.
“I can’t really think of any cases off the top of my head, although I’m sure there are probably case studies of that,” he said.
There are. In 2021, a global review of academic literature looked at the unintended release of genetically modified canola (rapeseed). The results were published in the journal Biology.
The report concluded that, despite numerous recorded instances of unintentional releases, there had been no reports of “serious detrimental consequences.”
The report also said unintentional releases eventually do become feral weed populations and it recommended monitoring those populations.
