Canola School: Putting Group 14 resistant kochia on the radar, with suspected cases in Saskatchewan and North Dakota

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Farmers in Western Canada should add another chemistry to the list to pay attention to when it comes to herbicide resistance in kochia, says a weed scientist with Agriculture and Agri-Food Canada.

The problematic weed is already known to be resistant to Group 2, Group 4 and/or Group 9 herbicides.

“The new thing that we’re working on is PPO inhibitor resistance, which is Group 14 resistant kochia,” explains Charles Geddes in this Canola School episode, filmed at CropConnect at Winnipeg, Manitoba last week. “Currently, in the Canadian Prairies anyway, we’ve found one population of kochia that appears to be Group 14 resistant.”

The plants in question were submitted from Saskatchewan in 2021. Initial screening using different doses of herbicide showed resistance to a Group 14 — saflufenacil, specifically, but Geddes says official confirmation is still pending results of testing that’s underway on whether the resistance trait is transferred from one generation to the next.

The findings are in line with a report from North Dakota State University in December 2022 that four kochia populations from across western North Dakota showed resistance to two Group 14 active ingredients — saflufenacil and carfentrazone.

“It’s looking, at least at this point, like [the Saskatchewan case] is quite likely the same thing,” says Geddes, noting the Canadian researchers working on this case are in close communication with their counterparts at NDSU.

Resistance to Group 14 herbicides is a concern, but it would not be a complete surprise, he notes, as many farmers have responded to challenges with glyphosate resistance in kochia by adding a Group 14 to their pre-plant burndown, increasing the selection pressure.

He’s urging growers and agronomists to pay close attention to how kochia responds to herbicide treatment this spring.

“I think it’s important, first of all, to get the message out there that this type of resistance is present on the Prairies, or it’s looking like it is present on the Prairies. So keep an eye out for it. If you’re mixing in a Group 14 for your pre planned burndown, for example, keep a close eye on on the control that you’re getting. And if you suspect that there might be resistance, please, please take a sample of that population and submit it to a lab for diagnostic testing,” stresses Geddes.

Watch this Canola School video, filmed at CropConnect, for more on the suspected case of Group 14 resistant kochia in Saskatchewan with Charles Geddes:

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