Glyphosate-resistant kochia has started showing up in more of Western Canada, and as with other cases of resistance, it’s becoming evident you can’t rely on a single tool for too long. Minimizing resistant weed populations requires an integrated or diverse approach.
The crop itself must help make survival difficult for potentially resistant weed seedlings, explains Rob Gulden of the University of Manitoba in this Canola School episode.
Kochia’s gene amplification method for becoming resistant to glyphosate is interesting, he notes, as the offspring from a resistant plant can range from completely susceptible to highly resistant.
A competitive crop that closes its canopy over the injured kochia seedlings will significantly reduce the odds of the resistant offspring surviving.
“On the other hand, if we have a crop with wide row spacing, those seedlings that weren’t killed by the initial dose of the herbicide, if we don’t go in and do anything about that, they will eventually reproduce, produce some seed and contribute to the problem,” he explains.
Gulden discusses what integrated weed management looks like in canola — row spacing, seeding populations, variety selection — and some of the other benefits (ie. bigger yield) from growing a dense canola stand in this video filmed at CanoLab in Brandon: