A new study shows that Group 14-resistant kochia has developed and spread rapidly across Western Canada.
Group 14 is an important herbicide group for controlling the prolific weed because it already has widespread resistance to glyphosate, a Group 9 product, and has long had resistance to Group 2 chemistries.
Back in 2021, the first known case of Group 14-resistant kochia was discovered in West Central Saskatchewan. In 2022, it was discovered in North Dakota.
Charles Geddes, a research scientist in weed ecology and cropping systems at Agriculture and Agri-Food Canada in Lethbridge is a leading expert on herbicide resistant weeds. His team designed genetic tests to identify Group 14 resistance using leaf tissue samples.
This increased the speed and efficiency of identification.
In a post recently published on Linked-in, Geddes has published a map showing instances of Group14 resistance across all three Prairie provinces.
The greatest concentration is in the brown and dark brown soil zones where kochia thrives. Group 14 herbicides include saflufenacil (trade name Heat), carfentrazone (trade name Aim), and sulfentrazone (trade name Authority).
Products like Heat and Aim are mixed with glyphosate in the pre-seed burn-off to control kochia. Products containing sulfentrazone have residual activity to control the weed that way.
Charles Geddes says farmers will have an increased need for diversified herbicide programs with more emphasis on cultural and mechanical control.
