Glyphosate Resistant Kochia Confirmed in Manitoba

Canola stubble
Reducing the number of glyphosate applications in any year, or never applying glyphosate alone in pre-seed burn-off may delay the development of glyphosate resistant weeds

It’s worrisome, though not terribly surprising, that Manitoba Agriculture, Food and Rural Development (MAFRD) announced today confirmed glyphosate resistant kochia biotypes were found in the province.

MAFRD jointly conducted a kochia survey across Manitoba in the fall of 2013, in conjunction with Agriculture and Agri-Food Canada (the Saskatoon Research Centre) and the University of Manitoba, and funded by the Western Grains Research Foundation and BASF Canada.

Plants from 283 different kochia populations were harvested, thrashed and planted over the winter. The resulting seedlings were tested for glyphosate resistance. Kochia plants from two of the 283 sites were found to be glyphosate resistant (GR). Both sites were in the Red River Valley.

Finding GR kochia was not unexpected as previous surveys in Alberta and Saskatchewan, North Dakota, South Dakota and Minnesota, have all identified GR kochia.

Herbicide resistant weeds are not a new issue in Manitoba, as Group 2 resistant kochia and Group 3 resistant green foxtail populations were identified as long ago as 1988. However, resistance to glyphosate is new, and if GR kochia populations become more common in the province, it will result in added management skills and expense for farmers. In-crop control of GR kochia can be difficult in broadleaf crops like canola, soybean or pulses and pre-seed or pre-emergent treatments may be necessary for adequate control. Kochia is also a tumbleweed — resistant biotypes can spread easily.

Though the level of GR kochia is low, farmers have an opportunity to minimize the spread of this weed, says MAFRD. Farmers should consider reducing the number of glyphosate applications in a single season and incorporate non-glyphosate herbicides in weed management programs when growing glyphosate-tolerant crops.  Farmers will also need to incorporate non-herbicidal measures like crop rotation, tillage and manual weeding if necessary to control populations.

Click here to see more stories, videos and interviews regarding herbicide resistance management.

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