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Glyphosate Resistant (GR) Kochia Confirmed in Manitoba
Glyphosate-Resistant Kochia Distribution Map PDF (491 KB)
In 2013, Manitoba Agriculture jointly conducted a kochia survey across Manitoba with Agriculture and Agri-Food Canada (Saskatoon Research Centre) and the University of Manitoba, 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.
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.
Since then, Manitoba Agriculture has worked with the Pest Surveillance Initiative (PSI) and the University of Manitoba to pilot a qPCR (genetic) method to measure resistance to glyphosate in suspect kochia. Kochia plant material from seven populations submitted to PSI in 2015 and 2016 resulted in five new cases of GR kochia.
As GR kochia has been found in about two percent of the sites sampled, Manitoba farmers have an opportunity to minimize the spread of this weed. Farmers should consider reducing the number of glyphosate applications in a single season and incorporate/tank mix non-glyphosate herbicides in weed management programs and 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.
Herbicide resistant weeds are not a new issue in Manitoba, as Group 2 resistant kochia and Group 3 resistant green foxtail populations were identified in 1988. However, resistance to glyphosate is new and it remains an important herbicide in Manitoba crop production systems.
PSI’s qPCR GR kochia test is now available to farmers: www.mbpestlab.ca/field-testing/. Unlike other herbicide resistance tests, this method requires green plant material rather than seed, which allows for rapid analysis and in-season results.
