Manitoba Agriculture, Food and Rural Development (MAFRD) jointly conducted a kochia survey across Manitoba in the fall of 2013 in 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.
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.
If GR kochia populations become more common in the province, it will result in added management skills and expense for Manitoba 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.
As GR kochia has been found in less than one per cent 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 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.
Moving forward, MAFRD staff will continue to monitor the two sites where GR kochia was found and work with the affected and neighbouring producers this spring to discuss possible containment procedures. The department will also develop an extension program on herbicide-tolerant weeds, using GR kochia as an example. The program will be aimed at industry agronomists, grower associations and producers and is expected to be ready later this spring.
For more information about GR kochia and related agronomic advice, please contact Nasir Shaikh, provincial weed specialist, at 204 750-2715 or Nasir Shaikh.