Herbicide-resistant weeds can spread quickly and rapidly, infesting entire fields and neighbouring land. Early detection and rapid management responses are critically important to eradicating new issues before they move beyond the field of origin. Herbicide-resistant weed spread is exacerbated by late identification of resistance due to a cumbersome process of resistance diagnostics using traditional whole-plant bioassays.
A recently completed project has successfully developed a sampling kit and tests to rapidly detect herbicide resistance in 14 key weed biotypes common to Western Canada. These biotypes span resistance to Group 1, Group 2, and Group 9 herbicides, including problematic species such as foxtail barley, kochia, downy brome, and redroot pigweed. Unlike current commercial testing for herbicide resistance, which is often too costly and slow for in-season decision-making, the newly developed tests can identify the type of herbicide resistance within 1–2 weeks of sample collection.
The project has optimized sampling and shipping protocols to ensure high DNA quality from field to lab and validated the molecular tests using both weed survey and farmer-submitted samples. A comprehensive reference manual detailing the molecular markers, lab methods, and visual interpretation of results is being finalized and will be made available to diagnostic labs through licensing agreements with Agriculture and Agri-Food Canada. This technology is already attracting commercial interest. Once available at commercial labs, this will allow farmers to make timely, informed weed management decisions, negate unnecessary or inappropriate herbicide use, and respond more effectively to herbicide-resistant weed populations. External sources have funded a follow-up project to expand and refine this work over the next four years.