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Liceria & Co.
Magazine
Confirming Herbicide
Resistance in Prairie Fields
Weed herbicide resistance remains an important consideration for
farmers in the prairies. Multiple independent surveys and economic
studies show that resistance is widespread, increasing, and
economically significant. The most visible proof for farmers is tall
wild oat plants and green kochia plants in their cereal fields at harvest. 
Insights from Moses Palmer,
Business Development Manager,  20/20 Seed Labs Inc.
Most farmers encounter herbicide resistant weeds every season during their production. Current estimates
suggest that over 70% (49 million acres) of prairie crop fields contain at least one herbicide resistant weed
species which breaks down to ≈ 72% of fields in Saskatchewan, ≈ 59% of fields in Alberta and ≈ 75% of fields in
Manitoba. Key weeds such as wild oats and kochia are showing high resistance frequencies. Data from recent
surveys show that 69% of wild oat populations are herbicide resistant with 77% of fields with Group 1
resistance and 30% having multiple resistance to Group 1 & 2. On the other hand, kochia appears to have
100% of populations showing resistance to ALS (Group 2) herbicides. Rapid adaptation and the adoption of
multiple mechanisms of resistance in these key weeds makes it more difficult and costly for farmers to control.
Testing at 20/20 Seed Labs confirms the results of
the Prairie Weed Surveys. Of all wild oat samples
tested in the fall of 2024 and 2025 in our greenhouse,
56% of all samples showed resistance to Group 1& 2
modes of action (MOA). 20/20 Seed Labs recently
launched a weed tissue test for herbicide
resistance in the following weed species to test in
the spring. Wild Oat (Groups 1 & 2), Kochia (Groups 2,
5, 9 & 14), Green Foxtail (Groups 1 & 2), Foxtail Barley
(Group 1), False Cleavers (Group 2), Downy Brome
(Group 9) and Waterhemp (Groups 9 & 14). 
Testing is in its early stages, but preliminary data
indicates that most growers are interested in
Group 14 resistance in kochia. So far, all samples
have had genes linked to PPO resistance. This trend
is one to watch for as most kochia plants are
already resistant to Group 2, 4 and 9 herbicides.
Widespread Group 14 resistance will further limit the
options for farmers to control herbicide resistant
kochia plants. It will become increasingly important
to utilize information from testing to support your
Integrated Weed Management (IWM) Program.  
Most farmers have a good sense of whether their choice of herbicides have been effective in weed control in the
spring when plants start to emerge. However, the visual indications of herbicide failure alone are not enough
to determine if resistance is present in the field. Poor control can be the result of several factors including
application errors, environmental conditions, and weed growth staging at the time of application. Herbicide
resistance testing is a foundational step in IWM, removing the guess work and providing accurate and early
detection of herbicide resistance. Information gathered from testing allows farmers and agronomists to adopt
a proactive approach to weed management instead of reacting after the fact. 
A comprehensive approach to testing combines the whole plant bioassay (phenotypic) and the plant
tissue molecular (genetic) testing methods. Together, these 2 tests provide a more detailed image of the
nature of resistance present in weed populations. Herbicide resistance is no longer just a future concern.
Most growers are already dealing with the cost of control and worried about the loss of herbicides that were
previously effective. By combining accurate diagnostics with sound agronomic advice, growers can make
smarter choices, extend the life of herbicide tools and protect the productivity of their operations for the long
term.  
Contact us at 20/20 Seed Labs with questions about herbicide resistance testing by 
emailing support@2020seedlabs.ca. www.2020seedlabs.ca

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