Prairie Weed Surveys
Term: 5 years, ending August 2023
Status: Completed
Researcher(s): Julia Leeson, Hugh Beckie, AAFC Saskatoon SK; Kim Brown-Livingston, Manitoba Agriculture; Chris Neeser, Alberta Agriculture & Forestry; Breanne Tidemann, AAFC Lacombe AB; Charles Geddes, AAFC Lethbridge AB.
SaskCanola Investment: $62,825
Total Project Cost: $749,925
Funding Partners: Western Grains Research Foundation, Saskatchewan Wheat Development Commission, Saskatchewan Pulse Crop Development Board, Manitoba Wheat and Barley Growers Association, Manitoba Pulse and Soybean Growers, Alberta Grains, and Alberta Pulse Growers Commission.
Grower Benefits
Regular weed surveys have been conducted in annual crops across the Prairies using the same methodology since the 1970s, enabling the identification of shifts in weed communities. The most recent survey in the Prairie provinces was from 2019-2023.
The consistent presence of green foxtail, wild oat, wild buckwheat and lamb’s-quarter in the top five most abundant weeds in the past fifty years reflects the widespread distribution and resilience of these species.
Volunteer canola has been increasing in abundance, ranking second overall in recent surveys, and the most abundant weed in wheat, barley, soybean, field pea and lentil crops.
Kochia was the sixth most abundant weed in the Prairie provinces in the recent surveys, ranking higher than any previous survey. The rapid evolution and spread of herbicide-resistant kochia biotypes highlights the need to develop alternative weed management solutions.
The Prairie Weed Monitoring Network hosted by WGRF was launched in spring 2024. The website will include data from each of the Prairie Weed Surveys starting in the 1970’s.
Project Summary
Weed surveys have been regularly conducted in annual crops in the Prairie Provinces since the 1970’s. In the 1990’s, a herbicide resistance survey program was also started across the Prairies. The most recent set of general weed surveys was conducted from 2019 to 2023, including herbicide resistance surveys on a subset of the same fields. Similar methodology has been used since the 1970’s, enabling the identification of shifts in weed communities. Quantitative field surveys of weed populations are used to reveal the current size, extent, and order of importance of species in provinces, ecoregions and jurisdictional areas.
Across the Prairie Provinces from 2019 to 2023, 4098 fields of annual crops were surveyed for general weed abundance. Fields in Saskatchewan were surveyed in 2019 and 2021, Manitoba in 2022 and Alberta in 2023 and included: spring wheat, barley, durum, oat, canola, flax, mustard, soybean, lentil, pea, chickpea, corn, pinto bean and sunflower. Weed data was summarized using a relative abundance index based on frequency, field uniformity and density.
The results of the recent weed surveys identified green foxtail as the most abundant weed across the Prairies, which was the same in each of the previous surveys. Green foxtail was the most abundant weed in oat, corn and flax crops and ranked second in wheat, field pea and lentil crops. Volunteer canola ranked second overall and was the most abundant weed in wheat, barley, soybean, field pea and lentil crops. Wild oats and wild buckwheat ranked third and fourth across all annual crops, slightly lower than previous surveys due to the increase in volunteer canola. Lamb’s-quarters ranked fifth, a position it has held in five of the six surveys. The consistent presence of green foxtail, wild oat, wild buckwheat and lamb’s-quarter in the top five most abundant weeds in the past fifty years reflects the widespread distribution and resilience of these species.
Kochia was the sixth most abundant weed in the Prairie provinces from 2019-2023, ranking higher than any previous survey. Although there has been some fluctuation in the abundance rank of kochia over the survey years, overall it has rapidly been increasing in abundance and becoming a problem across all of the Prairie Provinces. The rapid evolution and spread of herbicide-resistant kochia biotypes highlights the need to develop alternative weed management solutions.
The weed surveys also highlighted some differences in the top weeds in each province in each year of the survey, depending on the weather conditions. For example, kochia was in the top 5 weeds species in Saskatchewan in 2021 due to the dry conditions. In Manitoba, redroot pigweed was more common, ranking fifth. Due to wet conditions in Alberta boreal regions in 2023, chickweed was the most abundant weed.
Regular and ongoing weed surveys are necessary to detect changes in weed populations and are providing data critical to developing ecologically and economically sustainable strategies to manage agricultural weeds. The data set supports research and education priorities, develops recommendations, and designs weed management strategies in the research, extension, and agri-business communities. Future surveys could also determine the impact of emerging herbicide resistant weeds, and any mitigation practices that are adopted.
In the spring of 2024, the Prairie Weed Monitoring Network hosted by WGRF was launched to increase accessibility to weed survey data, including herbicide resistance data. This network of federal, provincial, and academic weed scientists and specialists is committed to generating new knowledge on troublesome weeds across the Canadian Prairies.