Grainswest - Fall 2025

Fall 2025 Grains West 40 F armers are being backed into a corner, said Breanne Tidemann. “They are losing the go-to weed management solutions they’ve relied on for years—herbicides—and need to consider new tools to keep their fields clean.” With herbicide resistance on the rise, weed specialists such as Tidemann, a research scientist with Agriculture and Agri-Food Canada (AAFC), look for effective new management tools. This is where Integrated Weed Management (IWM) comes in. A holistic, sustainable approach to weed control, it combines multiple strategies. “Understanding and applying IWM principles is essential for long-term weed control, minimizing resistance and maintaining crop productivity,” said Tidemann. A robust, multi-year approach is needed to address weed growth and the weed seed bank, she added. IWM diversifies weed control methods that includes chemical, cultural, mechanical and biological FEATURE practices. These range from crop rotation and cover crops to tillage and tank mixing herbicides with multiple modes of action. IWM isn’t new, but its methods became less common decades ago when herbicides became the easiest, most effective weed control tool. “Life was good with herbicides, until it wasn’t,” said Tidemann. The development of herbicide resistance through the 1990s and 2000s brought renewed use of IWM strategies. The need to implement IWM is critical due to the increasing prevalence of herbicide-resistant weeds, said Tidemann. She sees new types of resistance and new weed biotypes annually. And yet, farmers still rely on herbicides as their main control method. Tidemann is one of many Canadian weed researchers in pursuit of effective IWM methods. “There’s never been only one option for weed control, and the most effective strategy requires diversity and layering strategies that work for individual farmers,” she said. NEW DIRECTIONS IN RESEARCH According to Lewis Baarda, kochia poses the greatest threat to crop production on the Prairies. This threat intensifies significantly when the weed becomes established in marginal areas. He manages a three-year, on-farm research project to evaluate IWM strategies against kochia in low-lying and saline areas. “Kochia is a smart weed, but it’s not a competitive one,” said Baarda, field tested manager with Farming Smarter. Once kochia patches are established on marginal land where crops aren’t present to choke it out, it’s hard to control due to its growing herbicide resistance to at least four chemical groups. “If kochia is established in marginal areas, like unproductive land, ditches and train tracks, it’s a problem for everyone.” Research has identified effective IWM kochia management practices, but this is the first Canadian study conducted on non-productive land. The weed’s WEED MANAGEMENT GOES HOLISTIC RESEARCHERS DEVELOP NEW STRATEGIES TO REGAIN CONTROL OVER RESISTANT SPECIES By JeanineMoyer Photo by Breanne Tidemann