Burndown herbicide applications revolutionized weed control in Western Canadian fields 30 years ago.  The simplicity and effectiveness of these herbicide applications makes it hard to change a good thing.  Today, we know that repeated use of a single product on a weed species can cause the weed to become resistant to the active ingredients in the herbicide.  Burndown applications provide a great opportunity to mix things up and head off resistance weeds before they become a problem.   

AAFC weed scientists Neil Harker and John O’Donovan estimated that the yield effect of one weed emerging a week before the crop is equivalent to that of 100 weeds emerging three weeks after the crop.  Early weed management is critical to the success of your crop but smart herbicide selection will help you manage resistance and maximize your returns. 

Why Resistance Management Matters 

Herbicide-resistant weeds like wild oats and kochia are becoming more common in the Prairies. Using the same herbicide repeatedly, especially glyphosate alone, can lead to resistance. This means your go-to herbicide might not work as well over time.  This information from Manage Resistance Now points out the pain resistant weeds can cause your bottom line. 

If resistant weeds start limiting your options for herbicides, your choices for crop rotations can become limited too.  Keep your options open and your land weed free to maximize your land value and your production capacity.  

Tank Mixing: A Smart Strategy 

Tank mixing glyphosate with other herbicides in your burndown application is a proven way to manage resistance. According to research, tank mixes are more effective at delaying resistance compared to using herbicides in rotation. For example, combining glyphosate with Group 14 and 15 herbicides can help control resistant weeds.  This tool from Bayer helps to explain the resistance and provides tips on tank mixing. 

The Sharpe’s agronomists are seeing resistant weeds become more common in Southeast Saskatchewan and Southwestern Manitoba.  Proactive management of resistant weeds can not only save you money in the long run but can also make your land more productive – check out this analysis if you still need convincing.  If you have questions about weeds on your farm contact a Sharpe’s agronomist to learn more.