Herbicide resistance is not new to Ontario farmers. The first reported case goes back to 1957 when 2,4-D resistant wild carrot was found. But, for field crop producers, it started in 1973 when triazine-resistant lamb’s-quarters were found on a farm near Ripley, Ontario.
Group 2 resistant weeds were first documented in the province in 1996, but the roots of today’s challenge to manage herbicide resistance were really set in 2008, explains Dr. Peter Sikkema, professor, field crop weed management, University of Guelph, Ridgetown Campus. That’s when the first glyphosate-resistant giant ragweed was found in the province. Since then the glyphosate-resistant weed list has grown to include Canada fleabane (2010), common ragweed (2011) and waterhemp (2014).