Resistance Management School: It's all about diversity


Herbicide resistance is nothing new to Ontario farmers. It all started in 1973 when triazine-resistant lamb’s-quarters were found on a farm near Ripley, Ontario. Group 2 herbicide-resistant weeds were first documented in 1996.

Fast forward to 2018, and we find that the province is now home to a host of glyphosate-resistant weeds including Canada fleabane, giant ragweed, common ragweed and waterhemp. The number of weeds with resistance to multiple herbicide groups is also on the rise.

It’s a history lesson that Dr. Peter Sikkema, weed scientist at University of Guelph’s Ridgetown Campus, knows all to well. He’s our first guest on RealAgriculture’s new Resistance Management School series.

In this episode, Sikkema paints a picture of herbicide resistance in eastern Canada and its growing financial impact. For example, farmers can get near-perfect control of glyphosate-resistant Canada fleabane, “but it will cost about $30 for their pre-plant burn-down herbicide in contrast to what used to be $6,” says Sikkema. “That additional $24 is straight off the bottom line of every acre that is infested with glyphosate-resistant Canada fleabane.”

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Sikkema also discusses best management practices farmers should follow to control resistant weeds in their fields or prevent them from setting root. The key to success, he says, is diversity. That means farmers really need to adopt an integrated weed management program including: diverse crop rotation; rotating herbicide modes of action; use of multiple modes of action, ensuring full rates are used to kill weeds; and shooting for near-perfect weed control. Seeding rates, row widths and cover crops can also play a role in winning the war against herbicide resistance.

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