While growers of glyphosate-tolerant soybeans, corn and cotton elsewhere in North America fret about the future of their favorite herbicide, Canadian canola producers have so far seen no evidence that glyphosate-resistant weeds are invading their fields.
Weed scientist Neil Harker of Agriculture and Agri-Food Canada credits this happy state of affairs to diversified crop and herbicide rotations.
On Jan. 20 at the Bayer weed resistance conference in Miami, Florida, he explained almost 100 per cent of canola acres are now seeded to herbicide-tolerant varieties, with Liberty Link and Roundup Ready accounting for about 45 per cent each.
And in contrast to corn/soy/ cotton country in the U.S., where almost every acre has been getting at least one and maybe several glyphosate applications every year, canola is generally grown in a one-in-three rotation.
He further noted that the most common crop rotation on the Prairies is canola/grain/grain or maybe a pulse crop. Herbicides used in these crops would likely hit any glyphosate-(or glufosinate-) resistant weeds if they did appear.
Harker, who works out of AAFC’s Lacombe Research Centre, said that while continuous canola might be the most profitable rotation in the short term, most growers understand the risks – of disease, if not resistant weeds.
Continued judicious use of glyphosate-and glufosinate-resistant canolas in recommended rotations with other crops should keep these herbicide tools effective for many more years, he suggested.