For decades, glyphosate gave farmers a silver bullet in their battle against weeds.
The herbicide — which was introduced in 1974 and has been marketed under such names as Roundup, Touchdown, Credit, Polaris and Vantage Plus — proved infallible until the first resistant weeds were discovered in Australia in 1995. Other popped up in North America several years later, with glyphosate-resistant giant ragweed and Canada fleabane found in Ontario in 2008 and 2010 respectively.
Last Wednesday, Agriculture and Agri-Food Canada scientists confirmed that kochia plants taken from three fields in Southern Alberta have been confirmed to be glyphosate-resistant — the first found in Western Canada.
One of the researchers who made the discovery described the story yesterday during the Agronomy Update 2012 conference in Red Deer.
Hugh Beckie said ag officials were called after kochia in the three fields did not appear affected by glyphosate. He and his counterparts dug up 45 of the plants and took them to Saskatoon, where seeds were harvested, planted and sprayed.
They found that the new plants exhibited a moderate level of resistance. This could be overcome with a high enough concentration of glyphosate, said Beckie, but such levels aren’t practical and would likely only lead to an even higher level of resistance developing.
Kochia plants have been taken from other fields near the original three, he said, and are currently being analyzed.
“We will see if the resistance is occurring in more fields, which I suspect it is.”
Officials don’t know of the resistant kochia originated at that site or blew in from elsewhere, said Beckie.
The tumbleweed can travel considerable distances in the wind and drop about 10,000 seeds per plant.
Glyphosate-resistant kochia was previously confirmed in Kansas, Colorado and Nebraska, he said, with other suspected cases in North and South Dakota, Montana and Oklahoma.
Management options exist, said Beckie, who listed herbicide mixes that could be used for various crop species.
“What I’m more worried about are weeds like wild oats, where the options are severely limited,” he said.
“That’s one that I lie awake at nights sometimes worrying about.”
There are now 21 weed species in the world that have been found to be resistant to glyphosate. About half of these are in the United States.
hrichards@www.reddeeradvocate.com