Ragweed becoming increasingly tough

Ragweed becoming increasingly tough

This is a story that will most likely make you sneeze. In Canada, ragweed plants have adapted to survive the the application of glyphosates, the most widely used herbicide in the world – and best-selling in Quebec.

The presence of ragweed (whose pollen causes hay fever) was very stubborn in Ontario last summer.

Three other glyphosate resistance plant species have been identified, and are rapidly spreading across fields in Canada. The giant ragweed – identified in 82 locations last summer – the Canadian fleabane – found in the 151 locations two years after its first appearance – and the kochia, where it’s dispertion potential in Western Canada “is phenomenal,” according to François Tardif, Professor of the  Department of Plant Sciences at Guelph University.

In Quebec, “we suspect that there are glyphosate-resistant weeds, but laboratory test have not yet confirmed this” said Danielle Bernier, agronomist de la phytoprotection du ministère de l’Agriculture. Species, including the Canadian fleabane with their countless seeds can be spread over 500 kilometers by the wind. “We are very concerned,” said the specialist.

Already, glyphosate treatments are ineffective in commercial crops (corn, soybeans, wheat, etc…) And Christmas tree plantations, according to a survey by MAPAQ with 50 specialists in weed control.

In the United States, there are currently 28 species that are resistant to glyphosates. To the point where companies like Monsanto and DowAgriculture now rely on genetically modified seeds to resist weeds.

In Quebec, six weeds have developed the ability to survive the application of herbicides other than Roundup. “It is not a disaster, but year in and year out, we see a more resistant species and two or three new sites affected,” says Bernier.

The consequence of this is that farmers must increase the dose and the number of herbicides applied to fields, which increases “the risk related to human health and the environment,” says a statement MAPAQ.

Stéphane Bisaillon a farmer on the South Shore of Montreal, has already been fighting with weeds that are resistant to the herbicide: atrazine. To prevent further cases of resistance, “I work with recommended doses and [he] switched presticide brands,” he reflects.

It’s very expensive. “An application of glyphosate costs $4 per acre, said Joel Johnson, brand manager for herbicides at BASF Canada. If we add the Optill herbicide (which contains two other families of herbicide) to fight against the resistance, the bill rises to $13 or $14 an acre.

“But it’s nothing compared to what is happening in Georgia, said Mr. Johnson. I recently went and they have weeds that are resistant to five different herbicides. They are now required to do all of their weeding by hand, and this is much more expensive even though they do hire foreign labour.”
LifeinQuebec.com Staff Writer

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