Lambsquarters Tops Farmers' List as Ontario’s Worst Weed


More than 300 Ontario farmers consider lambsquarters Ontario’s worst weed.

Results from a months-long online survey show lambsquarters narrowly edged out Canada fleabane by a half-dozen votes to take the title.

“They were neck in neck,” says survey coordinator David Bilyea, weed specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs in Ridgetown.

The last time such a survey was taken, in 2007, lambsquarters came in at No. 4. Bilyea figures its pervasiveness moved it into the top spot.

“Farmers everywhere fight it,” he says. “It’s our most common weed and it’s very persistent.”

The survey results reflect Ontario’s changing landscape for weeds, and farmers’ ability to identify them.

For example, Canada fleabane wasn’t even in the top 10 worst weeds in 2007. But with the popularity of no till, it moved from the sides of fields into the fields themselves. Its resistance to glyphosate has compounded the problem.

“Farmers who have it just don’t know what to do,” says Bilyea. “They are trying hard to get rid of it but control measures are not 100 per cent.”

And even farmers who don’t have Canada fleabane call it one of the province’s worst weeds…in eastern Ontario, where it’s much less common in fields, farmers still rated in the top 10.

“People are watching for it, and they’re concerned about getting it in their fields,” says Bilyea. In fact, farmers are so concerned about Canada fleabane that it knocked the 2007 champ, common ragweed, down to third place.

Bilyea says producers are worried about resistance to weeds other than Canada fleabane too, such as giant ragweed and common ragweed (both made the top 10 list).

Other changes include producers’ view of grasses. In 2007, what was identified as quackgrass came in at No. 2, and crabgrass squeaked in at No. 10. This year, though, neither made the worst-offender’s list, although producers still mentioned a wide variety of grasses.

Bilyea figures that stems from a higher level of producer knowledge.

“With greater access to electronic technology, farmers can more accurately identify the weeds in their fields,” he says. “All you have to do is take a photo of it, send it off and quickly you know what you’re dealing with. That wasn’t the case in 2007.”

Even with new technology though, some weeds are extremely difficult to distinguish between, such as the three pigweed varieties: green, smooth, and red-rooted. They appear on the survey simply as pigweeds, and come in at No. 5 as the province’s worst weed.

Overall, to help with identification, Bilyea and others maintain a weed garden – “trimmed and weeded,” he says — near the greenhouse complex on the University of Guelph Ridgetown campus.

There, visitors can view 208 specimens of weeds found in Ontario.

The garden is 40 years old this year, so it sports most conventional weeds along with new arrivals found in fields and lawns, other than nasty offenders such as poison ivy and dog strangling vine.

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