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Yellowdevil Hawkweed found in Alberta

Yellowdevil hawkweed has been found in the Crowsnest Pass area 
of Alberta. Learn how to control it before it spreads further

Yellowdevil hawkweed (Hieracium glomeratum) was recently found in southern Alberta, in the Crowsnest Pass area. In the Pacific Northwest, hawkweeds are some of the most troublesome weeds found. A perennial, yellowdevil hawkweed reproduces by seed, and vegetatively by rhizomes and root buds. It is thought that the weed most likely came into the province via B.C. or Montana.

“Most likely B.C. is the culprit,” says Nicole Kimmel, weed specialist with Alberta Agriculture and Rural Development. “It’s in a logging area, so most likely equipment is what it came in on.”

Identifying yellowdevil hawkweed

Yellowdevil hawkweeds have small dandelion-like heads, with hairy stems and leaves. All but one invasive species have yellow flowers, making it difficult to distinguish between other hawkweed varieties.

“It’s one of the very many invasive hawkweeds known to be in North America and this is the first documented report of this yellowdevil hawkweed down in the Crowsnest Pass in southern Alberta,” says Kimmel.

“Hawkweed can also reproduce by root fragments, so if any of those roots were broken off it has the ability to regenerate if they’re buried,” she says. “And it can send off a little stem underground and then it pops up a new plant so many inches away from the mother plant. That’s why they’re so invasive.”

Another problem is that they’re very versatile. They’ve been found in lawns, in pastures, on logging roads and alongside ditches. “There doesn’t seem to be any limiting factor to where you’ll find them,” says Kimmel. “They accommodate any soil type and any disturbance.”

The Crowsnest Pass discovery wasn’t small-scale, either. In fact, the size of the area the weed has covered is fairly substantial.

Legislation

Alberta’s Weed Control Act includes two classes of weeds: noxious weeds and prohibited noxious weeds. Hawkweeds are prohibited noxious weeds, which need to be eradicated as soon as they’re found.

Municipality or county weed inspectors have the authority to ask landowners to control weeds, or take action to control them (and send the bill to the landowner.)

Yellowdevil hawkweed is currently being treated as a prohibited noxious weed, but Kimmel says, technically, there is no legal authority for its control. Only orange, meadow, and mouse-ear hawkweeds are included in current regualtions. It will probably be 2014 before changes can be made to include yellowdevil hawkweed on this list.

Eradicating Yellowdevil Hawkweed

Since it’s a newly discovered plant, there are no registered herbicides for yellowdevil hawkweed. There are, however, herbicides that work on other hawkweeds. It all depends on how you read the label.

“Some have just listed hawkweed,” says Kimmel. “And some have listed orange hawkweed. To adhere to legal requirements of herbicide labels, one could use herbicides registered for ‘hawkweeds.’”

“Other than that,” she continues, “cultivation doesn’t work and mowing doesn’t work. Fertilizer has been known to work in combination with herbicide, but it needs that herbicide to knock down the weed. Then the fertilizer will help the other plants to compete if there’s enough grasses and forage around it to give them a boost.”

If you find yellowdevil hawkweed on your property, Kimmel advises you to consult your ag field representative.

“Well, hopefully they can consult with their ag field man because there are so many invasive hawkweeds — and hybrids are possible. I’d like them to consult with a professional before they get too excited.” †

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