'We've been prepared': City credits proactive measures with quick catch on Dutch elm disease

Elm tree canopies can be seen in Edmonton in May 2024, just months before four cases of Dutch elm disease were confirmed in the city. (Evan Klippenstein/CTV News Edmonton)

The City of Edmonton says staying proactive has helped keep its 90,000 elm trees relatively untouched by the devastating Dutch elm disease (DED).

The disease, caused by a fungus, was first found in Edmonton this August.

"It was a matter of when, not if, it would arrive in the City of Edmonton, so we've been prepared for it," said Mark Beare, with the City of Edmonton.

The fungus clogs the tree's water system, and can kill a mature tree in as little as three weeks and wipe out entire populations over years.

This summer, four elm trees in central Edmonton (one private and three city-owned) tested positive for the disease.

The infected trees were removed, as well as 21 other elms within a one-kilometre radius.

"Just to make sure," Beare added. "Because of how this disease does spread, it's spread either through a beetle or through root grafts, so underground from tree to tree."

Elms in surrounding neighbourhoods were also surveyed. Out of 55,000 trees, the city said 55 showed signs of DED, but none of those tested positive.

Beare credits the success of the response to the preparation done by the city.

"We do proactive inspections of trees all throughout the city, the crews are trained in what to look for," he said. "We've had an action plan in place since 2020 on what to do in the event that Dutch elm disease did arrive."

Prior to August, Beare said Edmonton was home to the largest concentration of elms unaffected by DED in the world.

Beare said there is no way to fully eradicate the disease now that it's arrived, but it can be controlled.

"I think this is something that we're going to have to stay on top of for years to come, there is no cure for it," he said, adding that Edmontonians can help by educating themselves on DED and keeping their elms healthy.

"It's a shared responsibility."

Tell-tale signs of the disease include:

Crews are currently pruning city-owned elms. Bylaws require that private elm owners trim dead and dying branches from October through to March to help keep trees healthy.

Travellers are asked not to bring elm material or firewood into Alberta from other provinces with DED infections.

More information on protecting your elms from DED can be found on the Government of Alberta's website.

Trees with suspected cases of Dutch elm disease can be reported to the STOPDED Hotline at 1-877-837-ELMS (3567).

The Government of Alberta reports that one case of DED was reported in Wainwright in 1998.

That tree was removed, and the fungus was not found in the province again until two trees tested positive in Lethbridge in 2020.

Before that, Alberta and B.C. were the only two provinces in Canada that disease had not spread to.

According to the B.C. government, the fungus has remained undetected there.