Invasive fungus that kills elm trees detected in Edmonton for first time, city says

Dutch elm disease has been detected for the first time in Edmonton, leaving thousands of trees vulnerable to a fatal infestation the city expects to fight for years to come.

The fungus has been detected in several trees in the Killarney neighbourhood in northeast Edmonton, and along the Yellowhead Corridor East. As of Aug. 30, a total of four trees have tested positive for the disease, the city said in a statement Tuesday.

Dutch elm disease is a costly and deadly fungus that poses a threat to all species of elm trees in Alberta, including 90,000 elm trees owned by the city. In some of Edmonton's mature neighbourhoods, boulevards are lined solely with old, sweeping elms.

Mark Beare, the city's director of infrastructure operations, said city staff are preparing for a prolonged battle with the destructive fungus.

"This is going to be an ongoing fight from here on out," Beare said in an interview Tuesday.

"We do have an action plan," he said. "But I do believe this is something that we're going to be living with and battling for years to come."

Beare said the city has been bracing for years for the potential arrival of the destructive fungus as it crept westward across the country, devastating urban forest canopies. An action plan, now being implemented to limit the damage, was first developed in 2020. 

Beare said Edmonton has enjoyed the largest crop of elm trees untouched by the disease until now, and crews are eager to save all they can. 

"Often it has seemed that it's not a matter of if, but when," he said. "We've been prepared for this, we've been anticipating it, but it doesn't make it any less concerning when we actually do see it arrive in our city."

City officials are working with the Canadian Food Inspection Agency (CFIA) and the Alberta government to contain the spread and limit the damage.

Crews are assessing and evaluating all of the elms in the impacted neighbourhoods. In areas considered most at risk, trees showing signs of infection will be removed immediately. City officials expect the number of confirmed infections to rise.

"We don't have any specific numbers that we're bracing for at this time," Beare said. "We're talking hundreds of elm trees in the affected area, both public and private.

"Our goal right now is to conduct those visual surveys as quickly as possible ... It is very much an evolving situation and we would anticipate to get further positive tests based on how this does spread."

The fungus, which clogs a tree's water-conducting systems, has killed millions of elms in North America over the past century. Communities have spent millions in efforts to control the spread. Some have had to cull entire streets of elms.