Dutch elm disease detected in north Edmonton as city battles deadly tree fungus

A devastating and highly contagious tree fungus has been detected in north Edmonton, the latest case of a deadly disease that puts Edmonton's vast canopy of urban elms under threat.

In a statement this week, city officials confirmed that a new case of Dutch elm disease has been detected in Edmonton.  

The infected tree in the north Edmonton neighbourhood of Alberta Avenue, as well as any elms within a 20-metre radius, will be removed as part of ongoing efforts to contain the spread.

The infected tree was recently spotted by city crews along the boulevard. A positive result was received from a provincial lab on Wednesday, marking the sixth confirmed case of the disease since it was first detected in Edmonton last August.

The contagious fungal infection — spread by elm bark beetles and spores from infected wood — pose a major risk to other elm in the vicinity, the city said.

Extensive additional testing in the area is underway. 

City officials have been monitoring the infection in partnership with federal officials since it was first detected in the city last summer with case numbers expected to rise.

According to a statement Friday, a total of 369 elms have been removed in the city to date as part of ongoing containment efforts. The total includes two destroyed so far in Alberta Avenue.

"This additional confirmed case does not change our approach as we continue assessments, removals and testing in co-ordination with the province and the Canadian Food Inspection Agency," said Mark Beare, Edmonton's director of infrastructure operations, in a statement. 

"While any positive test is disappointing, we remain confident that this collaborative approach is helping to limit the spread of the disease."

Urban forests under threat

Dutch elm disease poses a threat to all species of elm in Alberta.

The fungus, caused by microfungi that infiltrate a tree and clogs its water-conducting systems, has killed millions of elms in North America over the past century and has begun to proliferate across Prairie cities.

In Edmonton, the potential losses are particularly acute. The capital region is home to more than 90,000 city-owned elms, accounting for more than 22 per cent of Edmonton's urban forest canopy.

The city has been bracing for years for the potential arrival of the destructive fungus as it crept west across the country, devastating urban forest canopies. 

An action plan, now being implemented to limit the damage, was first developed in 2020.

In an effort to slow the spread, crews have been conducting routine inspections along Edmonton's tree-lined streets and boulevards, watching for signs of infection.

More than 55,000 trees citywide have been assessed for signs of infection. Any elms that appear sickly – with telltale wilting yellow leaves – are tested, and trees believed to be infected are immediately destroyed. 

An ongoing program to remove deadwood in elms is also necessary to reduce the habitat of the beetles, which may spread the fungus, the city said. 

"City arborists, urban foresters and the pest management team remain vigilant as we continue implementing the established Dutch elm disease management plan, including intensified surveillance of elm trees," Beare said.  

The infection has to date been detected in northeast Edmonton in the Killarney and Yellowhead Corridor East neighbourhoods. 

Enhanced monitoring and assessments of trees within a one-kilometre radius of the infected trees remain in place, the city said. 

Edmontonians are encouraged to report any signs of infestation to 311.

Infected trees may have dead branches or browning leaves. Their trunks may have holes or sawdust on the bark from burrowing beetles.

The city is also reminding Edmontonians not to bring firewood from elsewhere, to properly prune elms during the colder seasons and properly dispose of any deadwood or clippings at the Edmonton Waste Management Centre.