A specialist in forest health warns that the current strategy employed by the City of Edmonton to combat Dutch elm disease could have enduring adverse effects on the city’s tree cover. Since 2024, Edmonton has confirmed 16 cases of Dutch elm disease, with nine cases identified this year. Approximately 22% of Edmonton’s municipal tree canopy comprises elm trees, primarily American elms known for their tall, upright stature and expansive canopy.

Although not native to Alberta, American elm trees are favored for urban landscapes due to their aesthetic appeal. Dutch elm disease, carried by bark beetles, obstructs the trees’ water transport system, leading to wilting and eventual death. Presently, Edmonton’s focus is on removing infected trees, with healthy elm trees within 20 meters of infected ones also being removed as a precautionary measure.

Nadir Erbilgin, a forest health professor at the University of Alberta, suggests a different approach. He proposes using trap trees to target the source of infection – the bark beetles. By baiting infested trees with beetle pheromones to attract and subsequently remove them, the spread of the disease can be curtailed.

Erbilgin argues that the widespread removal approach adopted by many North American cities risks killing more healthy trees than the disease itself, potentially eliminating trees resistant to the disease. Mike Jenkins, a senior scientist with the City of Edmonton, acknowledged that the current strategy led to the removal of healthy trees in Rossdale, including mature elm trees.

Jenkins mentioned that enhanced surveillance enables early disease detection, preventing further spread. The city plans to incorporate trap trees in its approach next year, focusing on using Siberian elms, which are largely found on private properties. To address the issue, pruning dead wood from Siberian elms before the spring emergence of beetles is planned.

Residents are urged to participate in combatting Dutch elm disease by maintaining their elm trees, conducting regular inspections, and reporting any suspected cases to the city. Elm pruning is prohibited between April and September in Edmonton, but full-scale removal is allowed during this period. Disposal of elm wood can be done at the Edmonton Waste Management Centre.