Dutch Elm Disease in Canada

Dutch Elm Disease arrived in eastern Canada in the 1940s and has spread westward across most of the country. Canadian management has been distinguished by Manitoba's exceptional preservation of the Winnipeg urban elm canopy — the largest surviving urban concentration of mature American elms in the world — through a long-running and well-funded municipal management program.

Arrival and spread

The first Canadian detection of Dutch Elm Disease was in Quebec in 1944, with subsequent eastern spread through New Brunswick, Nova Scotia, and Prince Edward Island over the following decade. The disease reached Ontario in the 1950s and the Prairie provinces in the 1970s. It has continued spreading westward and is now present in Alberta and British Columbia, with the western frontier still advancing.

The cooler Canadian climate has slowed the disease's progression compared with the eastern and midwestern United States. Beetle development is limited at higher latitudes, and active municipal programs have been able to keep ahead of natural spread in several major cities.

Provincial impact

Manitoba

Manitoba retains the world's largest mature urban American elm population, concentrated in Winnipeg. The provincial Dutch Elm Disease program, established in 1975, has maintained an aggressive sanitation, injection, and beetle-control regime that has slowed the disease to manageable annual losses.

Outside Winnipeg, the broader Manitoba elm population includes many shelterbelts and rural plantings, with active management coordinated through the Manitoba Forestry Branch.

Ontario

Ontario's elm population suffered substantial losses through the 1960s–1980s, particularly in cities including Toronto, Ottawa, and Hamilton. Most mature urban elms were lost; current management focuses on planting resistant cultivars for replacement and protecting remaining specimen trees through preventive fungicide injection.

Atlantic provinces

Dutch Elm Disease arrived earliest in the Atlantic provinces and caused substantial losses to the regional elm population through the mid-20th century. Active management continues at the municipal level.

Saskatchewan and Alberta

Both prairie provinces have detected DED in recent decades, with active monitoring programs aimed at slowing further spread. The cold prairie climate provides some advantage in beetle suppression.

British Columbia

DED is present in British Columbia but limited by climate and by the lower elm population in Pacific coastal regions. The province operates monitoring programs for early detection.

Research and breeding

Canadian research and breeding contributions include:

Agriculture and Agri-Food Canada — cold-hardy resistance breeding

Canadian Forest Service (Natural Resources Canada) — research at the Great Lakes Forestry Centre and other facilities

Université Laval (Quebec) — Ophiostoma novo-ulmi genome sequencing

Jeffries Nurseries (Manitoba) — origin of the cold-hardy 'Discovery' cultivar

Morden Research Station (Manitoba) — long-running prairie tree improvement program

Quarantine and regulations

The Canadian Food Inspection Agency operates phytosanitary regulations for the movement of elm wood. Provincial regulations supplement federal controls; Manitoba and Saskatchewan in particular maintain strict elm wood movement restrictions to protect their remaining populations. Movement of elm firewood across provincial boundaries is generally prohibited or restricted.

Current status

DED is established across most of Canada with significant elm populations. Manitoba's Winnipeg program remains the most successful preservation effort globally and serves as a model for other cities. Most other Canadian municipalities have transitioned from preservation to restoration, with replanting programs using Prairie Expedition™, 'Discovery', and other cold-hardy resistant cultivars.

City spotlights

Winnipeg — preserved urban elm canopy

Toronto — restoration-focused management

Related pages

Dutch Elm Disease by Region

What Is The Range of Dutch Elm Disease?

American Elm (Ulmus americana)

References

Hubbes, M. (1999). "The American elm and Dutch elm disease." The Forestry Chronicle, 75(2), 265–273.

Government of Manitoba. Dutch Elm Disease management program annual reports.

Bernier, L., et al. (2013). "Genome of Ophiostoma novo-ulmi, a causative agent of Dutch elm disease." Université Laval / Genome Canada.

Canadian Forest Service. Forest Insect and Disease Survey publications.