Category: invasive species

July 17, 2025

The City of Edmonton has confirmed an elm tree in the Alberta Avenue neighborhood has tested positive for Dutch elm disease (DED). This is the sixth tree confirmed to have Dutch elm disease since it was first discovered in Edmonton in August 2024.

The infected tree is located along the boulevard. It, as well as elm trees within 20 metres of the infected tree, will be removed promptly as part of ongoing efforts to contain the spread of the deadly fungal disease. Extensive additional testing of trees in the vicinity is underway.

“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. This additional confirmed case does not change our approach as we continue assessments, removals and testing in coordination with the province and the Canadian Food Inspection Agency,” said Mark Beare, Director of Infrastructure Operations. “While any positive test is disappointing, we remain confident that this collaborative approach is helping to limit the spread of the disease.”

Prompt removal of infected trees, and elm trees in the immediate vicinity, is essential for the health and safety of Edmonton's urban forest, as elm trees constitute 22 per cent of our Open Space and Boulevard Tree Inventory, totaling approximately 90,000 elm trees. Dutch elm disease is a contagious fungal infection that poses a major risk to other elm trees in the vicinity. An ongoing diligent pruning program to remove the deadwood in elms is necessary to reduce the habitat of the beetles which may spread the fungus.

Disposal of all removed elms occurs at the Edmonton Waste Management Centre in accordance with special handling procedures. Enhanced monitoring and assessments of trees in a one-kilometre radius of the infected trees are in place.

The previous five positive cases of Dutch elm disease were located in the Killarney and Yellowhead Corridor East neighbourhoods. The sixth tree was identified as presenting signs of the disease by City crews while conducting a planned visual assessment of trees in the Alberta Avenue neighbourhood. Staff with the City’s Integrated Pest Management Lab submitted samples from the tree to the provincial lab for testing. A positive result was received from the Government of Alberta on July 16, 2025.

What residents can do

Containing the spread of Dutch elm disease is a community effort. There are three ways residents can help stop the spread of the disease:

1. Do not bring firewood from another jurisdiction.

○ Beetles that carry Dutch elm disease are most likely to be brought to Edmonton in firewood, so remember to always “burn it where you buy it.”

2. Remove bark beetle habitat.

○ Prune elm trees between October and March to remove dead, dying and diseased branches (video).

○ Provincial law and municipal bylaw require elm tree owners to prune dead and dying branches from October through March.

○ All elm wood must be disposed of immediately by burning, burying, chipping or disposal at the Edmonton Waste Management Centre.

○ Do not combine elm wood with food scraps or other collected waste.

3. If you see signs of Dutch elm disease, call 311.

Signs of Dutch elm disease:

○ Brown staining in the sapwood that can be seen by removing the bark of infected twigs.

○ From the latter half of June to the middle of July, the leaves on one or more branches may wilt, droop and curl. The leaves then turn brown and usually remain on the tree.

○ If the tree is infected later in the summer, the leaves will droop, turn yellow and drop prematurely. Late season infections are easily confused with normal seasonal changes.

○ Beetle emergence holes, the size of the diameter of a pencil lead, and/or sawdust on the bark, indicate burrowing beetles.

For more information: edmonton.ca/dutchelm

If you see signs of DED in other parts of the province, call the STOPDED hotline 1-877-837-ELMS (3567)

In August of 2024, four trees in the Killarney and Yellowhead Corridor East neighbourhoods in the City Edmonton, were identified to be infected with Dutch elm disease (DED). Although it is not possible to determine how the disease arrived in Edmonton, DED is often brought to new regions through the transport of firewood or by importing infected elm trees. Three of the elm trees were city-owned, and one privately owned.

Sarah McPike, Biological Sciences Technician with the City of Edmonton and a Director of the Society to Prevent Dutch Elm Disease (STOPDED) spotted the initial suspect DED infected tree while driving through the neighborhood.  This tree was completely dead tree with a 55 cm DBH. Sarah observed the tree had peeling bark, with galleries, and numerous larvae and adults of banded elm bark beetle present.

Samples from this tree were submitted to the Alberta Plant Health Lab (APHL) also located in Edmonton. Since the tree sample was dry and dead no cultures were able to be recovered. Technically, the tree sample came back from the lab as negative for DED, but was strongly suspected that it actually died of DED infection. This tree is not included in the number of the 4 positive trees in Edmonton.

After an intense surveillance in the area 3 city owned trees along 127 Ave were sampled and tested positive.  They ranged from 15 and 25 cm DBH. Two of them were about 150 m from the initial tree, equidistant east and west from that tree. The third was about 100 m further west.

The fourth positive tree was found on private property 500 m to the northwest of the western-most positive tree on 128 Ave, and was about 35 cm DBH. A notice was sent to the property owner to remove and dispose of the infected tree. Removal was supervised by the City of Edmonton and CFIA staff.

The initial tree, as well as all the trees that tested positive for DED have been removed and disposed off as per the Provincial DED Prevention and Control Measures.  Any elms within 20 meters of these elms were also removed as a precaution against the disease having spread by root graft.

Surveillance and monitoring were intensified in the region of the positive trees.  There are approximately 50 or 60 city elm trees (all 15 - 25 cm DBH) between the positive trees. There are a total of approximately 175 elms on that 127 Ave boulevard. 30+ additional trees with wilt symptoms were submitted to the APHL and all came back negative. Trees with even minor symptoms have been placed on a watch list for continued surveillance.  Several trees with high levels of decline have been removed, even though they did not test positive.

All of the city elms on 127 Ave have been injected with TreeAzin to help combat European elm scale, which all of those trees had present.

It is important to note that all suspect DED elm trees, both public and private are the responsibility of the municipality to sample. Under the Alberta Agricultural Pests Act (APA) “Pest and Nuisance Control Regulation (PNCR)” the DED pathogen is a named declared pest. All municipalities, counties and MDs in the province of Alberta have the responsibility and authority to prevent and control DED under the APA. The APHL accepts samples only from municipalities, counties, MD’s ad Special Areas, not from the home owner or private pruning companies.

https://open.alberta.ca/publications/dutch-elm-disease-prevention-control-measures-responsibilities-authority-apa

Since all Provincial and Federal DED requirements have been followed Alberta is still considered DED free at this point. The City of Edmonton will be doing extensive surveillance for DED and monitoring for the elm bark beetles in the following years.