Edmonton has identified its first cases of Dutch elm disease.
As of Aug. 30, the City of Edmonton said the disease had been detected on four trees in the Kilarney and Yellowhead Corridor East neighbourhoods.
Dutch elm disease is caused by a fungus that is spread among elm trees through their roots and by specific species of bark beetles that carry the fungus from tree to tree.
The first discovery happened during a routine inspection in early August, when city crews noticed symptoms of Dutch elm disease and live banded elm bark beetles in American elm trees.
From there, samples from the trees were sent to the Alberta Plant Health Laboratory. An indication of positive results came back on Aug. 15 and the Canadian Food Inspection Agency (CFIA) was notified the next day. The CFIA confirmed the presence of Dutch elm disease on Aug. 27.
The city said this is the first appearance of Dutch elm disease in Edmonton.
The city said it is not possible to determine how the disease ended up in Edmonton, but added it is often brought to new regions through firewood or by importing infected trees.
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“Edmontonians take great pride in our city’s urban forest. The detection of Dutch elm disease will understandably raise concerns, and we want to reassure Edmontonians that we have taken — and will continue to take — swift action to address the situation,” said Mark Beare, director of infrastructure operations.
“The City’s robust and proactive approach to inspections helped to identify the first cases early and we are currently assessing and evaluating all of the elms in the impacted neighbourhoods. Our priority is to contain the spread.”
The city said it has activated an “integrated action plan” to contain the spread of the disease. The work will be done in coordination with the CFIA, the Alberta Ministry of Agriculture and Irrigation, and the Society to Prevent Dutch Elm Disease.
Elm trees make up about 22 per cent of Edmonton’s maintained tree inventory, according to the city, accounting for about 90,000 trees.
In some of the city’s mature neighbourhoods, elms make up nearly 100 per cent of the boulevard trees.
All of the city-owned trees that tested positive for Dutch elm disease have been removed. City crews will now to inspect trees in the affected neighbourhoods to identify any that may display signs of the disease. This work is anticipated to be finished by the end of September.
To help prevent the spread of Dutch elm disease, people are asked to not bring firewood into the city from any other jurisdiction. Pruning elms between October and March to remove dead, dying and diseased branches can also help. All elm wood must be disposed of immediately by burning, burying, chipping or disposing at an Eco station.
Anyone who sees the signs of Dutch elm disease should call 311 to report it to the city. Signs of Dutch elm disease include:
- 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.
- Brown staining in the sapwood that can be seen by removing the bark of infected twigs.
- Beetle emergence holes, the size of the diameter of a pencil lead, and/or sawdust on the bark, indicate burrowing beetles.
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