Dutch elm disease (DED) is a fungal infection that has wiped out American elms in most of their natural range in eastern North America. Alberta is one of the last places on earth that host healthy stands of these graceful trees.
American Elm Tree
The deadly Dutch elm disease is spread by one of three closely related beetles – the European elm bark Beetle, the native elm bark beetle and the banded elm bark beetle. Although these tiny dark-coloured beetles (only 2-3 mm long) can be found in Alberta, the fungus they transport has, so far not caused widespread infections of Alberta’s trees. In 1998 a tree in Wainwright was removed after being confirmed as being infected by the disease and again in 2020, two trees in Lethbridge tested positive for the disease and were removed and the areas are being monitored to ensure it has not spread. Unfortunately, in the Summer of 2024 the disease was discovered in Edmonton and containment measures are being put into place.
American Elm Leaf
The Society to Prevent Dutch Elm Disease monitors elms across Alberta and takes steps to prevent the spread of this disease through assessing pest populations, public education and other measures in an effort to keep Alberta’s elms DED-free.
Alberta is known to have over 600,000 Elm trees and the number is likely much higher. They are beautiful, large trees that can be reliably grown in our tough climate. They provide great shade and don’t require a large amount of maintenance. Losing this species from our limited list of suitable species in Calgary would be a terrible shame.
Key Points
- Alberta has some the last stands of healthy American elms anywhere.
- Do not keep elm firewood.
- Do not transport elm wood into Alberta.
- Observe the Provincial pruning ban on elms from April 1 through September 30.
- Report suspected DED to City officials (call 311)
Tree Damage
DED will kill an affected tree within two years. Typical signs of infection are branches on which the leaves appear wilted and turn yellow (called “flagging”). Report suspected infection to City personnel (call 311)
Control Measures
- Check your elms for signs of DED periodically and report any suspected signs of the disease or the beetle to City personnel (call 311)
- Do not keep elm firewood. It must be buried in a landfill or chipped into mulch.
- Do not transport elm firewood into Alberta. It is illegal.
- Do not prune elms between April 1 and September 30 while the Provincial ban on elm pruning is in effect.
- Keep elms healthy by watering during drought. Trees that are well hydrated may produce enough sap to smother beetles.
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