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Dutch Elm Disease confirmed in Lethbridge

In early August, City of Lethbridge forestry staff observed symptoms of Dutch Elm Disease (DED) on two trees in north Lethbridge. Samples were tested at the Provincial and Federal labs and have since confirmed positive for DED.

Dutch Elm Disease poses a serious risk to the health of elm trees. It is caused by a fungus that can be carried on the bodies of Elm Bark Beetles who fly to new elm trees, spreading the infection as they go. Although there is no evidence as to how DED arrived in Lethbridge, it is often introduced into a community through the transport of fire wood or importing infected trees.

"Our urban forest is an extremely important part of our community," says Parks Manager Dave Ellis. "To protect it, we have been monitoring tree pests and insects for many years including Elm Bark Beetles. We commonly have the Elm Beetle, like many Alberta municipalities, but none of the beetles to date, were carriers of the fungus that causes DED."

Due to the seriousness of the disease, the two trees were removed and safely disposed of late last week.

The City of Lethbridge is now working with the Alberta Ministry of Agriculture and Forestry and the Canadian Food Inspection Agency (CFIA) to develop a response strategy in Lethbridge.

Elm trees can be injected with a fungicide in the spring to treat DED and the City is exploring this option. The City is also working to map the elm trees and assess their condition. This will help determine how and if they can be treated.

As the City continues to monitor the elm trees in the public urban forest, residents should:

  • Determine if they have any elm trees on their property. If you need help with this, you can contact an arborist.
  • Watch for signs of DED and report it to 311. This includes a sudden yellowing of the leaves, eventually causing the branch to wilt and leaves to turn brown.
  • Refrain from pruning elm trees between April 1 and September 30
  • Give the tree a good thorough watering before the fall frost to help it stay healthy through winter hibernation.
  • Do not keep elm wood for personal use. It is illegal to do so. Stored elm wood is the ideal breeding environment for elm bark beetles.

Lethbridge has been an active member of the Society To Prevent Dutch Elm Disease (STOPDED) since it was first formed. STOPDED is a non-profit organization whose mandate is to preserve and protect Alberta's elm trees from DED.

Elm trees make up a significant and important portion of the Lethbridge Urban Forest with nearly 6000 public elm trees and an estimated 5000 private trees making up 9.6% of the total urban forest. DED does not affect tree species other than elm.

If you need help identifying your trees or you think your tree may have DED, contact Lethbridge 311 or visit Additional information on DED from the Government of Canada can be found at

For Public Inquiries:

Call 311 |  Monday to Friday, 8 a.m. to 4:30 p.m.