Monday, January 30, 2023

Dutch Elm Disease confirmed in Lethbridge; first known case in Alberta

Despite rigorous efforts to keep Dutch Elm Disease out of Lethbridge, two trees on the north side recently tested positive for the fungus and had to be destroyed.

City forestry staff noticed symptoms of DED in early August and samples sent to the provincial and federal labs confirmed the presence of the disease.

Dutch Elm Disease 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.

Lethbridge’s Parks Manager Dave Ellis says it’s a serious risk to the health of elm trees and infections can be devastating.

- Advertisement -

There are just under 6,000 public elm trees in the city, worth about $27 million, and an estimated 5,000 private trees which together make up about 10 per cent of Lethbridge’s total urban forest.

DED is often introduced to a community through the cross-provincial transport of fire wood or importation of infected trees, which is why laws exist prohibiting the use, storage, transportation or importation of elm firewood.

There is also a pruning ban on all elm trees between April 1 and Sept. 30.

Ellis says up until now, Alberta and British Columbia were the only two provinces in Canada to remain DED free since it was first observed in the eastern United States in 1928.

Residents are asked to monitor their elm trees for signs of DED, which includes sudden yellowing of leaves which causes the branch to wilt and leaves to turn brown, and to report the symptoms to 311.

- Advertisement -

More information on how to identify an elm tree, can be found on the City’s website.

In the meantime, the Ellis says the City is working to map elm trees and assess their condition while also exploring the possibility of injecting a fungicide in the spring to treat DED.

Parks staff say the easiest way to identify an elm tree is by its leaves. Photo credit (Sam Borsato)
- Advertisement -
- Advertisement -
- Advertisement -