City wary of Elm Scale disease
City of Lethbridge crews are on high alert as they watch for signs of European Elm Scale affecting the city’s elm trees. European Elm Scale is an insect that threatened approximately two-thirds of the city’s public elm population last year.
Last year saw an aggressive campaign to fend off the infestation, and this year crews continue to work to protect the city’s elm tree population.
Last June, City Council provided additional funding to treat approximately 3,600 public trees with TreeAzin, a natural insecticide, to combat European Elm Scale.
“How each tree responded to treatment appears to be quite different,” Kevin Jensen, Parks Operations Manager stated in a news release. “Some absorbed the TreeAzin well and it was carried throughout the whole tree.
“We are seeing very little Scale left in those trees. Other trees didn’t have as good of an uptake. We saw this in trees that had lower moisture levels or damaged root systems.”
Elm trees treated last year will not be treated again this year as per the TreeAzin product recommendation.
The process involves drilling and injecting into the trunk which, if done unnecessarily, could cause more damage to the tree.
City staff have been closely monitoring the trees through the spring and sending away samples to check the level of chemical left in the leaves. This helps determine when it would be appropriate for another treatment, if needed.
The City will continue to monitor public elm trees and will implement a long-term rotating treatment schedule.
It is estimated there are 11,000 elm trees in Lethbridge. Approximately 5,500 of them are on public property.
For more information on signs and symptoms of Elm Scale and what can be done to protect trees, visit lethbridge.ca/elmscale.
If an elm tree is showing signs of stress from European Elm Scale, contact a qualified arborist who can administer a pesticide injection.
If the tree is located on a tree boulevard and needs attention, please email trees@lethbridge.ca or call 403-320-3850.