By Sam Borsato - @BorsatoSam on Twitter

Treatments Nearing the End in Battle Against Elm Scale

Aug 16, 2016 | 3:03 PM

LETHBRIDGE – The City of Lethbridge’s aggressive treatment plan to tackle the current European Elm Scale infection is nearing completion.

The disease comes from an insect that feeds on the trees, and produces a sticky secretion that covers the leaves and bark in black mold. It can eventually kill weakened trees and cause branch dieback in healthy ones.

There are roughly 5,500 elm trees on City property, some of which are too small to treat or haven’t been affected. A combination of warmer winters, hotter than usual summers and a lack of treatment product has lead to the infestation.

Back in mid-June, City Council approved $380,000 in funds from its Environment Committee to bring in external contractors to help City staff inject roughly 3,600 public elm trees with the natural insecticide, TreeAzin.

More than 3,100 trees have been treated in the last eight weeks. The City has taken care of 800 infected trees, while the private contractor has worked on nearly 2,300.

Nighttime construction on Hwy 3 in Lethbridge starts April 17

Apr 17, 2025

SASHA launches #BuyABed fundraiser to support vulnerable Lethbridge residents

Apr 04, 2025

$20K grants available: TELUS STORYHIVE Pan-Asian Edition opens applications April 1

Mar 18, 2025

Both will continue with the TreeAzin treatments until the elms are no longer actively absorbing the insecticide.

“We’ve had some reports of honeydew excretions from these insects stopping within days of treatment, but that may also be coincidental with the insects’ life cycle,” says Kevin Jensen, Parks Operations Manager. “Insect numbers decrease only slightly during the first months after treatment. We should see significant decreases next spring.”

Jensen added that for this program to be most effective, residents should get affected elms on their private property treated, as well. Residents can contact a qualified arborist to administer the pesticide, send an e-mail to trees@lethbridge.ca, or call 403-320-3850 to take care of trees along City-owned green boulevards.

After this round of treatment is complete, the City will continue to monitor trees across Lethbridge, catalogue photos and samples, pressure wash small trees after this fall’s leaf drop, and develop a long-term rotating treatment schedule.

by Sam Borsato - @BorsatoSam on Twitter

Treatments Nearing the End in Battle Against Elm Scale

What's Happening