Why Is Elm Pruning Different?
Elm trees are an important part of Calgary’s urban forest. In fact, they make up about 20% of the city’s tree canopy. But elms are vulnerable to Dutch elm disease, a deadly condition spread by the elm bark beetle. If elms are pruned at the wrong time, they can attract these beetles and increase the risk of infection. The solution? ALWAYS prune elm trees in winter, between October and March, when the beetles are dormant.
What Is Dutch Elm Disease?
Dutch elm disease is caused by a fungus carried by elm bark beetles. When these beetles are active (spring through summer), they are attracted to the scent of fresh cuts on elm trees. Once they land on the tree, they can introduce the disease, which clogs the tree’s water-conducting vessels and eventually kills it.
Why Can Elms Only Be Pruned in Winter?
1. Beetles Are Dormant
From October through March, beetles are not active. Pruning during this window eliminates the risk of attracting them with fresh cuts, protecting both your tree and Calgary’s larger canopy.
2. Preventing Community-Wide Loss
Because 20% of Calgary’s canopy is made up of elm trees, a widespread outbreak of Dutch elm disease would be devastating to the city’s landscape and property values. By following proper seasonal pruning, property managers and homeowners alike play a role in preserving Calgary’s urban forest.
3. Healthier Growth and Stronger Trees
Just like with other species, winter pruning helps arborists clearly see the tree’s structure, identify weak or diseased branches, and prepare the tree for strong growth in spring.
What Happens If You Prune Elms in Summer?
Pruning during the beetles’ active season puts elms at high risk. A single cut can attract beetles from the surrounding area, potentially exposing not just your trees but also neighboring ones. In some places, pruning elms outside the October-March window is prohibited by bylaw because of this risk.
How LECM Helps Protect Your Elms
At LECM, our Tree Care division follows industry best practices and Calgary’s guidelines for elm pruning. We schedule all elm pruning during the safe dormant season and use certified arborists who understand how to balance tree health with property protection.
Key Takeaways: Why Winter Elm Pruning Matters
- Elm bark beetles are dormant in winter → no risk of disease spread
- 20% of Calgary’s canopy is elm trees → community-wide responsibility
- Winter pruning → healthier, stronger growth in spring
- LECM provides certified, compliant service → peace of mind for property owners
Protect Your Elm Trees Today (if it’s Winter!)
Winter is the only safe season to prune elms. Don’t risk your trees, your property, or Calgary’s urban forest. Contact LECM today to schedule your winter elm pruning and protect your investment.
