What to Do If You Suspect Your Tree Has a Pest Problem
A healthy tree adds beauty, shade, and value to your property. But when pests invade, that same tree can quickly decline—turning from an asset into a hazard. Calgary’s unique climate doesn’t shield us from infestations; in fact, stressed trees in urban settings are often more vulnerable. The key to protecting your investment is recognizing problems early and calling in professional help before the damage becomes irreversible.
Why Tree Pests Are a Serious Concern
Tree pests don’t just chew leaves—they weaken structure, invite disease, and reduce a tree’s ability to photosynthesize. Over time, infestations can lead to canopy thinning, branch dieback, or even total tree failure. Left untreated, pests often spread to neighboring trees, threatening Calgary’s urban canopy as a whole.
Early detection is critical. Catching infestations at the first sign allows for targeted treatments that can save both the tree and the surrounding landscape.
Common Tree Pests in Calgary
Calgary homeowners should be familiar with several pests that appear regularly in local yards:
Aphids – Tiny, sap-sucking insects that cause leaves to curl and yellow. They produce sticky honeydew that attracts ants and leads to black, sooty mold.
Spider Mites – Almost invisible to the naked eye, these pests leave behind fine webbing and stippled, speckled foliage. Infestations worsen in hot, dry summers.
Leaf Miners – Insects that tunnel through leaves, leaving distinctive winding trails that reduce a tree’s ability to photosynthesize effectively.
Black Knot Fungus – Though technically a fungal disease, it behaves like a pest by spreading via airborne spores. It causes black, tar-like swellings on branches, especially in Mayday and Schubert chokecherries.
These pests weaken trees gradually, and without intervention, long-term damage is almost guaranteed.
The Growing Threat: Emerald Ash Borer (EAB)
The most concerning pest threat for Calgary is the Emerald Ash Borer (EAB). While EAB has not yet been confirmed in Alberta, it has devastated ash populations across Canada, killing tens of millions of trees.
EAB larvae feed beneath the bark, cutting off nutrient flow and effectively girdling trees from the inside. Once symptoms appear—such as canopy thinning, D-shaped exit holes in the bark, and increased woodpecker activity—it is often too late to save the tree.
Since ash trees make up a significant portion of Calgary’s urban canopy, the arrival of EAB would have major environmental and financial consequences. Preventative planning and monitoring are essential.
Signs Your Tree May Have a Pest Problem
Even if you’re not an expert, there are several warning signs homeowners can watch for:
Yellowing or curling leaves despite adequate watering.
Sticky residue (honeydew) on cars, decks, or patios beneath trees.
Canopy thinning or uneven leaf growth.
Black swellings or deformities on branches.
Visible tunneling or trails inside leaves.
Fine webbing in foliage.
If you notice any of these symptoms, it’s important to call a professional immediately. Waiting too long allows pests to spread and reduces treatment success.
Why DIY Pest Treatments Often Fail
It may be tempting to pick up chemical sprays from a garden center, but DIY pest treatments usually cause more harm than good. Common risks include:
Killing Beneficial Insects: Broad-spectrum insecticides wipe out pollinators and predators that naturally control pests.
Environmental Damage: Chemicals can leach into soil, affecting waterways and harming non-target plants.
Ineffective Application: Without proper diagnosis, homeowners often misapply treatments or target the wrong pest.
Masking Symptoms: Some DIY treatments temporarily reduce visible signs but don’t address the root problem.
Because trees are long-lived and complex organisms, professional diagnosis and treatment are the only reliable solutions.
Professional Solutions: Integrated Pest Management (IPM)
ISA Certified Arborists use a science-based approach called Integrated Pest Management (IPM) to handle infestations safely and effectively. IPM emphasizes long-term prevention over short-term fixes. Strategies include:
Accurate Identification: Determining the exact pest or disease before choosing a treatment.
Targeted Pruning: Removing infected branches to stop the spread.
Biological Controls: Encouraging beneficial insects that prey on pests.
Soil and Nutrient Care: Strengthening trees so they naturally resist pests.
Safe Products: Using environmentally friendly, slow-release treatments only when necessary.
By focusing on balance rather than blanket chemical use, IPM protects both your trees and the surrounding environment.
Why Call an ISA Certified Arborist?
Tree pest management isn’t just about killing insects—it’s about protecting the long-term health of your trees and property. An ISA Certified Arborist brings the training, equipment, and local knowledge needed to:
Diagnose pest issues accurately.
Recommend safe, effective, and Calgary-specific treatments.
Prevent future infestations through proactive care.
Ensure compliance with local regulations and bylaws.
Provide ongoing monitoring for high-risk trees like ash.
Professional guidance saves money in the long run by preventing tree loss, reducing property damage, and protecting your landscape investment.
Protect Your Trees Before It’s Too Late
Pests may be small, but their impact is massive. Ignoring the signs or relying on ineffective DIY treatments often results in the loss of otherwise healthy trees. By taking a proactive approach—watching for symptoms, scheduling regular inspections, and working with a Certified Arborist—you can protect your trees, your property, and your neighborhood.
The sooner pests are identified, the better your chances of saving the tree and preventing the problem from spreading. Don’t wait until it’s too late—protect your trees today.
