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Why Are My Trees Dying from the Top Down? Causes, Risks & What to Do

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Noticing your tree’s upper branches dying while the lower parts remain green? This pattern, known as crown dieback, is a red flag for Calgary homeowners. It often signals deeper, systemic problems like drought stress, root damage, or pest invasion. And because the symptoms show up late in the game, waiting too long could mean losing the tree entirely.

If your trees are showing signs of top-down dieback, here’s what you need to know, and how Evergreen LTD can help protect your investment.


What Is Crown Dieback?

Crown dieback refers to the gradual death of a tree’s uppermost branches, typically starting at the tips and moving inward. It’s often the visible symptom of internal decline, caused by stress or damage that interrupts the tree’s ability to transport water and nutrients.


Dieback is branch tip death.

Decline is a whole-tree deterioration process, from root to crown.

Both are serious, and neither should be ignored.


Not sure what you’re seeing? Contact Evergreen LTD for a tree health assessment.


6 Leading Causes of Crown Dieback in Calgary Trees

Calgary’s variable climate and urban development patterns put unique stress on trees. These are the most common causes of top-down tree death in the region:


1. Drought & Water Stress

  • Common in Calgary’s semi-arid summers.

  • Trees reduce water supply to the top first.

  • Aspen and birch are particularly vulnerable.


Even established trees need deep watering during dry spells.


Need help setting up a watering plan? Evergreen LTD can advise on drought defense.


2. Winter Injury & Desiccation

  • Cold, dry winds damage upper branches.

  • Evergreens show needle browning at the crown.

  • Trees that don’t “harden off” before freeze may be hit hard.


Calgary’s freeze-thaw cycles make winter injury a top concern.


Talk to Evergreen LTD about fall inspections and winter prep pruning.


3. Root & Trunk Damage

  • Symptoms show in the crown, but the problem starts below.

  • Soil compaction, poor drainage, or root rot (e.g., Armillaria) reduce uptake.

  • Girdled roots or trunk wounds block flow to upper branches.


Sudden lean, mushrooms near base, or exposed roots.


Concerned about underground damage? Schedule a root zone inspection with us.


4. Fungal Pathogens & Cankers

  • Fungi like Hypoxylon and Phellinus tremulae invade weakened trees.

  • Aspen and poplar are frequent targets.

  • Trunk rot may be invisible until dieback appears.


Look for dark bark, sunken cankers, or conk fungi on trunks.


Catch infections early, our ISA-certified arborists can diagnose and recommend action.


5. Insect Damage & Wood-Borers

  • Borers create internal tunnels, killing nutrient pathways.

  • Birch and ash trees are common victims in Calgary.

  • Signs: D-shaped exit holes, sawdust (frass), or peeling bark.


Stressed trees are more likely to be infested.



6. Compound Stress (Decline Syndrome)

  • Multiple factors compound: drought + freeze + fungus = dieback.

  • This “slow death spiral” often affects trees on acreages or near construction zones.

  • Preventing early stress is the best defense.


No single cause? You may be dealing with a decline complex.


Book a full diagnostic consultation, our team gets to the root of the issue.


What Should Calgary Property Owners Watch For?

Crown dieback in Calgary is most common in:

  • Aspen, birch, and poplar (due to drought and fungal sensitivity)

  • Spruce, pine, and cedar (affected by winter desiccation)

  • Trees on acreages with uneven irrigation, compacted soil, or exposure


Inspect your trees for:

  • Bare or thinning tops

  • Bark cracks, cankers, or fungal growth

  • Signs of insect boring

  • Waterlogged or overly dry soil

  • Dieback worsening season to season



What Can You Do About It?

If you spot top-down dieback, act quickly:

Prune affected branches back to live tissue

Deep water during dry periods

Avoid soil compaction (don’t park or pile material near roots)

Apply mulch to regulate soil moisture and temperature

Inspect regularly for fungi, insects, or cracks

Avoid over-fertilizing stressed trees


And most importantly… Call in the experts early. Some trees can recover, others may need safe removal.


Why Trust Evergreen LTD?

  • ISA-Certified Arborists with deep knowledge of Calgary's trees

  • Diagnostic experience with drought, root issues, and pathogens

  • Safe pruning and removal following industry standards

  • Customized care plans for homes and rural properties


Whether it’s a struggling spruce or declining aspen, we help you make the right call, before it's too late.


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