10 Signs a Tree Needs to Be Removed — Denver Arborist Guide
Not every sick or damaged tree needs to come down — but some do, and waiting too long turns a manageable removal into an emergency. ISA Member Arborist Eric Petruska explains the 10 clearest signs that a tree should be removed before it becomes a hazard.
What Are the Signs a Tree Needs to Be Removed?
The clearest signs a tree needs removal: more than half the canopy is dead or declining; the trunk shows large cavities, deep vertical cracks, or fungal shelves (a decay signature); the tree has begun leaning suddenly or the soil is heaving at its base (root failure in progress); major limbs keep failing; or trunk damage circles most of the stem. Any of these near a house, driveway, or play area moves from “monitor” to “act.” An ISA-member assessment distinguishes the savable cases — and it’s free.
When in doubt, get an assessment. Tree Service Denver LLC provides free on-site assessments — call (720) 807-2785. An arborist can tell you definitively whether a tree can be saved or needs to come down.
1. Dead or Dying Canopy
A tree with more than 50% dead branches or a rapidly thinning canopy is unlikely to recover. Dead wood doesn’t drop on a schedule — branches can fall at any time, especially during wind events. A tree that has lost its canopy in one season should be assessed immediately.
2. Significant Trunk Damage or Cavities
Large cavities, cracks, or splits in the main trunk indicate structural compromise. Some cavities are cosmetic; others mean the tree is hollow and cannot withstand wind loading. A trunk crack that runs vertically the length of the tree is a serious structural failure indicator.
3. Fungal Growth at the Base
Mushrooms, conks, or bracket fungi growing at the base of a tree or on major roots are a sign of internal wood decay. Root rot destroys the structural anchor of the tree — a tree with significant root decay can uproot without warning, often during saturated soil conditions after rain.
4. Leaning That Has Changed
Trees that have always had a slight lean are often structurally stable. A tree that has begun to lean — especially after a storm or period of heavy rain — indicates root failure or structural compromise on one side. This is an emergency situation requiring immediate assessment.
5. Exposed or Heaving Roots
Soil heaving or lifting on one side of a tree base, combined with any lean, indicates root plate failure. Roots that have been severed by construction, grade changes, or utility installation may no longer anchor the tree adequately.
6. Multiple Large Co-Dominant Stems
Trees with two or more major stems of equal diameter growing from the same point often develop included bark — a weak union that can split catastrophically under wind or snow load. If the union shows a crack or V-shape with visible bark inclusion, the tree is a splitting hazard.
7. Dead Top (Dieback)
A tree that is dead at the top (“stag-headed”) but green lower down is in advanced decline. This pattern is common in EAB-infested ash, drought-stressed cottonwood, and over-pruned trees. The dead crown sections are dry, brittle, and prone to dropping — and the tree is unlikely to recover its upper structure.
8. Root Zone Damage
Construction within the drip line of a tree, trenching through root zones, or significant grade changes can kill a tree’s feeder roots. Trees often decline 2–5 years after construction damage as the root system slowly fails. Signs include progressive dieback, leaf scorch, and premature fall color.
9. Location Over High-Value Targets
A marginally healthy tree located over a roof, driveway, or play area carries much higher risk than the same tree in an open field. The target value of what the tree could hit elevates the acceptable risk threshold — what might be a “watch and wait” tree in a back corner becomes a removal candidate when it’s over a bedroom.
10. Storm Damage
Trees that have lost more than 30% of their crown in a single storm event, have split at a major union, or have partial uprooting should be assessed before the next wind event. Not all storm-damaged trees need removal — but many do, and waiting for the next storm to decide is not a safe strategy.
1Can a tree with a hollow trunk be saved?
It depends on how much sound wood remains. If the hollow is contained and the remaining shell of wood is thick enough to support wind loading, the tree may be stable. Cabling can help manage structural weakness. An arborist assessment with a resistograph (internal decay detector) gives a definitive answer. Trees with less than 30% sound wood remaining are typically removal candidates.
2How do I know if my tree is a hazard?
A tree hazard has two components: a structural defect (crack, decay, root failure) AND a target (something valuable it could hit if it failed). A tree with a cavity in an open field poses low hazard. The same tree over your driveway poses high hazard. ISA member arborists are trained in formal tree risk assessment — a free on-site visit gives you a professional opinion on both factors.
How urgent is a sudden lean after a storm?
Can a half-dead tree recover?
Who is responsible if my dying tree hits the neighbor’s house?
Common False Alarms: What Looks Fatal but Isn’t
Not every alarming symptom is a death sentence, and knowing the false alarms saves good trees. A long-standing lean the tree grew with is architecture, not emergency — it’s new lean that kills. Mushrooms in the lawn near a tree usually feed on old buried roots, not the living one (fruiting on the trunk is the serious version). Early fall color and thin crowns after dry winters are often drought stress that watering and root-zone care reverse. Sapsucker holes in neat rings look dramatic and rarely matter; bark shedding on certain species is normal growth. The pattern: single symptoms mislead, combinations convict — which is why the assessment looks at the whole tree before anyone talks about saws.
When in doubt between alarm and false alarm, the tiebreaker is free.
A Homeowner’s 10-Minute Tree Triage Walk
Twice a year — after leaf-out and after leaf-drop — walk each significant tree with this loop: start at the ground (heaving soil, lifting roots, mushrooms at the base), read the trunk bottom-up (cracks, cavities, missing bark, fungal shelves, insect exit holes), scan the major unions (tight V-shapes with included bark are the split candidates), then the canopy (dead sections, hanging limbs, thinning versus last year), and finish with the lean check against a fixed reference like a fence post. Photograph anything questionable with your phone — the date-stamped comparison next season is diagnostic gold. Ten minutes per walk converts you from the owner surprised by a failure into the owner who booked the free assessment two seasons early — which, per everything above, is the cheap timeline.
File the photos in one album per tree — five years of twice-annual snapshots is a decline record no memory can match, and it’s exactly the documentation that settles insurance and neighbor questions later.
Questions? Call Eric Directly
ISA Member Arborist. Same-day response. Free written estimate, no obligation.
