Quick answer: A tree probably needs to be removed if it is dead, has a cracked or hollow trunk, has fungus growing at the base, or has started to lean. Large dead branches, root damage and emerald ash borer in an ash tree are also strong warning signs. One sign alone calls for an inspection. Several together usually mean removal.
Removing a tree is permanent, so it is worth knowing which problems can be fixed with pruning and which cannot. This guide covers the eight signs arborists look for. If you already know the tree has to go, see tree removal in Denver.
What are the signs a tree needs to be removed?
- Large dead branches in the crown. Dead limbs thicker than your arm, or dieback spreading from the top down, show the tree is in decline.
- Cracks, splits or cavities in the trunk. A deep vertical crack or a hollow weakens the part of the tree that carries all the weight.
- Mushrooms or fungus at the base. Fungal growth on the trunk flare or roots is a sign of internal decay you cannot see.
- A new or worsening lean. Lifted or cracked soil on the side opposite the lean means the roots are letting go.
- Root damage. Roots cut by trenching, paving or construction, or roots that are soft and decayed, take away the tree’s anchor.
- No leaves in the growing season. A tree that does not leaf out, or sheds bark in sheets, is dead or close to it.
- Emerald ash borer in an ash tree. Look for D-shaped exit holes, winding tunnels under the bark and dieback at the top of the crown.
- The wrong tree in the wrong place. A large tree pushing against a foundation, growing into power lines or hanging over a roof can be a hazard even when it is healthy.
Which signs mean removal, and which can be fixed?
| What you see | Usual outcome |
|---|---|
| A few dead branches, sound trunk | Prune out the deadwood |
| Storm-broken limbs, most of the crown intact | Corrective pruning |
| Deep trunk crack or large hollow | Removal in most cases |
| Fungus at the base with dieback | Removal in most cases |
| New lean with lifting soil | Urgent removal |
| Dead tree | Removal |
When the trunk and roots are sound, tree pruning is often enough. After a snowstorm, see storm damage tree cleanup before deciding the tree is lost.
Is a dead tree dangerous?
Yes, and it gets more dangerous with time. Dead wood dries out and turns brittle, so limbs can drop without warning in wind or under snow. A dead tree is also harder to take down safely, which is one reason waiting tends to raise the cost of removal. In Denver, the City Forester can order the removal of trees that are dangerous or diseased.
What should Denver ash tree owners look for?
Emerald ash borer was confirmed in Denver in June 2025, and about 1 in 6 trees in the city is an ash. The Colorado State Forest Service lists the symptoms as branch dieback near the top of the tree, D-shaped exit holes about 1/8 inch wide, winding tunnels under the bark and new sprouts on the trunk. A healthy ash may be worth treating. A declining one is usually better removed. See ash tree removal and emerald ash borer help.
When is it an emergency?
Treat it as urgent if the trunk has freshly split, the tree has suddenly started to lean, the soil at the base is lifting, or a large broken limb is hanging over a house, driveway or sidewalk. Keep people away from the area and call for emergency tree removal. If the tree is touching a power line, stay well clear and report it to your utility first.
What happens after you decide to remove a tree?
Check whether the tree stands in the public right-of-way, because that changes whether you need a permit. Then read what to expect during tree removal so you know how the day will go.
Tree removal warning sign FAQs
How long can a dead tree stay standing?
There is no safe number. Some dead trees stand for years and others drop large limbs within months, depending on the species, the amount of decay and the weather. If a dead tree could hit a house, a driveway, a sidewalk or a play area, plan the removal now.
Can a half-dead tree be saved?
Sometimes. If the dead part is limited to certain branches and the trunk and roots are sound, pruning out the deadwood can be enough. If more than about half of the crown is dead, or the trunk is decayed, removal is usually the safer choice.
Is a leaning tree always dangerous?
No. A tree that has leaned for years and is growing strongly is often stable. A lean that is new or getting worse, especially with cracked or lifting soil on the opposite side, means the roots are failing and should be treated as urgent.
