By the JCS Tree Care team · Led by an ISA Certified Arborist · Updated June 2026
The short version: A tree is becoming a hazard when it shows dead limbs, trunk cracks or cavities, fungus at the base, a new lean, root damage, or heavy deadwood over a target like your house. Some of these can be managed with pruning if caught early; others mean the tree should come down before it fails on its own. When in doubt, have it looked at — not every warning sign means removal. Get a free on-site assessment, or call (248) 965-9035.
1. Large dead branches or a dead top
Bare limbs in summer, or a dead crown, mean sections of the tree are already gone. Big deadwood falls without warning. A little deadwood can be pruned out; widespread dieback often signals a declining tree.
2. Cracks or splits in the trunk
Deep vertical cracks, or a seam where the trunk looks like it’s splitting, point to structural weakness. A cracked trunk can fail suddenly, especially in wind.
3. Cavities, hollows, or soft wood
An open hollow or area of soft, crumbling wood means decay inside the trunk or a major limb. A tree can stand with some hollowing, but extensive decay reduces the strength holding it up.
4. Mushrooms or conks at the base or on the trunk
Fungal growth — mushrooms at the roots, or shelf-like conks on the trunk — is often a visible sign of internal decay. It’s one of the clearest reasons to have a tree assessed.
5. A new or worsening lean
A tree that has always leaned and grew that way may be fine. A new lean, or one that’s getting worse, especially with soil cracking or heaving on one side of the base, can mean the roots are failing. That’s a serious hazard.
6. Root problems or recent digging nearby
Roots cut by construction, trenching, or new paving can quietly destabilize and kill a tree over a few seasons. Heaving soil, exposed or damaged roots, and sudden decline after nearby work are all warning signs.
7. It overhangs something it could damage
Even a healthy-looking tree is a higher-stakes risk when it leans over your roof, a driveway, a play area, or power lines. With a target underneath, smaller defects matter more, and it’s worth a closer look.
What to do if you see these signs
One sign doesn’t always mean removal — many trees can be pruned, monitored, or treated if the problem is caught early. But several signs together, or any sign on a tree over a target, is a reason for a professional assessment. An ISA Certified Arborist can tell you whether yours needs pruning, monitoring, or removal.
Frequently asked questions
What are the warning signs of a dangerous tree?
Large deadwood, trunk cracks, cavities or soft wood, fungus at the base, a new lean, root damage, and heavy limbs over a target like your house.
Does fungus on a tree mean it has to come down?
Not always, but mushrooms or conks often indicate internal decay and are a strong reason to have the tree assessed.
Is a leaning tree always dangerous?
No. A long-standing lean a tree grew into can be stable; a new or worsening lean with soil movement usually signals root failure and is dangerous.
Can a hazardous tree be saved?
Sometimes, if the problem is caught early — through pruning or treatment. An assessment determines whether the tree can be kept or should be removed.
