7 Critical Signs A Tree Needs To Be Removed (Expert Guide)

There is nothing quite as unsettling as watching a massive tree sway violently during a storm, wondering if this is the gust that finally brings it down on your roof.

While trees add immense value and beauty to a property, a dying or structurally compromised tree poses a severe threat to your family, your home, and your wallet. The difference between a simple pruning job and a catastrophic emergency often comes down to spotting the subtle warning signs before gravity takes over.

You don’t need the specialised training of professional arborists to spot the red flags; you just need to know where to look. In this guide, we break down the definitive signs that a tree has passed the point of no return and needs to be removed.

Quick Answer: How to Tell if a Tree Needs Removal

If more than 50% of the tree is damaged, showing signs of root rot, or has a sudden, significant lean, it likely requires removal. Hazardous trees often display deep cracks in the trunk, hollow cavities, or significant deadwood in the crown (known as “widowmakers”) that threaten nearby structures.

Top 5 Indicators of a Dangerous Tree:

Hollow Trunk: The tree sounds hollow or has large cavities.
Sudden Lean: The tree has shifted recently, creating soil heaving.
Fungal Growth: Large mushrooms near the base indicate internal rot.
Deep Cracks: Vertical splits visible in the bark or wood.
Crown Dieback: The upper branches are dead or losing leaves.

1. The 50% Rule: Damage Assessment

Before we dive into specific symptoms, professional arborists use a general rule of thumb regarding tree vitality.

If a tree is damaged, whether through disease, storm trauma, or structural defects, assess how much of the tree is affected. If more than 50% of the tree is damaged, it should likely be removed.

Why? Because a tree in this state rarely regains the vigour needed to support its own weight or fight off new infections.

2. Trunk Defects: Cracks, Cankers, and Cavities

The trunk is the main support pillar. If the pillar fails, the structure falls. Inspect the trunk for these three specific issues:

Vertical Cracks and Seams

Not all cracks are lethal, but deep, vertical splits that extend through the bark and into the wood are major structural failures. These suggest the tree is literally tearing itself apart under its own weight.

Large Cavities (Hollows)

A hollow tree isn’t necessarily a dead tree (the xylem and phloem on the outer rings might still be transporting nutrients), but it is a dangerous one. If one-third of the interior of the tree is hollow or rotten, its structural integrity is compromised.

Cankers

Cankers are sunken areas of dead bark. If a canker encompasses more than half of the trunk’s circumference, the nutrient flow is severed, and the tree is structurally weak.

Tip: Don’t Ignore “Included Bark.”

Many homeowners miss this. If you have a tree with two main stems (codominant stems) that grow in a “V” shape, look at the connection point. If the bark is rolling inward between them, it’s called Included Bark. This is a weak union that acts like a wedge; as the stems grow thicker, they push against each other and will eventually split. This often requires cabling or removal.

3. Root Health: The Hidden Danger

You can’t see the roots, but they tell the most important story. Root failure is the #1 cause of whole-tree failure (where the tree simply tips over, root ball and all).

Look for these warning signs at the base:

Heaving Soil: If the ground on one side of the tree looks swollen or lifted, the roots may be detaching from the earth.
Severed Roots: Have you recently done construction, trenching, or paving nearby? Cutting major roots destroys the tree’s anchor.
Girdling Roots: These are roots that wrap around the base of the trunk rather than growing outward. They literally strangle the tree, cutting off water and nutrient flow.

4. The Crown: Deadwood and Uneven Growth

Look up. The canopy offers clues about the tree’s overall health and stability.

The “Widowmakers”: This industry term refers to large, dead branches high in the canopy that are loosely attached. They can fall without warning, even on a calm day.
Crown Dieback: If the top branches are dead while the lower branches are green, the tree is suffering from stress (often root-related). This “dieback” usually progresses downward.
Lopsided Growth: A tree that is heavily weighted on one side due to poor pruning or storm damage is structurally unbalanced and prone to toppling.

5. Fungus: The Silent Killer

Fungi are nature’s decomposers. If you see them on your tree, it means something is decomposing, usually your tree.

Identifying the Danger

If you see large, shelf-like mushrooms growing on the trunk or clustering at the base of the tree, this is a sign of internal rot.

By the time you see the mushroom on the outside, the fungus has likely already rotted a significant portion of the tree’s core. Ganoderma is a common root rot fungus that is almost always a death sentence for the tree.

6. Leaning Trees: When to Worry

Not all leaning trees are dangerous. Some trees grow at an angle to reach sunlight (phototropism). However, the nature of the lean matters.

The “Safe” Lean vs. The “Danger” Lean

Feature	Natural Lean (Usually Safe)	Dangerous Lean (Removal Needed)
Speed	Developed slowly over the years.	Happened suddenly (e.g., after a storm).
Soil	Soil is flat and undisturbed.	Soil is heaving or cracked on the opposite side.
Roots	Roots look stable.	Roots are exposed or lifting.
Angle	Generally, less than 15 degrees.	Exceeds 15 degrees or is worsening.

7. Comparison: Pruning vs. Removal

Sometimes, you can save the tree. Other times, attempting to save it is a liability. Here is a quick decision matrix to help you decide.

You might need PRUNING if:

The damage is limited to one or two branches.
The trunk is solid, and the roots are healthy.
The tree is young and can recover vigorously.

You need REMOVAL if:

The trunk is hollow or compromised.
More than 30% of the crown is deadwood.
The tree is located within “striking distance” of your home or power lines.
You observe fungal conks on the main trunk.

Expert Insight: The “Target” Factor.

In the arboriculture world, a tree is only considered “hazardous” if it has a Target. A dead tree in the middle of a 50-acre forest is not a hazard; it’s a habitat. A dead tree 10 feet from your master bedroom is a hazard. Always evaluate what the tree will hit if it falls.

Conclusion

Deciding to remove a tree is never easy. It affects the aesthetics of your home and the shade in your yard. However, ignoring the signs of a hazardous tree can lead to catastrophic property damage or injury.

If you notice any of the critical signs mentioned above, especially heaving roots, deep trunk cracks, or fungal growth, do not wait for the next storm to test your luck.

Once the hazardous tree is gone, you will gain valuable open space perfect for finally implementing those BBQ area design ideas you’ve been dreaming about.

Your Next Step:

Don’t rely on guesswork. If you are unsure, contact a distinct Certified Arborist (ISA Certified) for a Tree Risk Assessment immediately.

FAQs

Q: Can a tree recover from a hollow trunk?

A: No, the heartwood of a tree (the centre) does not regenerate once it rots away. While a tree can live for years with a hollow trunk, the structural integrity is permanently compromised, making it dangerous in high winds.

Q: How much does it cost to remove a tree?

A: Tree removal costs vary wildly based on height, diameter, and location. On average, you can expect to pay between $400 and $2,000. Complex removals near houses or power lines can exceed $3,000 due to the need for cranes and specialised crews.

Q: What is the “Scratch Test” for trees?

A: The scratch test is a simple way to check if a branch is dead. Use your thumbnail or a knife to gently scratch the outer layer of bark. If the layer underneath is green and moist, the branch is alive. If it is brown and brittle, the branch is dead.

Q: Does homeowner’s insurance cover tree removal?

A: Generally, insurance only covers tree removal if the tree has fallen and damaged a covered structure (like your roof). They rarely cover the preventative removal of a dead tree. In fact, if a dead tree falls and you knew it was dead (negligence), they may deny your claim.

7 Critical Signs A Tree Needs To Be Removed (Expert Guide)