How Can I Tell If A Tree Is Dangerous?

Common warning signs include trunk cracks, dead branches, fungal growth around the base, exposed roots, hollow cavities, and a sudden lean. If you notice any of these issues, it's best to arrange a professional inspection.

Does A Leaning Tree Always Need To Be Removed?

No. Some trees naturally grow at an angle. However, if the lean develops suddenly or is accompanied by lifting soil or exposed roots, it should be assessed by a qualified tree surgeon.

Are Mushrooms Around A Tree A Sign Of Danger?

Fungi growing around the base can indicate internal decay affecting the roots or trunk. While not every mushroom means a plant is unsafe, it should be professionally inspected.

Can A Tree Look Healthy But Still Be Dangerous?

Yes. Internal decay and root damage are not always visible externally, which is why professional surveys are recommended if you have concerns.

Can I Remove Dangerous Branches Myself?

Working on unstable or damaged trees can be extremely dangerous. Large branches and hazardous trees should always be dealt with by qualified professionals using the correct equipment.

How To Spot The Signs A Tree Is Dangerous: Expert Advice From M.A.C Tree Care

Spotting the signs a tree is dangerous can help prevent damage to your property and reduce the risk of injury. While many trees naturally shed leaves, branches, or fruit throughout the year, certain warning signs can indicate serious structural problems that require professional attention. At M.A.C Tree Care, we provide expert inspections, surveys, and tree surgery services for homeowners, schools, landlords, and businesses across Sidcup, Kent, and the surrounding areas. This guide explains the most common signs, what causes trees to become unsafe, and when it's time to contact a qualified tree surgeon.

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What Are The Dangerous Signs?

Not every tree with a few dead branches or seasonal leaf loss is dangerous. However, when a it develops structural weaknesses, root instability, or extensive decay, it can pose a serious risk to people, vehicles, buildings, and neighbouring properties.

The most common signs include:

Deep cracks or splits in the trunk
Mushrooms or fungal brackets growing around the base
Dead or hanging branches
A sudden lean or movement after storms
Exposed or lifting roots
Hollow cavities within the trunk
Large areas of missing bark
Significant dieback in the canopy
Oozing sap from damaged areas

If you notice one or more of these warning signs, it's important to arrange a professional inspection before the condition worsens.

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Root Problems

Healthy roots keep a plant firmly anchored in the ground. If the root system becomes damaged or begins to decay, the entire plant can become unstable.

Warning signs around the base include:

Raised or cracked soil
Roots lifting out of the ground (root heave)
Soil moving on one side of the tree
Fungal growth or mushrooms around the base
Soft, decaying wood near ground level

These symptoms often suggest that the tree's anchoring system has weakened and may no longer be able to support the weight of the tree during strong winds or severe weather.

Trunk Damage

The trunk carries the weight of the entire tree, making it one of the most important areas to inspect.

Signs of structural weakness include:

Deep vertical cracks
Large splits
Hollow cavities
Missing bark
Areas of soft or decaying wood
Sap leaking from wounds

Although some mature trees can live with small cavities, extensive decay or large structural defects may significantly reduce the tree's stability.

If you're unsure whether trunk damage is serious, it's always safer to have the tree professionally assessed.

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Canopy Warning Signs

The canopy often provides the first visible clues that it is becoming unhealthy.

Look for:

Large dead branches
Hanging or broken limbs
Crossing branches rubbing together
Sections of the crown with little or no foliage
Dead branches scattered throughout the canopy
Trees failing to produce leaves during the growing season

One particularly dangerous issue is a "widowmaker"—a large broken branch that becomes trapped high in the canopy. These branches can fall unexpectedly and should only be removed by trained professionals.

Is A Leaning Tree Dangerous?

Not all leaning trees are unsafe. Many trees naturally grow with a slight lean and remain perfectly stable for decades.

However, a plant that suddenly begins leaning or leans by more than approximately 15 degrees should be investigated.

Warning signs include:

A noticeable increase in lean
Raised soil opposite the lean
Exposed roots
Fresh cracks in the ground
Movement during windy weather

These signs can indicate that the root system has begun to fail and that it may be at risk of falling.

What Causes Trees To Become Dangerous?

Trees can become unsafe for many different reasons, some developing slowly over many years while others occur suddenly following severe weather.

Disease And Decay

Fungal infections and internal decay gradually weaken it from the inside. Unfortunately, much of this damage cannot be seen without a professional inspection.

Storm Damage

High winds, heavy rain, and snow can crack branches, split trunks, or loosen root systems, even when the tree appears healthy from a distance.

Root Damage

Building work, excavations, flooding, and soil compaction can damage roots, reducing the tree's ability to remain securely anchored.

Poor Previous Work

Incorrect pruning or topping can weaken the structure of a tree, encouraging unstable regrowth and increasing the likelihood of branch failure.

Professional pruning carried out to recognised arboricultural standards helps maintain the tree's long-term health and safety.

What Should You Do If You Think A Tree Is Dangerous?

If you suspect it may be unsafe, avoid trying to remove branches or carry out repairs yourself.

Instead:

Keep people away from the affected area.
Avoid parking vehicles beneath the tree.
Monitor any changes after severe weather.
Contact a qualified tree surgeon for an inspection.
Arrange emergency work if the tree presents an immediate risk.

Acting early often allows problems to be addressed before they become emergencies.

When To Call A Professional Tree Surgeon

You should contact a professional tree surgeon if:

The plant has developed a sudden lean.
Large dead branches are present.
Mushrooms or fungal brackets appear around the base.
The trunk has deep cracks or large cavities.
Branches overhang your property or public highways.
Storm damage has occurred.
You are unsure whether it is safe.

At M.A.C Tree Care, our NPTC-qualified tree surgeons have more than 20 years of arboricultural experience. We carry £5 million public liability insurance and provide professional inspections, surveys, pruning, and safe removal throughout Sidcup and the surrounding areas.

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Frequently Asked Questions

Get Expert Advice About The Signs A Tree Is Dangerous

If you've noticed cracks in the trunk, fungal growth, dead branches, or your plant has started leaning unexpectedly, don't ignore the warning signs. M.A.C Tree Care provides professional inspections, surveys, and safe removals across Sidcup, Kent, and the surrounding areas.

Our experienced, NPTC-qualified team can assess your tree, explain the level of risk, and recommend the safest course of action before the problem becomes an emergency.

Areas We Cover

Borough of Bexley

Thamesmead, Abbey Wood, Belvedere, Erith, Northumberland Heath, East Wickham, Welling, Bexleyheath, Barnehurst, Crayford, Blackfen, Blendon, Bridgen, Bexley, Halfway Street, Longlands, North Cray, Sidcup, and Foots Cray.

Kent

Borough of Bromley

Sevenoaks

Borough of Greenwich

London - for larger projects, we cover the wider areas of London

Working Hours

Monday 7 am–5 pm
Tuesday 7 am–5 pm
Wednesday 7 am–5 pm
Thursday 7 am–5 pm

Friday 7 am-5 pm

Saturday 7 am–5 pm

Sunday Closed