Signs an Exeter tree may be unsafe

A tree that looks healthy from the pavement can still drop a limb on a car, a fence or a child, and most failures give some warning before they happen. Owners in Exeter who learn the common defects can spot the danger early, decide whether the tree needs a professional inspection and avoid the situation in which a storm turns a neglected problem into a claim. The signs below are not a substitute for an inspection, but they are the points at which an owner should stop assuming the tree is safe.

Cracks, decay and fungal brackets

Cracks are the first thing to look for. A split running along the trunk or through a major union, particularly where two stems meet at a narrow angle, weakens the structure, and the risk rises when the crack opens or closes with the wind. Cracks in the bark can be superficial, but a crack that goes into the wood and runs vertically is a serious concern, and it should be examined by someone who can see inside the stem.

Fungal brackets are the most reliable indicator of internal decay. Bracket-shaped or bulbous fruiting bodies at the base of the trunk, on roots or along a major limb usually mean that the wood beneath has been colonised by a fungus that breaks down the structural timber. Not every bracket means the tree is unsafe, because some fungi live on dead wood without much effect on the living tissue. The presence of a bracket should, however, prompt an inspection, because the decay behind it may be far more extensive than the surface suggests.

Soft or spongy wood, hollow sounds when the trunk is tapped and cavities that expose the heartwood are further signs of decay. An owner should not try to test the wood with a tool or a hammer, which can cause damage, but should note any change in the feel or sound of the trunk and report it.

Lean and root plate movement

A tree that has begun to lean, particularly one that has leaned further in recent months, may be failing at the root plate. Look at the ground around the base for cracks or heaving, for soil that is raised on one side and sunken on the other, and for roots that have lifted out of the ground. These signs suggest that the tree is moving as a whole, and that the anchor on one side is no longer holding.

A lean is not always a sign of danger. Many trees grow at an angle to reach light, and the lean may have been stable for decades. The concern is change: a tree that was upright last year and is now clearly leaning, or a lean that has shifted since the last storm, needs prompt assessment. Work that disturbs the root zone, such as trenching, paving or heavy compaction from vehicles, can also cause the root plate to fail, and any such work near a tree should be planned with that in mind.

Dead wood and storm damage

Dead branches are among the most common hazards. A limb with no leaves in the growing season, bark that has fallen away, or wood that snaps easily when lifted all point to dead wood. Dead wood in the crown can fall without warning, and in a mature tree the largest pieces can be heavy enough to cause serious injury. An owner who sees dead wood over a path, car park or play area should treat it as urgent.

Storm damage calls for prompt attention. A tree that has been split, uprooted in part or left with hanging branches after a gale is at increased risk, even if it appears to be standing firm. Trees can be weakened by storms without showing obvious damage, and a second storm can bring down a limb that the first one loosened. The Met Office's UK weather warnings are a useful source of information about wind events, and an owner who expects a storm can check the trees near high-risk areas before it arrives.

Ash dieback is a specific risk for ash trees. The Forest Research programme on ash dieback impact examines how the disease affects woodland and species, and the disease weakens the crown and the stem in ways that can make affected trees hazardous. Owners with ash trees should ask a qualified person to assess them, rather than relying on a general look from the ground.

Duty of care for tree owners

Owners have a general duty to take reasonable care that their trees do not cause harm to people or property. The duty is not an assurance that no tree will ever fall, but it does require owners to act when they know, or ought to know, that a tree presents a risk. A tree with visible decay, a serious lean or a large dead limb over a public path is the sort of case where the owner is expected to act promptly. Owners who let a property should also consider how the tree is managed between tenancies, since the landlord's arrangements for inspection are often what a later claim turns on.

The duty applies in gardens, on commercial sites and in public places alike. A tree that overhangs a neighbour's land creates a relationship between the two owners, and a tree on a council verge or a school field is the responsibility of the body that controls the land. The Health and Safety Executive's tree work pages explain the wider safety framework for work on trees, and they are a useful reference for commercial owners who are arranging inspections and remedial work.

Protected trees add another layer. Work to make a protected tree safe may be exempt from the normal consent requirement where there is an immediate risk, but the exemption is narrow, and the owner should check with the council before acting unless the danger is obvious and urgent. The guidance on tree preservation orders and trees in conservation areas sets out the exceptions, and the owner should keep a record of the assessment that led to any emergency work. Even when the exception applies, written notice must reach the council as soon as practicable after the work becomes necessary, and a tree that is dead but not an immediate danger needs five working days' written notice before work starts.

Recording what you see helps. Keep a dated set of photographs of the tree from the same viewpoint, so that a change in lean or a new crack can be seen over time. A note of the weather before and after a storm is also useful. A surveyor who is shown a sequence of photographs is better placed to judge whether a defect is developing or has been stable for years.

When to call an expert

An owner who sees any of the signs above should arrange an inspection by a suitably qualified person. The Forest Research tree health diagnostic and advisory service is one route for identifying disease and decay, and a qualified arborist can assess the structure of the tree and recommend a remedy. The inspection should produce a written report that describes the defect, the risk and the recommended action, so that the owner can make a decision and keep the record.

For a larger tree or a group of trees, the commercial tree service includes inspections as part of a wider programme, and the inspection service covers the assessment of individual trees. Owners who are not sure whether a problem is urgent can send a quote request describing the symptoms, the location of the tree and the targets beneath it, such as a driveway, a path or a neighbour's property.

Once a defect has been found, the timing of the response matters as much as the choice of method. A tree with a split union or a fresh fungal bracket is not made safer by waiting for the next inspection slot, and an owner who has a written report in hand can act on it at once. The guide on felling licence thresholds explains when a licence may be needed if the tree has to come down, and the guide on talking to neighbours covers the conversation to have if the tree overhangs a shared boundary.

Sources and further reading

1. UK weather warnings (Met Office)
2. Ash dieback impact (Forest Research)
3. Tree work (Health and Safety Executive)
4. Tree Preservation Orders and trees in conservation areas (GOV.UK)
5. Tree health diagnostic and advisory service (Forest Research)