Trees are remarkably resilient, but they can and do fail. When a large branch or whole tree comes down, the damage can be catastrophic — to property, to vehicles, and occasionally to people. The good news is that most tree failures don’t happen without warning. Here are seven signs that your tree may be in trouble.
The first and most obvious sign is dead branches in the canopy. Dead branches (also called deadwood) are dry, brittle, and have no leaves in summer. They can fall without warning, even in calm weather, as the wood decays and loses its structural strength. A few small dead twigs are normal, but large dead branches — anything over about 50 mm in diameter — should be removed. If a significant proportion of the canopy is dead, the tree itself may be in decline.
Second, look for fungal fruiting bodies on or around the tree. Bracket fungi growing from the trunk or major limbs are often a sign of internal decay. Common species to watch for include Ganoderma (a flat, brown bracket that appears at the base), Inonotus hispidus (a large, rusty-brown bracket on broadleaves), and honey fungus (Armillaria) which produces clusters of honey-coloured toadstools around the base in autumn. Not all fungi are harmful, but any significant fungal growth should be assessed by an arborist.
Third, check for cracks and splits in the trunk or major branches. Vertical cracks in the trunk can indicate internal stress, and horizontal cracks at branch unions can signal a weak attachment that’s starting to fail. Included bark — where bark is trapped in the junction between two stems or branches — creates a structurally weak point that is a common cause of branch failure. V-shaped unions are generally weaker than U-shaped ones.
Fourth, a sudden or progressive lean. All trees lean to some degree, often towards the light, and a tree that has always leaned is not necessarily a problem. But a tree that has recently started to lean, or one that leans significantly more after a storm, may have root failure. Look at the ground on the opposite side from the lean — if you can see the soil lifting or cracking, the roots may be pulling out of the ground.
Fifth, root damage or disturbance. Building work, new driveways, changes in ground level, or even prolonged waterlogging can damage tree roots and compromise the tree’s stability. Root damage may not become apparent for several years, but signs include a thinning canopy, dieback in the crown, and mushrooms or toadstools appearing around the base. If you’ve had construction work near a large tree in the last few years, it’s worth having the tree assessed.
Sixth, cavities in the trunk. A cavity isn’t automatically a death sentence — many hollow trees remain structurally sound because the outer shell of living wood is doing most of the structural work. But large cavities, especially those at the base of the tree, can significantly reduce the tree’s ability to withstand wind. The extent of the decay matters more than the size of the opening, so a professional assessment with specialist tools may be needed.
Seventh, a significant change in the canopy. If a tree that has always had a full, healthy canopy suddenly shows sparse foliage, yellowing leaves out of season, or dieback in the tips, something is wrong underground or inside the trunk. This can be caused by root disease, vascular disease, drought stress, or soil compaction. While not always an immediate danger, a declining tree is more likely to fail over time and should be monitored.
If you notice any of these signs, the best course of action is to have the tree inspected by a qualified arborist. We carry out tree safety inspections across Sussex, providing a written report with recommendations. In most cases, the tree can be made safe through pruning, deadwood removal, or crown reduction. Where a tree needs to be removed, we’ll explain why and handle any permissions that are needed.
It’s worth noting that a duty of care exists for tree owners. Under common law, you have a responsibility to take reasonable steps to ensure that trees on your land don’t cause harm to others. Regular visual checks and acting on any concerns is usually sufficient to meet this duty. If you’re not sure about a tree, get it looked at — it’s far cheaper than dealing with the consequences of a failure.
