Trees are a wonderful asset to any Perth property. They provide shade during our scorching summers, privacy from the street, habitat for native wildlife, and genuine kerb appeal that can add thousands of dollars to a home’s value. But trees are also living things — and like all living things, they age, fall ill, sustain injuries, and eventually die.
The problem is that a dangerous tree rarely announces itself clearly. It does not come with a warning label. The signs of structural failure, disease, or decay can be subtle, hidden inside the trunk, or easy to dismiss as normal wear and tear — right up until the moment a major limb comes down on your car, your fence, or worse, your roof.
Every year across Perth, preventable tree accidents damage properties and injure people. The vast majority of these incidents involve trees that were showing warning signs long before they failed. Knowing what to look for could save you a significant insurance claim, an expensive repair bill, or something far more serious.
This guide covers the key warning signs that a tree may be dangerous or in need of professional attention, and explains when it is time to call in a certified arborist.
Why Trees Fail — And Why It Matters
Before diving into the warning signs, it is worth understanding why trees fail structurally. Healthy trees are remarkably strong — their wood is designed to flex in wind rather than snap, and a well-structured canopy distributes load evenly across the trunk and root system. But a range of factors can compromise this structural integrity over time.
The most common causes of tree failure in Perth include internal decay caused by fungal infection, storm damage that creates entry points for disease, poor branch attachment that develops weak unions as the tree grows, root damage from construction or soil compaction, prolonged drought stress, and the natural decline that comes with old age. Perth’s specific climate — long dry summers, periodic heavy storms, and sandy soils that don’t anchor roots as firmly as clay — creates its own set of risk factors that local homeowners need to be aware of.
The tricky part is that many of these problems are not visible from the outside. A tree can look perfectly healthy from the street while being hollow or structurally compromised at its core. This is why a professional arborist assessment is so valuable — but there are also plenty of visible warning signs that any homeowner can learn to spot.
Warning Sign #1: Dead or Hanging Branches
This is one of the most obvious and dangerous signs to look for. Dead branches — sometimes called “widow makers” — are branches that have died but remain in the canopy, held in place by surrounding branches or simply by gravity. They are brittle, unpredictable, and can fall without any warning, even on a calm day.
Look for branches that have no leaves during the growing season, that have bark peeling away in strips, or that appear grey and dry compared to the healthy branches around them. Also watch for hanging branches — those that have already partially broken and are resting on other branches. These are particularly dangerous because they can be dislodged suddenly by wind, rain, or even a bird landing on them.
A few dead branches in an otherwise healthy tree is not necessarily a crisis, but a large number of dead branches throughout the canopy — a phenomenon arborists call “crown dieback” — can indicate serious underlying problems with the tree’s health.
Warning Sign #2: Cracks or Splits in the Trunk or Major Branches
Vertical or horizontal cracks in a tree’s trunk or major limbs are a serious red flag. These can indicate internal decay, frost crack (less common in Perth but not unheard of), or structural failure that is already in progress. Co-dominant stems — where a tree has grown two or more main trunks of roughly equal size from a single point — are particularly prone to splitting, especially if the union between them is tight or V-shaped rather than broad and U-shaped.
Run your eye along the main trunk and the primary branches. Any visible crack, split, or wound that has not healed cleanly over with new bark deserves a closer look from a professional.
Warning Sign #3: Fungal Growth at the Base or on the Trunk
The appearance of mushrooms, shelf fungi (also called bracket fungi), or any other fungal growth at the base of a tree or on its trunk is one of the most serious warning signs a homeowner can observe. Fungi of this type almost always indicate advanced internal decay. By the time fungal fruiting bodies are visible on the outside of the tree, the decay inside is typically already well progressed.
A tree with significant internal decay may have very little structural wood left holding it upright. It can look perfectly normal from a distance — full canopy, green leaves, upright trunk — and yet be at serious risk of sudden, catastrophic failure.
If you see any fungal growth on or around your trees, do not delay. Call a certified arborist for an assessment as soon as possible.
Warning Sign #4: A Leaning Trunk
Not all leaning trees are dangerous — many trees develop a natural lean as they grow toward light, and this lean is well-accommodated by their root system. However, a lean that has developed suddenly, noticeably increased over recent months, or that is accompanied by other warning signs is cause for serious concern.
A sudden lean is particularly alarming. If a tree that was previously upright has developed a lean following a storm, heavy rain, or a period of dry weather, it may indicate that the root system has partially failed. Look at the base of the tree for signs of soil heaving or cracking on the side opposite to the lean — this can indicate that roots are beginning to pull out of the ground.
Warning Sign #5: Root Damage or Soil Disturbance
The roots of a tree are its anchor and its lifeline, but they are also the part of the tree that is most often damaged without the homeowner realising. Construction work, trenching for pipes or cables, driveway or paving installations, and even heavy vehicle traffic over the root zone can all cause serious root damage that only manifests in the tree’s health and stability months or years later.
Signs of root problems to watch for include: soil lifting or cracking near the base of the tree, exposed roots that appear damaged or rotting, a general thinning of the canopy without obvious explanation, or a tree that is growing in an area where significant earthworks have taken place in recent years.
Perth’s sandy soils are also worth noting — they provide less root anchorage than heavier soils, which means trees in sandy ground can be more vulnerable to windthrow, particularly when the soil is saturated after heavy rain.
Warning Sign #6: Cavities or Hollows in the Trunk
A visible hollow or cavity in the trunk of a tree is a sign that decay has removed wood from inside the tree. Small hollows can be present in otherwise healthy trees and may even provide habitat for native wildlife, but large cavities — particularly those near the base of the tree or at branch unions — significantly reduce the structural strength of the tree.
Assess not just the size of the cavity but also its location. A cavity at the base of the trunk is far more serious than one higher up, because it compromises the part of the tree bearing the greatest structural load.
Warning Sign #7: Bark Problems and Cankers
Healthy tree bark is generally firm, consistent in colour, and well-attached to the wood beneath it. Warning signs in the bark to look for include: large areas where bark is missing or has fallen away; discoloured, sunken, or swollen patches (these can indicate cankers, which are areas of dead bark caused by fungal or bacterial infection); oozing sap or liquid from wounds; and bark that sounds hollow when tapped.
These signs can indicate disease, insect infestation, or environmental stress — all of which can weaken a tree’s structural integrity over time if left unaddressed.
Warning Sign #8: Proximity to Structures, Power Lines, and People
Even a perfectly healthy tree can warrant removal or significant pruning if its location creates unacceptable risk. A large tree growing directly over your home, a tree whose canopy is encroaching on power lines, or a tree next to a frequently-used area like a children’s playground or a driveway all deserve careful consideration — regardless of whether the tree currently shows signs of disease or structural weakness.
The larger a tree grows in a constrained or high-traffic location, the greater the potential consequences of any failure. In these situations, proactive management — professional pruning to reduce the crown, or removal before failure occurs — is almost always the smarter and more cost-effective choice.
When to Call an Arborist Immediately
While all of the above signs are worth monitoring, certain situations call for urgent professional attention. Contact a certified arborist without delay if:
- A large branch has partially broken and is hanging in the canopy
- The tree has developed a sudden or worsening lean after a storm
- You can see fungal growth at the base of the tree
- A significant crack has appeared in the trunk or at a major branch union
- The tree is near your home and the canopy is showing widespread dieback
- Roots appear to be pulling out of the ground
In situations where you believe there is an immediate and serious risk to life or property, contact your local council as well — they have powers to require urgent action when a tree poses a genuine public safety risk.
What Happens During a Professional Tree Assessment?
When you call AB Trees for an assessment, our qualified arborists will carry out a thorough visual inspection of the tree — examining the canopy, trunk, bark, root zone, and surrounding environment. We will look for all of the warning signs described above, as well as more subtle indicators that require trained eyes to identify.
Where internal decay is suspected, we can recommend further investigation. We will provide you with a clear, honest written assessment of the tree’s condition, the level of risk it presents, and the options available to you — whether that is targeted pruning, crown reduction, or full removal.
We never recommend removal unless it is genuinely the right outcome for the tree and your property. Our job is to give you honest, expert advice — not to sell you unnecessary work.
Don’t Wait for the Tree to Tell You
The single biggest mistake Perth homeowners make with potentially dangerous trees is waiting too long. Trees do not fail on schedule. A tree that has been quietly decaying for years can come down in a single storm gust — or on a still, sunny afternoon with no warning at all.
The cost of a professional arborist inspection is minimal compared to the cost of repairing storm or fall damage to your home, fencing, or vehicles. And it is nothing compared to the potential human cost of a large branch or tree falling in the wrong place at the wrong time.
If you have a tree on your property — or a neighbor’s tree near your property — that you are uncertain about, the best time to have it assessed was last year. The second best time is today.
Get a Free Tree Assessment in Perth
At AB Trees, our fully qualified arborists serve the entire Perth metropolitan area, north and south of the river. We offer free, no-obligation quotes and written assessments, and we approach every job with our strict no-mess, no-damage policy.
Whether you need a single tree assessed, a dangerous limb removed urgently, or a full tree removal with stump grinding, we have the equipment, experience, and expertise to do the job safely and properly.
Call Ben on 0424 150 899 or visit us at abtrees.com.au to request your free quote today. Don’t leave a potentially dangerous tree to chance — let Perth’s trusted arborists give you peace of mind.
