Signs Your Tree Is Failing (and What They Actually Mean)

Not everything alarming about a tree is a problem, and not every problem looks alarming. This is a guide to telling them apart before you spend money either way.

Signs that warrant attention now

These indicate potential structural failure. If you see one on a tree that could hit something, get it assessed rather than watching it.

Fungal fruiting bodies at the base or on the trunk

Brackets, conks or mushrooms growing from the trunk or root collar generally mean decay is already well established inside the tree. The visible fruiting body is the reproductive structure — the fungus has typically been consuming wood internally for years before it appears.

This matters more than almost any other single sign, because decay in the butt and root zone attacks exactly the wood that holds the tree upright, and it is invisible from outside.

A crack running vertically down the trunk

Especially where it runs into a union or the root collar. Vertical cracks can indicate the trunk is separating under load.

Included bark in a major union

Where two stems meet in a tight V rather than a rounded U, bark can become trapped between them. The union looks solid but has no structural wood connecting it. These fail suddenly, usually in wind, and often on trees that appeared perfectly healthy.

Recent lean, or soil movement at the base

A tree that has always leaned is usually fine — it has grown reaction wood to compensate. A tree that has recently changed its lean is a different matter. Look for cracked or heaved soil on the opposite side of the lean, or exposed roots lifting. That indicates root plate failure in progress.

Large deadwood in the canopy

Individual dead branches are normal. Multiple large dead limbs, particularly if the deadwood is concentrated in the upper canopy, suggest something systemic.

Hollows with associated decay

Hollows alone are not automatically a problem — many healthy trees have them, and they carry real habitat value. What matters is the amount of sound wood remaining around the hollow, which is a measurement rather than a guess.

Signs of decline worth investigating

These are health rather than immediate structural concerns, and most are more reversible than people assume — if the cause is correctly identified.

Canopy thinning or dieback from the top

Progressive thinning, smaller leaves each season, or dieback starting at the outer and upper canopy usually indicates the tree cannot supply what it needs to. That is nearly always a root or vascular problem, not a canopy one.

Epicormic growth on trunk and major limbs

Clusters of shoots erupting directly from the trunk are a stress response — the tree deploying dormant buds because its normal canopy is failing. Treat it as a symptom, not a recovery.

Off-season leaf drop or early autumn colour

A tree shedding leaves out of season is shedding load it cannot support.

Bleeding, oozing or staining on the trunk

Dark weeping patches can indicate bacterial infection or internal decay reaching the surface.

Things that look worse than they are

Worth knowing, because they generate a lot of unnecessary worry and unnecessary quotes.

Lichen and moss on bark. Harmless. Lichen is not parasitic and does not feed on the tree. It is often more visible on a thinning tree simply because more light reaches the bark, which reverses the causation people assume.

Sooty mould. Black coating on leaves, usually growing on honeydew from sap-sucking insects. It is unsightly and indicates a pest issue worth addressing, but is not itself killing the tree.

Surface roots. Normal for many species, particularly figs and eucalypts, and especially in compacted urban soil where roots are pushed toward the surface seeking oxygen. Annoying to mow around; not a health problem.

Seasonal leaf drop. Some species Brisbane residents assume are evergreen are not.

A long-standing lean. As above — established leans with good reaction wood are usually stable. It is change that matters.

The part most people miss

Here is the pattern I see repeatedly.

Someone notices canopy decline, calls someone, and gets fertiliser, or a treatment, or a recommendation to remove. Sometimes the tree improves briefly. Usually it does not, and the money is gone.

The reason is that most urban tree decline in Brisbane originates below ground, and the canopy is where you notice it rather than where it starts. The common causes:

• Compaction from construction traffic, parking, or years of foot traffic — collapsing the pore space roots need for oxygen
• Fill over the root zone — a raised garden bed or regraded lawn suffocating roots under 300mm of soil
• Root severance from trenching for services, plumbing or a fence line
• A buried root collar — turf and mulch heaped against the trunk over years, causing collar rot
• Altered drainage — a new driveway, extension or retaining wall redirecting water

None of these are visible from the canopy. All of them present as canopy decline. And treating the canopy — fertilising a tree whose roots cannot breathe — reliably fails, because the diagnosis was never made.

This is the distinction between a report that describes a condition and one that explains it. Fertiliser does not fix compaction. Only correctly identifying the compaction does.

When to get it assessed

Straight away if you see fungal brackets at the base, a new or worsening lean with soil disturbance, a vertical trunk crack, or large deadwood over something that matters.

Soon if the canopy is progressively thinning across seasons, or if you have done building work near the tree in the last few years and it has not looked right since.

Before you spend money on treatment if a tree is declining and you have not established why. Treating an unidentified cause is the most reliable way to waste money on a tree.

Probably not at all if what you are seeing is lichen, surface roots, sooty mould, or a lean the tree has had since you moved in.

If you are unsure which category you are in, a photo and a description usually settles it — often without needing a site visit at all.