Here’s the thing about dying trees: they rarely announce it. A tree that is actively declining can spend years looking mostly fine to a homeowner walking the yard every weekend. The changes are subtle. A canopy that is 10% thinner than last year. Bark that used to be tight and is now loose at the base. A few more dead twigs on the driveway after each windstorm. Most people notice when a tree is dead. The useful skill is noticing when a tree is dying — because that is when the decisions still matter.
These are the ten signs worth checking on any mature tree in Central PA. None of them require climbing. All of them are visible from the ground.
1. The canopy is thinner than it was two years ago
This is the single most diagnostic sign of general decline. If the crown used to block the sky and now shows patches of light through it, the tree is losing leaf density. Penn State Extension’s guidance on landscape tree problems identifies progressive canopy thinning as the first visible symptom of root decline, vascular damage, or sustained stress. One thin year can be weather. Two thin years is a pattern.
2. Dieback starts at the top
When a tree’s water supply is compromised — damaged roots, girdling root, vascular disease — the highest branches die first because water has to climb the farthest to reach them. Dead tips at the top of the crown, progressing downward season after season, are a classic sign that the tree is losing its ability to move water.
3. Leaves are smaller than normal
A tree under chronic stress produces smaller leaves. Less photosynthesis, less food, less growth the next year — the feedback loop tightens. Compare the leaves to the same species growing in better conditions nearby. If the leaves are noticeably smaller, the tree is rationing.
4. Early fall color — ahead of everything else
A tree that turns yellow or red two to three weeks before the same species across the street is not ahead of the season. It is behind on resources. Early fall color is a stress flag, not a display.
5. Bark falling off in sheets or plates
Bark is the tree’s skin. When large sections of bark peel away on a deciduous tree — not the normal thin sheddding that birch or sycamore do — it usually means the cambium underneath has died. That section of the trunk is no longer functioning. The USDA Forest Service Tree Owner’s Manual describes bark loss as one of the late-stage indicators of serious decline.
6. Fungal conks or mushrooms growing from the trunk or root flare
Mushrooms and bracket fungi on a living tree are not cosmetic. They are the fruiting bodies of wood-decay fungi that have already colonized the interior. By the time the conk is visible on the outside, the internal wood has been compromised for years. A tree with conks at the base is a tree with a structural question mark.
7. Cracks or splits in the trunk
A vertical crack in the main trunk — not a shallow surface check but a deep split — is a structural failure waiting for a load event. Cracks often appear on the side of the trunk that faces the prevailing wind or the direction of lean. Two cracks on opposite sides of the trunk are especially concerning.
8. The root flare is missing
A healthy tree’s trunk widens at the base where the structural roots begin. If the trunk goes straight into the ground like a fence post — no flare, no visible roots — then either fill soil has been added over the root zone, or the tree was planted too deep, or a girdling root is compressing the trunk. All three conditions lead to decline. ISA’s TreesAreGood homeowner materials describe the visible root flare as one of the first things to check during a tree assessment.
9. Excessive suckering at the base
A flush of small shoots growing from the base of the trunk or from surface roots is often a last-effort response. The tree is throwing out emergency growth because the main canopy is failing. A few root suckers are normal on some species. A dense ring of suckers around the base of a tree that didn’t used to produce them is a stress signal.
10. The tree leans and it didn’t lean before
Trees that have always grown at an angle are usually fine — they formed their wood to handle the load. A tree that has recently started leaning — especially if the soil on the uphill side is cracking or heaving — is a different situation entirely. New lean means root failure on one side. That is a hazardous tree conversation.
What to do with the list
Walk the property. Check every mature tree against these ten signs. Any tree that hits three or more is worth a closer look. A tree health assessment from a PA-licensed tree service can determine whether the tree is saveable, manageable, or a removal candidate — and if it is a removal candidate, whether the timeline is “this season” or “soon.”
For properties in Centre County and the surrounding region, call (814) 553-0303. Arbor Pro’s Tree Service operates under PA Contractor License PA079160.