Most trees tell you they are failing long before they fall. Here's what to look for from the ground, and which signs mean removal versus pruning.
Walk around the tree in summer. If more than about half the crown is dead — bare branches while neighbors leaf out — the tree is in terminal decline. In Connecticut, the most common cause is emerald ash borer on ash: bark falling off in patches, D-shaped exit holes, and woodpecker damage are the tells. A dead crown does not recover, and dead limbs shed unpredictably.
Some trees grow with a natural lean and live with it for decades. The danger sign is a lean that increased — after a storm, or gradually over a season — especially with soil heaving or cracking on the opposite side. That means roots are failing. Photograph the lean against a fixed reference (a fence post, a house corner) and compare over weeks; a moving lean is an emergency assessment.
A vertical crack running down the trunk, especially one that opens and closes with wind, means the trunk's structure is splitting. Cracks through a fork where two stems meet are the worst — that union is already the tree's weakest point. A cracked trunk cannot be pruned back to safety.
A hollow trunk is not automatically a removal — many old oaks live for decades with cavities. The line is how much sound wood remains around the cavity and whether the cavity connects to a crack or a weak union. Mushrooms or fungal fruiting bodies on the trunk (especially at the base) signal internal decay that you cannot see from outside. An arborist with a sounding mallet or resistograph can measure what remains.
Look at where major limbs meet the trunk. A U-shaped union with bark rolling into the joint is strong. A tight V-shaped union with bark trapped inside — "included bark" — is a weak joint that splits under load. V-unions over a roof or driveway are the classic failure point in wet snow.
Roots fail quietly. Trenching for a driveway or utility, grade changes that bury or expose roots, and construction compaction all kill roots over two to five years. The visible signs: a crown that thins year over year after nearby construction, mushrooms at the base, or soil lifting on one side. A tree that thinned after a neighbor's project is a hazard candidate even if the trunk looks clean.
When in doubt, get a written assessment. A crew that explains which category your tree falls in — and why — is a crew you can trust with the removal if one is needed.
Two minutes. Matched with a local tree service. Free written estimate, no obligation.