Signs a Tree Is Dying, and When It Needs to Come Down

Two different questions, and people usually ask the wrong one. A tree can be very sick and stay standing for a decade. A tree can look fine and be one nor'easter from your roof. Here's how to check both without leaving the ground.

Part one: is it dying?

The scratch test (do this first, it takes five seconds)

Scratch a little bark off a twig with your thumbnail. Green and moist underneath means living tissue. Brown, dry, and brittle means that limb's dead. Try it in a few spots around the tree: low, high, different sides. If everything you test is brown in late spring, when it should be leafed out, the tree's done.

Canopy dieback from the top down

Healthy trees fill out evenly. A tree in decline usually dies from the outer edges and the top inward, so you'll see bare "stag horn" branches poking up above the leafy part of the crown. Thinning that gets worse year over year is the pattern to watch. One bare limb is normal. A crown that's 30% bare and was 15% last year isn't.

Leaves that tell on the tree

Leafing out late in spring, leaves smaller than they used to be, yellowing while the neighbors' trees are green, or early leaf drop two years running. One odd year after a drought summer is normal here. Two in a row is the tree telling you something.

Bark and trunk

Big patches of missing bark, deep vertical cracks, or bark that sounds hollow when you knock on it. Sawdust-like frass at the base means borers are already inside. On our older maples, a cavity where a big limb came off years ago and never closed over is a slow structural problem.

Mushrooms and conks

This is the one homeowners underrate most. Shelf fungi or mushrooms growing on the trunk, at the base, or on the surface roots mean decay is already established in the wood, and by the time it fruits on the outside there's usually a lot of rot inside. Most people spot them for the first time while raking: a row of little shelves along the root flare that weren't there last fall. A big tree with conks at the base near a house deserves a professional look sooner rather than later, even if the canopy still looks healthy.

Part two: is it dangerous? (a different question)

Structure, not health, is what puts a tree through your roof. These are the ones that make us say "this month" instead of "keep an eye on it":

• A new lean, or soil heaving on one side. If the ground at the base is cracked or mounded opposite the lean, the root plate is lifting. That's a tree in the process of falling over. Norway maples on our saturated sandy soil do exactly this.
• A split or included bark at a major fork. Two big stems meeting in a tight V with bark pinched between them will split eventually, usually in wind, usually all the way down. Bradford and Callery pears are the poster children. They tear apart around fifteen to twenty years old, almost on schedule.
• Hanging or cracked limbs left over from the last storm. A limb caught in the canopy waiting for the next gust picks its own time to land. These come down first on our storm calls.
• Large dead limbs over something that matters. A dead limb over the lawn is a maintenance item. The same limb over the driveway, the deck, or the sidewalk is a liability.
• Decay at the base of a big tree near the house. Cavities, soft wood you can push a screwdriver into, conks. The trunk is the one part of a tree that gets no second chances.

What this looks like around here

Most of the South Shore was planted in the two decades after the war, so the whole area is hitting tree old age at once. The failures we get called about most:

Norway maples: shallow root plates, prone to heaving and tipping in saturated ground, and they lift the sidewalk on the way. Silver maples: fast-growing, brittle, and shedding big limbs for thirty years now. Bradford and Callery pears: the 1980s default planting, splitting at the trunk on schedule. London planes: a lot of them took a salt hit after Sandy in 2012 and have been declining slowly ever since, so the dieback you're seeing in those is often a decade-old injury still playing out. And healthy pin oaks and red oaks that aren't dying at all. They just outgrew a 40-by-100 lot, which is a different conversation.

What to do about it

Not everything on this page ends in removal, and we won't pretend it does. Deadwood in an otherwise sound tree is a pruning job. A heavy limb over the roof can often be reduced instead of the whole tree coming down. Where it does have to come out (dead, split, leaning, or decayed at the base), that's removal, and doing it on a scheduled Tuesday costs far less than doing it at 2 a.m. after a nor'easter with the tree already on the house.

Inside the Village of Valley Stream, one useful note: Chapter 90 lets the Village order a dead or dangerous tree removed, and a permit for taking down a hazardous tree is a formality, not a fight. Photos documenting the decline help.

Not sure which category your tree is in? A look costs nothing, and it often ends with "prune these three limbs" rather than "take it down": (516) 619-3667.