7 Signs a Tree Is Dangerous and May Need Removal

Most trees are not dangerous, and most never will be. But a tree that is failing usually gives warning signs first - if you know what to look for. On the North Shore, where mature trees stand close to homes, driveways, and sidewalks, learning to read those signs can be the difference between a planned removal and a storm-night emergency. Here are seven of the clearest warning signs, what each one means, and which ones mean you should stop watching and call someone.

1. A lean that is new or getting worse

Many trees lean a little and have leaned that way for decades - that is usually fine. What matters is a lean that is new, or visibly worsening, especially if you see cracked or heaving soil on one side of the base. That raised, mounding soil is a sign the root plate is starting to lift - the tree is beginning to tip. A sudden lean after a storm is a red flag that the roots may be failing. This one moves toward the "call now" category, particularly over a target.

2. Dead limbs in the canopy

Large dead branches - bare, no leaves in summer, bark peeling - are a hazard on their own even if the rest of the tree is healthy. Deadwood is brittle and drops without warning, and a big dead limb over a driveway or walkway is a real risk. Scattered small deadwood is normal in any mature tree and is routine pruning work. A canopy that is mostly bare, though, points to a dying tree - see is my tree dead.

3. Cracks and cavities in the trunk

A deep vertical crack running up the trunk, or a large cavity or hollow, can mean the tree's main support is compromised. Not every cavity is fatal - trees compartmentalize decay and many live for years with a hollow - but a large one, especially paired with other signs or located under a heavy lean, is worth an expert look. A crack that runs deep and appears to be spreading is more urgent than an old, sealed-over wound.

4. Fungus at the base or on the trunk

Mushrooms or shelf fungus (conks) growing at the base of the trunk or on the roots are one of the more serious signs, because they often indicate root or trunk decay you cannot see from the outside. The tree may still be standing and leafing out fine, but the wood that holds it up could be rotting. Fungus at the base of a large tree over a target is a strong reason to get it assessed rather than to wait.

5. Root problems and soil heave

The roots hold the whole tree up, and they are the part you cannot see. Warning signs include soil lifting or cracking on one side, severed roots from a recent driveway, patio, or excavation job, and a tree that has been through nearby construction. Root damage can quietly destabilize a tree that looks perfectly healthy above ground - which is why a tree that survived a construction project deserves a look a year or two later.

6. A weak fork or co-dominant stems

Some trees split into two large trunks (stems) that grow up side by side. When they meet in a tight V-shape with bark pinched between them (called included bark), that union is weak and prone to splitting - often in a storm, often taking half the tree with it. A big co-dominant stem hanging over the house is a classic candidate for either removal or a support cable, depending on the tree.

7. Storm damage and hanging limbs

After a storm, look up. Broken limbs still hanging in the canopy ("widowmakers"), a freshly split fork, or a partially uprooted tree are immediate hazards - the damage is done and the remaining pieces are unstable. This is not a watch-and-wait situation; it is a call. If a limb or tree is on the house or a power line, treat it as an emergency and stay clear of any wires.

Which signs mean call now

Not all warning signs are equally urgent. Here is a rough triage:

Don't guess in the gray zone

The tricky part is that several of these signs live in a gray zone - a cavity might be superficial or serious, a lean might be old or moving. That is exactly what an on-site arborist consultation is for: a trained eye can usually tell whether a defect is cosmetic or structural, and give you a straight recommendation rather than a guess. Reading these signs yourself tells you when to ask; the on-site look tells you what to do.

If a tree on your property is showing any of these signs - anywhere across Evanston, Northbrook, Lake Forest, and the North Shore - request a free on-site estimate and a crew lead will assess the risk and tell you honestly whether it needs to come down, needs pruning, or is fine to leave.