Most healthy trees outlive the humans who plant them. But a tree in decline can sit looking 'mostly fine' for two or three years before it suddenly drops a 4,000-pound limb on a parked car. Here are the seven warning signs we tell every Omaha homeowner to watch for.
1. A trunk crack you can see daylight through
Vertical cracks down the main trunk are a structural problem. A crack you can fit a pencil into is concerning. A crack you can see through is an emergency. The tree is mechanically failing and it will eventually split — usually in a storm, usually at the worst time.
2. Mushrooms or fungal conks at the base
Mushrooms growing out of the root flare or low on the trunk mean the wood inside is rotting. The tree might look perfectly healthy on top — full canopy, normal leaves — but the structural wood at the base is being broken down. Trees with significant butt rot often fail catastrophically because the failure point is below grade where nobody can see it.
If you spot a hard, shelf-like growth on the trunk (called a 'conk'), get an arborist out within the month.
3. Major dead wood in the canopy
A few dead twigs are normal. Multiple large dead limbs — branches over 2 inches in diameter, no leaves in the growing season, gray bark — are not. They tell you the tree is failing to push water and nutrients to those limbs.
If more than a quarter of the canopy is dead, the tree is usually past the point of saving.
4. The tree is leaning more than it used to
Some trees lean naturally — they grew that way reaching for sunlight. The dangerous lean is the new lean, especially after a storm. If you see fresh-disturbed soil on one side of the root flare or roots lifting out of the ground on the opposite side, the tree is failing and could come down soon.
5. The bark is peeling in large sheets
Bark naturally exfoliates in some species (sycamore, river birch). What you're watching for is large sheets of bark falling off and exposing smooth dead wood underneath, on species that don't normally peel. That's a sign the cambium layer has died beneath, which means the tree is no longer growing in that zone.
6. Hollow trunk
You can usually hear it — a dead, drum-like sound when you tap the trunk with a hammer. Some hollow is okay; trees can survive with a remarkable amount of interior void if there's enough solid wood around the perimeter. But more than about a third hollow, and the tree's structural reserve is gone.
We can do a resistograph test (drills a small bit into the trunk and measures resistance) to confirm. About $150 and it tells you everything you need to know.
7. Emerald ash borer signs
If you have a green ash, white ash, or any Fraxinus species in Omaha and you haven't treated it: it's almost certainly infested or about to be. EAB has decimated our metro's ash population. Signs:
- D-shaped exit holes in the bark
- Bark splits with serpentine galleries underneath
- Sparse canopy, especially starting at the top
- Woodpecker activity (they go after the larvae)
Once you see EAB symptoms, untreated trees are typically dead within 2-4 years. We recommend removal-and-replant rather than fighting it.
When to call
If you see any one of these signs on a mature tree, get an arborist out for a free assessment. We'd rather come out and tell you the tree is fine than show up with a chainsaw after it's already on your house. Most Omaha removals could have been planned removals at half the price and zero property damage if someone had spotted the signs six months earlier.