Are cracks in a tree trunk dangerous?
A vertical split in the trunk, a crack running down out of a fork, or a seam that has opened along the stem — sometimes with sound or movement in the wind.
Treat the ground beneath the tree as off limits and get eyes on it now. These are the conditions that end in something falling.
Some are, and the difference is not subtle once you know what to look at. A crack that runs through a fork holding two large stems, one you can slide a coin into, or one that opens and closes as the tree moves in wind, is a structural failure already in progress. A shallow, callused frost crack on the southwest side that has been there for years is a different matter. When you cannot tell which you have, assume the first one.
What this looks like
Look at where the crack starts and where it goes. A frost crack is a straight vertical seam, usually on the south or southwest face, often with raised callus ribs on both sides from years of reopening. A structural crack starts at a fork and runs down into the trunk, and the two stems above it move independently. The most serious presentation of all is a pair of cracks on opposite sides of the trunk at the same height, which describes a shear plane running through the stem.
- A crack passing through the union where two large stems or limbs meet
- A gap wide enough to insert a coin, or one you can see into
- Matching cracks on opposite sides of the trunk at the same height
- Rust-colored staining, wet streaks, or fungal conks along the crack
What causes it in Kansas
Roughly in order of how often each turns out to be the answer here. The line under each one is what separates it from the others — open a cause for the detail.
1Failing weak unions
How to tell: The crack begins at the crotch and runs down; the stems above visibly shift relative to each other in wind.Where two stems of similar size grow from the same point, the attachment is often bark-to-bark rather than wood-to-wood and has a fraction of the strength it appears to. Under wind or ice the union begins to split from the top of the fork downward. Bradford pear built its reputation in Kansas on precisely this failure.
2Storm torque
How to tell: Fresh pale wood in the crack, appearing right after a significant weather event.Wind twists a crown as well as pushing it, and the resulting cracks frequently do not finish failing during the storm. A limb or stem cracked in June can hold until an ordinary August gust.
3Frost cracks and radial shakes
How to tell: A vertical seam on the sunny side with raised ribs of callus down both edges, present for several years without changing.Rapid winter temperature swings make the outer wood contract faster than the interior, and the trunk splits along a radius. It reopens in cold weather and callouses over each summer.
4Internal decay reaching the surface
How to tell: Soft or hollow-sounding wood near the crack, conks on the trunk, or an old wound or pruning stub in line with it.A column of decay in the trunk reduces the wood's ability to resist bending, and a crack opens along the weakest line. This version tends to appear on a tree with other symptoms already present.
5Lightning
How to tell: A long, sometimes spiraling wound with blown-out bark, dating to a specific storm.A strike can split a trunk deeply, occasionally the full length, and the damage is immediate and severe.
What to do, and what to avoid
Safe to check yourself
All from the ground — no ladder, no saw.
- Trace where the crack begins and ends, from the ground and from a distance — a crack through a fork is the one that matters most
- Keep everyone out of the fall zone until it is assessed, and note what sits under it
- Look for a second crack on the opposite side at the same height
- In wind, watch whether the two sides of the union move independently — from a safe distance
What not to do
The responses that make this one worse or permanent.
- Do not install bolts, straps, or cables yourself; hardware placed wrong makes failure more likely and hides the problem while doing it
- Do not fill the crack with foam, concrete, or caulk
- Do not park, store equipment, or set up seating under a cracked stem while you decide
- Do not assume a callused old crack is fine on a tree that has grown much heavier since it formed
When to contact an arborist
Dealing with this in the Wichita area right now?
Hazardous-tree work is where equipment, training, and insurance stop being optional. Kohnen's Tree Service handles emergency assessments, storm response, and hazardous removals across Wichita and the surrounding communities.
When a situation calls for professional help in the Wichita area, we refer readers to Kohnen's Tree Service, a working Kansas tree-care company whose field experience informs this site. That relationship is disclosed here and on our About page.
Whatever this narrows it down to, the assessment that decides what happens next has to happen at the tree. Why that is
Common questions
There has been a crack in my maple for ten years. Should I worry now?
There has been a crack in my maple for ten years. Should I worry now?
Long-standing frost cracks with callus ribs on both sides are usually stable, but the tree above them has kept growing and now weighs considerably more. Any change — widening, staining, fungal growth, or new movement — resets the assessment.
Will cabling fix a split Bradford pear?
Will cabling fix a split Bradford pear?
Sometimes it buys years. Cabling reduces the load on a weak union but does not repair it, it requires periodic inspection, and it is a poor investment on a species that will simply produce the next failure elsewhere. Many Kansas Bradford pears reach the point where replacement is the better decision.
Can a tree heal a crack?
Can a tree heal a crack?
Trees do not heal; they compartmentalize. New wood grows over and around the injury, walling it off, and the crack stays inside the trunk permanently. A tree can absolutely stabilize a crack this way — it just never gets its original strength back at that spot.
Kansas Tree Guide is an independent educational resource. Nothing on this site replaces an on-site assessment by a qualified arborist or tree-care professional. Last reviewed August 2026.
Often seen alongside this
A second symptom narrows the cause faster than more detail about the first.
Not what you are seeing? Work the symptom guide again.