Cracked bark on a tree in winter
Cracked, sunken or peeling bark in winter most often comes from two different kinds of damage: sunscald and frost cracks. This page describes what each looks like, why it happens, which trees are at risk and what to do. This is general information, not a diagnosis: from a description alone we cannot say what exactly happened to your tree.
At a glance
- Sunscald
- Discoloured, sunken, cracked or peeling bark — most often on the south or west side.
- Frost crack
- A vertical crack in the bark and wood that opens in the cold and closes as it warms — often year after year.
- When
- Both kinds of damage happen in winter.
- At risk
- Young trees with thin bark, including fruit trees.
- Prevention
- White guards or white latex paint, especially on the southwest side.
- What not to do
- Do not apply wound dressings, sealants or paint — they do not aid healing.
- Healing
- The tree grows a raised callus to try to close the wound.
Sunscald (southwest injury)
On sunny winter days the bark on the south and west sides of the trunk warms up and can reactivate the cambium — the tissue just under the bark. When it cools quickly in the evening and the temperature drops below freezing, these active cells are injured and die.
The bark may become discoloured, sink, crack or peel away over the dead tissue.
Trees under stress — from drought, environmental factors, herbicide injury or pests and diseases — are more prone to it. Trees that go into winter well watered are better protected than drought-stressed ones.
Frost cracks
These are vertical cracks in the bark and wood of the trunk or branches that appear in winter. They come from an imperfection in the wood that tends to open and close every year: low temperatures reopen them and they close again as it warms. They usually trace back to an earlier injury to the tree.
The tree may grow a raised callus to try to close over the wound. The crack can be an entry point for decay fungi and insects.
How to tell them apart
- Sunscald: discoloured, sunken, cracked or peeling bark — most often on the south or west side.
- Frost crack: a vertical crack that opens in the cold and closes as it warms, sometimes with a raised callus along it.
What to do about existing damage
- Carefully remove loose or hanging bark with a clean, sharp tool, without damaging healthy bark.
- Do not apply wound dressings, sealants or tree paint to exposed wood — they do not improve healing and may interfere with it.
- Do not cover the damaged area with tarps, burlap or plastic sheeting.
- Water properly, especially young trees and during dry spells.
How to protect the tree
- Use light-coloured, preferably white guards that are ventilated so they do not girdle the trunk.
- Or paint the trunk with white latex paint, especially on the southwest side — most useful in the first few years after planting.
- Wrap the trunks of young trees with white tree wrap in late fall, before freezing temperatures, and remove it in spring — for at least the first two to three winters after planting.
- Water trees well in the fall before the ground freezes — drought-stressed trees are more susceptible.
What cannot be determined from a description alone
The sources distinguish sunscald from frost cracks by the kind of damage, but they do not say whether your tree will recover or whether something else was involved. If you are unsure, a photo and description give a better basis.
Common questions
Why does tree bark crack in winter?
Most often from sunscald — the sun warms the bark and the temperature then drops quickly below freezing in the evening — or from a frost crack, when low temperatures reopen an imperfection in the wood left by an earlier injury.
Which trees are most at risk?
Young trees with thin bark, including fruit trees, and trees under stress, for example from drought.
Should I cover the wound with paint?
No. Wound dressings, sealants and paint do not aid healing and may interfere with it. Remove loose bark with a clean, sharp tool and leave the area open.
Will the tree survive?
The sources do not say whether a particular tree will recover. The tree tries to close the wound with callus on its own, and proper watering is especially important for young trees with bark damage.
How do I prevent it?
With light-coloured guards or white latex paint on the southwest side, white wrap for young trees in their first winters and good watering in the fall.
Important: This page is general background for a home garden and does not replace an on-site look or a specialist's advice. It names no spray products: for crop protection, always follow the product label and the rules in force.
Related calendars
More seasonal tips
Sources
This page was checked against the public reference below. It is general background, not a diagnosis of a specific plant.
- University of Wisconsin Fruit Program (A. Atucha, 2025) — Understanding and preventing southwest injury (sunscald) in young trees
- Utah State University Extension — Sunscald injury or southwest winter injury on deciduous trees (Utah Forest Facts 021)
- Iowa State University Extension — Shedding, peeling and splitting bark on shade trees
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