Tree Bark Peeling or Falling Off: Disease vs Natural Causes
Bark peeling off a tree can be alarming, but it is not always a sign of trouble. Some species shed bark naturally as they grow, while in others it signals disease, environmental damage, or structural decline. This guide helps you distinguish normal bark shedding from problems that need attention.
Quick Answer
Tree bark peeling is normal for sycamore, birch, crape myrtle, paperbark maple, and shagbark hickory. For other species, peeling bark may indicate disease (cytospora canker, hypoxylon canker), frost crack damage, sunscald, or that the underlying tissue has died. The key diagnostic test is examining the wood beneath the peeling bark: green and moist tissue means the tree is healthy; brown and dry tissue means that section has died. If bark loss extends around more than a third of the trunk, consult an arborist.
Species That Naturally Shed Bark
Several common landscape and forest trees shed bark as a normal part of their growth. As the trunk expands, the rigid outer bark cannot stretch to accommodate the new girth and cracks, peels, or flakes off to reveal fresh inner bark. This is a perfectly healthy process and one of the identifying features of these species.
Sycamore (Platanus)
Sheds large patches of brown outer bark to reveal smooth, cream-white inner bark, creating a mottled, camouflage-like pattern. This is the most dramatic bark shedding of any common landscape tree and is completely normal. London plane tree behaves similarly.
Birch (Betula)
Paper birch, river birch, and yellow birch all shed bark in papery strips or curls. River birch peels in salmon-pink to reddish-brown strips. Paper birch sheds white, papery bark. This natural exfoliation is a prized ornamental feature. Browse river birch and paper birch profiles.
Crape Myrtle (Lagerstroemia)
Sheds thin strips of bark to reveal smooth, colorful inner bark in shades of tan, cinnamon, gray, and cream. This multicolored exfoliating bark is one of the species' main ornamental attractions, especially in winter.
Shagbark Hickory (Carya ovata)
Named for its distinctive bark that peels in long, vertical strips that curve away from the trunk at the top and bottom, giving the tree a shaggy appearance. This is completely normal and makes the species easy to identify even in winter.
Scotch Pine & Red Cedar
Scotch pine sheds orange-brown bark in thin flakes from its upper trunk and branches. Eastern red cedar sheds fibrous strips of gray-brown bark. Both processes are normal and do not indicate disease.
Paperbark Maple (Acer griseum)
One of the most ornamental bark-shedding species, paperbark maple exfoliates in thin, cinnamon-brown sheets that curl tightly, creating a stunning textural display year-round.
Disease Causes of Bark Loss
Cytospora Canker
Cytospora canker, caused by fungi in the genus Cytospora (also known as Valsa), is one of the most common bark diseases in North America. It creates sunken, discolored cankers on the trunk and branches, often with amber-colored resin oozing from the affected bark. As the canker expands, the bark dies and falls away. Cytospora commonly attacks spruce (particularly Colorado blue spruce), poplar, willow, and stone fruit trees. Stressed trees are most susceptible. Management involves removing infected branches, improving tree vigor, and avoiding wounds during wet weather.
Hypoxylon Canker
Hypoxylon canker is caused by fungi in the genus Biscogniauxia (formerly Hypoxylon). It manifests as a dark, hard, crusty coating on dead bark, often on the south or west side of the trunk. The fungus is a secondary invader that colonizes trees already severely stressed by drought, root damage, or compaction. Bark affected by hypoxylon eventually sloughs off in large sheets. Hypoxylon canker commonly attacks oaks, especially post oak and live oak in the southern United States, and is almost always associated with severe drought stress. There is no treatment; management focuses on maintaining tree health through watering during drought.
Sunscald (Southwest Injury)
Sunscald occurs when winter sunlight warms the bark on the south or southwest side of the trunk during the day, activating the cambium, followed by rapid freezing after sunset that kills the activated cells. The result is a vertical strip of dead bark on the sun-facing side that eventually cracks and peels. Young trees with thin bark and trees recently exposed to direct sun (after neighboring trees are removed) are most vulnerable. Prevention involves wrapping young tree trunks with white tree wrap or plastic guards from November through March, or painting the trunk with white latex paint to reflect sunlight.
Frost Crack Damage
Frost cracks are vertical splits in the trunk bark caused by rapid temperature changes during winter. When the sun warms one side of the trunk on a cold day, the wood expands; when temperatures drop rapidly after sunset, the outer wood contracts faster than the inner wood, creating tension that splits the bark and sometimes the wood itself. The crack may produce a loud pop or bang when it forms. Frost cracks often run vertically for several feet and may penetrate deep into the wood.
Once a frost crack forms, it typically reopens each winter even though the tree attempts to callus over the wound during the growing season. This cycle of cracking and healing creates a raised ridge of callus tissue along the crack line called a frost rib. While frost cracks are unsightly, they do not usually kill trees. However, they create an entry point for decay fungi that can slowly compromise the trunk over many years.
Species most susceptible to frost cracks include London plane tree, Norway maple, crabapple, horsechestnut, walnut, and young thin-barked trees of any species. Prevention through trunk wrapping or white paint on young trees is more effective than any treatment after cracking occurs.
When to Be Concerned vs. When It's Normal
Normal (No Action Needed)
- Bark peeling on sycamore, birch, crape myrtle, or other known shedding species
- Thin strips or flakes peeling from a healthy tree with a full canopy
- Exposed inner bark is smooth, colorful, and shows no signs of decay
- Minor bark loss at the base from lawn mower damage (monitor but not urgent)
Monitor Closely
- Vertical crack on the south/southwest side (frost crack) — watch for decay entry
- Small cankers on individual branches — prune affected branches
- Bark loss covering less than 25% of the trunk circumference
- Minor sunscald on young trees — apply trunk wrap next winter
Seek Professional Help
- Bark falling off in large sheets to reveal dry, brown, or decayed wood
- Bark loss around more than a third of the trunk circumference
- Oozing, bleeding, or foul-smelling areas on the trunk
- Dark, crusty coating (hypoxylon) on dead bark
- Bark loss combined with canopy decline, dead branches, or fungal growth
- Any bark damage on a tree overhanging structures or high-traffic areas
Quick Identification Guide
When examining peeling bark, ask yourself these diagnostic questions:
- Is this a species known for bark shedding? If yes, it is likely normal. Check the species list above.
- What does the wood look like under the peeling bark? Green, moist, and smooth = healthy. Brown, dry, crumbly = dead tissue.
- Where on the trunk is bark falling off? South/southwest side = sunscald or frost crack. Random pattern = possible disease.
- Is there oozing, staining, or a foul smell? These suggest active disease (bacterial wetwood, Phytophthora, or canker).
- How much of the trunk is affected? Less than 25% = usually manageable. More than 50% = serious concern.
- Is the rest of the tree healthy? Full canopy with good leaf color suggests the bark issue is localized. Thinning canopy and dead branches suggest systemic decline.
Related Guides
Frequently Asked Questions
Is it normal for tree bark to peel off?
For some species, yes. Sycamore, birch, crape myrtle, paperbark maple, shagbark hickory, and certain pines naturally shed bark as part of their growth process. The exposed inner bark is typically smooth and healthy-looking. However, bark peeling on species that do not normally shed, or peeling that reveals dry, brown, or decayed wood, indicates a problem that should be investigated.
What disease causes bark to fall off trees?
Several diseases cause bark loss. Cytospora canker causes sunken, oozing cankers that kill bark on spruce, poplar, and willow. Hypoxylon canker produces a dark, crusty coating on dead bark, primarily on oaks stressed by drought. Phytophthora bleeding canker causes dark, oozing patches on beech, oak, and horse chestnut. Bacterial wetwood causes foul-smelling ooze that kills surrounding bark. In all cases, the bark dies and eventually falls off to expose the dead wood beneath.
What causes frost cracks in tree bark?
Frost cracks occur when winter sunlight warms the bark on the south or southwest side of the trunk during the day, causing the tissue to expand, then rapid cooling after sunset causes the tissue to contract suddenly, splitting the bark vertically. Young trees with thin bark and dark-colored bark species are most susceptible. Once a frost crack forms, it typically reopens each winter. Prevention includes wrapping young tree trunks with protective wrap in fall.
Should I put anything on a tree where bark has fallen off?
In most cases, no. Research has shown that wound dressings and tree paint do not help trees heal and may actually slow the natural compartmentalization process. The exception is fresh oak wounds during oak wilt season (April through July), which should be sealed immediately with pruning paint to prevent beetle access. For all other species and seasons, simply leave the wound open and allow the tree to form callus tissue naturally.
Can a tree survive without bark?
A tree can survive losing bark on a portion of its circumference, as long as enough cambium (the thin layer of living tissue beneath the bark) remains intact to transport water and nutrients around the damaged area. Trees that lose bark around more than 50 percent of their trunk circumference are unlikely to survive because the remaining cambium cannot support the full canopy. Complete girdling, where bark is removed around the entire circumference, is fatal.
Tree Care Costs
Trunk wrapping for sunscald prevention costs $10 to $30 per tree (DIY). Canker treatment and pruning runs $200 to $500. Arborist assessment of bark damage costs $75 to $200. These investments protect against costly removals later. Find professionals in our arborist directory.