- By the dedicated team of editors and writers at Newsletter Station.
Trees are valuable additions to any landscape. They provide shade, enhance your property's appearance, support wildlife, and contribute to a healthier environment. But even healthy, established trees can suffer damage from severe weather, disease, decay, or physical injury.
A crack in a tree trunk or major branch can be concerning because it may indicate structural weakness. Some cracks are relatively minor, while others can increase the risk of branch or tree failure, particularly during high winds, heavy snow, or other severe weather.
If you discover a cracked tree, it's important to understand what may have caused the damage, evaluate the surrounding conditions, and determine whether professional tree care is needed.
Understanding What Causes Tree Cracks
Tree cracks can develop for many reasons. Identifying the likely cause can help determine how serious the problem may be.
Storm Damage
Severe weather is one of the most common causes of tree damage. Strong winds, lightning, heavy snow, and ice can place tremendous stress on trunks and branches.
A sudden storm can cause a tree to split, while repeated exposure to wind and weather may gradually worsen an existing weakness. After a major storm, inspect trees for new cracks, broken branches, hanging limbs, or changes in the tree's structure.
Mechanical Injury
Lawn equipment, vehicles, construction activities, and other human activities can damage tree trunks and branches.
A damaged section of bark or wood can become an entry point for insects and disease. Even if the injury doesn't immediately result in a visible crack, it can weaken the tree over time.
When working around trees, keep lawnmowers, string trimmers, vehicles, and construction equipment away from trunks and exposed roots whenever possible.
Weak Branch Unions and Included Bark
Some cracks occur where two major stems or branches meet. Trees with co-dominant stems can develop weak unions, particularly when the stems form a narrow, V-shaped junction.
Included bark can become trapped between the stems, preventing a strong connection from developing. These unions may be more vulnerable to splitting as the tree grows or during severe weather.
Because structural problems at major branch unions can be difficult to evaluate from the ground, an arborist should assess significant cracks in these areas.
Disease and Decay
Internal decay can weaken wood and reduce a tree's ability to withstand stress. Fungal organisms, cavities, and other forms of deterioration may contribute to structural problems.
Decay isn't always visible from the outside. A tree may appear relatively healthy while having significant internal deterioration.
Signs such as mushrooms growing on or near the tree, cavities, dead branches, loose or damaged bark, and areas of soft or decaying wood may warrant professional evaluation.
Sunscald and Temperature Stress
Rapid temperature changes can sometimes contribute to cracks in tree bark. Sunscald, for example, can occur when exposed bark is heated during the day and then freezes at night.
This type of damage is particularly common on thin-barked trees or on portions of trunks that receive intense afternoon sunlight. Bark cracks don't always indicate that the entire tree is structurally compromised, but they should be monitored for additional damage or signs of decay.
How to Assess a Cracked Tree
Not every crack means that a tree needs to be removed. However, certain characteristics can indicate a greater risk.
Look at the Location
The location of a crack is important. A crack in a major trunk or at a significant branch union may be more concerning than a superficial crack in the outer bark.
Pay particular attention to cracks near the base of the trunk, major branch attachments, or areas supporting heavy limbs.
Examine the Crack
Look at the length, direction, and apparent depth of the crack. A crack that extends deeply into the wood or continues through a major structural section deserves professional attention.
Avoid attempting to pry the crack open or probe deeply into it. Doing so can cause additional damage and won't provide a reliable assessment of the tree's structural condition.
Look for Movement or Separation
If portions of the trunk or a major branch appear to be separating, the situation may be more urgent. Cracks that open or move noticeably when the tree is subjected to wind can indicate structural instability.
Keep people, pets, and vehicles away from the area until the tree can be evaluated if you believe there is an immediate danger of failure.
Check the Overall Health of the Tree
Consider the tree's overall condition. Look for dead branches, thinning foliage, damaged bark, mushrooms, cavities, leaning, or other signs of decline.
A tree's health is one factor in evaluating its ability to respond to injury, but even a healthy tree can have a serious structural defect.
What to Do About a Cracked Tree
Once you've identified a crack, the appropriate response depends on its location, severity, and the tree's condition.
Contact a Certified Arborist
If the crack is large, appears deep, affects the trunk or a major branch, or is located near a structure or area where people gather, have the tree evaluated by a qualified arborist.
An arborist can assess the tree's structure, health, surrounding conditions, and potential risk and recommend appropriate steps.
Professional evaluation is especially important when the tree is large or located near a home, driveway, power lines, or other valuable property.
Remove Damaged Branches When Appropriate
If a crack has damaged a branch and the branch needs to be removed, proper pruning can help reduce the immediate hazard.
However, avoid attempting to cut large, heavy, or elevated branches yourself. Tree removal and large-branch pruning can be dangerous, particularly when damaged wood is under tension.
A professional tree-care specialist has the equipment and training needed to handle these situations safely.
Consider Cabling or Bracing When Recommended
In some situations, an arborist may recommend a cabling or bracing system to provide additional support for a tree with structural weaknesses.
These systems aren't appropriate for every cracked tree and should not be installed as a do-it-yourself solution. Proper assessment and installation are necessary to determine whether supplemental support is appropriate.
Don't Try to Seal or Fill the Crack
Older tree-care advice sometimes recommended filling cavities or cracks with cement, foam, or other materials. Modern tree-care practices generally discourage these approaches because they can interfere with natural processes and make future assessment more difficult.
Trees have their own natural mechanisms for compartmentalizing injuries. The goal should be to address hazards and improve the tree's overall condition,n rather than attempting to "repair" a crack in a building.
Monitor the Tree
If an arborist determines that the crack does not currently require corrective action, continue monitoring the tree.
Take photographs of the affected area so you can compare its appearance over time. Watch for changes such as increasing separation, new cracks, dead branches, fungal growth, leaning, or changes in the surrounding soil.
If the condition changes, have the tree reevaluated.
Consider Tree Removal When Necessary
Sometimes a cracked tree cannot be safely preserved. Extensive structural damage, severe decay, significant leaning, or a high likelihood of failure may make removal the safest option.
Tree removal should be considered carefully and, when possible, based on an evaluation by a qualified tree-care professional. Removing a healthy tree unnecessarily can be costly and eliminates many of the environmental benefits trees provide.
How to Help Prevent Tree Damage
While you can't prevent every crack or storm-related injury, good tree care can reduce some risks.
Schedule Regular Inspections
Inspect trees periodically and pay particular attention after major storms. Early detection of weak branches, structural problems, and signs of disease can make management easier.
For large or mature trees near homes and other structures, professional inspections can provide an additional level of protection.
Prune Properly
Proper pruning can help maintain a strong structure and reduce the weight of damaged or poorly positioned branches. Avoid excessive pruning or removing large portions of a tree without professional guidance.
Protect the Trunk and Roots
Be careful when operating lawn equipment around trees. Avoid striking the trunk with mowers or string trimmers, and don't unnecessarily disturb the soil around the root zone.
Protecting roots is just as important as protecting the visible portions of the tree because root damage can affect stability and overall health.
Maintain Proper Soil Moisture
During periods of drought, appropriate watering can help support tree health. Mulch can also help retain soil moisture and moderate soil temperatures.
Keep mulch away from direct contact with the trunk, however. A layer of mulch piled against the trunk can create conditions that contribute to bark problems and decay.
When a Cracked Tree Requires Immediate Attention
Some situations should not wait for a routine inspection. Contact a professional promptly if you notice:
A large crack extending through the trunk
A major branch that is split or partially detached
Significant separation at a major branch union
A tree that has suddenly begun leaning
Large hanging or broken branches
A cracked tree located directly over a home, driveway, walkway, or frequently used area
Signs that the tree or a major limb is moving or failing
If a damaged tree is near electrical lines, stay away and contact the appropriate utility provider rather than attempting to address the problem yourself.
Protect Your Trees and Your Property
A cracked tree can be alarming, but not every crack means that a tree must be removed. The right response depends on the crack's location and characteristics, the tree's overall health, and the potential consequences if a branch or the tree were to fail.
Regular inspections, proper pruning, good tree maintenance, and prompt attention after severe weather can help identify problems before they become more serious.
When you're unsure about the condition of a cracked tree, professional evaluation is the safest approach. A qualified arborist can help determine whether the tree can be monitored, supported, pruned, or preserved—or whether removal is necessary to protect people and property.
With the right care and attention, many trees can continue to provide shade, beauty, wildlife habitat, and environmental benefits for years to come.
