Don’t let your tree die from disease and insect infestations when its bark splits. Treating your tree quickly after its bark splits is essential to its health and vigor.

toddsmariettatreeservices.com gathered information on why tree bark splits or cracks and what you can do to prevent it or treat it.

What Causes Tree Bark Splitting

Tree bark can split or crack for many reasons, and you cannot fix it. You can protect your tree while it compartmentalizes the damage and protect others by taking preventative measures.

While it is a more common occurrence on younger trees, all trees are susceptible to bark splitting when exposed to the following:

Sunscald (Southwest Winter Injury) – In the winter months, the south and southwest sides of young trees are prone to sunscald. This condition occurs on warm winter days when the bark exposed to the sun heats up substantially and is then exposed to freezing temperatures. This super-heating, followed by super-cooling, frequently causes the death of the inner-bark.

Such injuries only become visible during the spring growing season and appear as sunken or discolored bark, which splits and may fall off in patches. This damage presents an avenue for pests and diseases to attack the tree successfully.

This condition may also occur on the trunk and branches of mature trees if they were heavily pruned in the fall.

Sunscald Treatment:

When you detect that your tree is suffering from sunscald, treatment involves letting the tree work to heal itself. Damaged areas of the bark or limbs should not be filled with a sealer or painted.

Lightly trimming the wound (tracing the injury with a sharp knife) to help the tree compartmentalize the exposed area and wrapping the damaged area with a light-colored tree wrap can help accelerate the healing process.

Sunscald Prevention:

Protecting trees from sunscald is incredibly easy and inexpensive. All available measures include keeping the trunk and lower limbs either insulated or shaded in winter. The following are some of those measures:

• Plant the tree in an area shaded by structures in the late afternoon
• Use white-colored tree wraps (white reflects sunlight and prevents bark overheating)
• Plant evergreen trees or shrubs to shade the southwest side of your trees

Frost Cracks – The conditions that cause frost cracks are similar to those that cause sunscald. This condition occurs in late winter and early spring as water contained in the phloem, xylem, wood, and inner bark expands and contracts while repeatedly freezing and thawing with fluctuating temperatures.

The resulting injury to the tree appears as a crack in the bark, potentially reaching several feet in length.

Frost Crack Treatment:

Similar to sunscald, no sealant should be used to dress the resulting wound, and a light-colored tree wrap can be used to protect the wound while the tree heals itself.

Frost Crack Prevention:

Frost cracks are often the result of previous damage to the tree or off-season growth. Use the following measures to reduce the risk of frost crack injuries:

• Protect your tree trunks and branches from injury at all times
• Fertilize in late fall or early spring (do not fertilize during summer and early fall months)
• Conduct pruning activities in late fall and winter months

Like fertilizing, pruning entices a tree to grow. Spring and summer pruning may result in growth that will not have time to properly harden for winter months and become highly susceptible to frost cracks.

Environmental Conditions (Drought) – Bark splitting can also be caused by long periods of drought, followed by exceptionally wet periods of growth.

The longer trees suffer scarce water conditions, the thirstier they will get, and the less flexible they will become. When that dry period is followed by excessively wet conditions, trees (especially young trees) will over-satiate their hydraulic systems, often resulting in “bloating.” As the tree bloats, pressure builds against the hardened inner bark and may split the bark if that pressure becomes too high.

Bark Splitting Treatment:

As this condition typically occurs during the growth cycle of a tree, protecting the resulting wounds from insect infestation and disease is essential. Recommended treatment measures are identical to those for sunscald.

Bark Splitting Prevention:

During periods of drought, the following measures will help your trees maintain their elasticity and remain hydrated:

• Apply a three to six-inch layer of organic mulch from the tree’s root flare to the edge of the canopy (this covers and regulates the moisture for the root plate)
• Provide two to three deep waterings per week (deep waterings allow water to soak ten to fifteen-inches into the soil)
• Do not prune your tree after periods of drought. Allow time for them to recover fully
• Fertilize sparingly and only in late fall to prevent untimely growth

Herbicides (Glyphosate Products) – Weed killers may be doing more than killing your weeds. Bark splitting on the south and southwest face of trees from freezing and thawing patterns may be caused by the glyphosate herbicides that you are using to combat pesky weeds.

When these herbicides are applied directly to tree bark (accidentally or purposefully), applied too frequently in the vicinity of trees, or used in overly high doses on the surrounding landscape, the glyphosate in the products deteriorates the inner bark structure while eliminating the winter hardiness of the trees (especially young trees).

How to Prevent Glyphosate Damage:

• Use a herbicide containing no adjuvant (wetting agent)
• Use correct dosages (do not overspray)
• Maintain a thirty to forty-foot no-spray zone between the weeds you spray and your trees
• Do not use herbicides to treat tree suckers (the roots will carry the herbicide to the tree)
• Reduce the use of glyphosate by integrating other methods of weed removal

All herbicides are accompanied by benefits and risks. By following the instructions on the label, you can maximize the benefits while reducing the risks.

Preventing Bark Splitting

In this article, you discovered what causes tree bark to split, what you can do to treat it, and ways to prevent the condition.

By taking preventative measures to protect your trees through winter months and from harmful chemicals, your trees can mature with higher resistance to insect infestation and disease.

When you ignore signs of bark splitting or cracking, you are leaving your tree highly vulnerable to a rapid decline in its health and potential death.

Sources:
cals.arizona.edu/yavapai/anr/hort/byg/archive/sunscald2017.html
extension.usu.edu/archive/bark-splitting-caused-by-common-herbicide
plantclinic.cornell.edu/factsheets/barksplitting.pdf
extension.tennessee.edu/publications/Documents/SP630.pdf