Why Is My Oak Tree Bark Splitting?

Date January 21, 2022


Author TreeNewal Staff

If you’ve been noticing that the bark on your oak tree is splitting, don’t worry – you’re far from alone! It can be a common problem for them but also may be completely normal! So, if you’re wondering what’s causing the split and how to fix it, TreeNewal Professional Tree Care is here to help you demystify and even remedy your splitting bark.

Causes of Splitting Bark

Before any panicking, there are many possible reasons your oak tree’s bark may be splitting.

  • In springtime, peeling bark near the base may be simply part of the natural exfoliation process. Think of it like a lizard shedding its old skin. As your trees are ‘awakening’ from dormancy, the outer layers that have since died are now splitting to make room for regrowth and expansion of trunk diameter. The severity of this process will vary between tree species. Nothing likely to worry about here, but keep an eye out for a while just to be sure.
  • Tree bark contains large amounts of water. So, with sharp, sudden changes in temperature being so common in North Texas winters, trees can struggle with sharp, sudden swelling and shrinking caused by the temperature fluctuation. If the expansion is too quick, it’s easy for the bark to split. This often is referred to as sunscald. Though sunscald typically causes other effects as well, bark splitting is generally the most noticeable.
  • If you notice any oozing of sap coming from the bark splits, then there is cause for immediate concern. It’s very possible bacteria may be to blame. Bacterial wetwood is an infection often contracted through open bark wounds. Once the infection sets into the tree’s core, it causes large amounts of sap to build up high-pressure gas. The only way for the gas and sap to release is for the infected bark to split open. Vertical streaks of residue on the bark are a typical symptom that bacterial wetwood is present. The affliction is also known as ‘slime flux’ due to the oozing sap.

How to Treat and Prevent Splitting Bark of Oak Trees

If your tree bark is likely splitting as a natural exfoliation process, no need for any treatment! Just let nature do what it does best, and it should take care of itself. At worst, there may be a slight ridge where regrown bark meets the split sections and not much else. If you catch this process early on, consider adding some extra fertilizer around the roots to give the tree’s nutrients an encouraging little boost!

If wintery sunscald is what you’re dealing with, don’t be tempted to fill in the splits with a sealer or paint over them. Gently trimming around the wound to keep the damage contained is the first step. Then wrap the affected bark with a white or otherwise reflective blanket or even Kraft paper to help the tree stabilize its inner temperature while it heals. To prevent sunscald, wrap the trunks with said blankets and paper as soon as you see the prediction of sharp temperature changes in the forecast.

If you suspect bacterial wetwood may be the cause of your tree’s splitting bark, unfortunately, there is no cure once the infection has set in, only treatment for managing it is best handled by calling in certified arborists. However, prevention is possible! When pruning your trees, follow all best practices, and if a wound occurs, take quick action to seal them so carrier insects can be avoided.

If your oak tree is exhibiting signs of bark splitting, it’s important to try and determine the cause as soon as possible. While some causes, like natural shedding in spring and sunscald in winter, are beyond your control, there are things you can do to prevent or treat a bacterial infection. If you have any questions about what to do next or need help identifying the cause of your tree’s bark splitting, don’t hesitate to call a professional arborist for assistance.

If you need help determining what’s afflicting the bark of your oak trees or how to treat it, get in touch with the ISA-certified arborists at TreeNewal and enjoy tailored tree care advice.


To learn more about Why Is My Oak Tree Bark Splitting?, call our Argyle and Southlake-based teams

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