Why Is My Cherry Tree Bark Splitting?

Bark splitting on a cherry tree can range from a cosmetic blemish to a serious structural problem depending on where it occurs, how deep it goes, and whether it is accompanied by oozing, dead tissue or unusual colouring. Cherry trees are more prone to bark problems than many other fruit trees because their bark is relatively thin and the wood inside expands and contracts strongly with temperature changes.

Frost crack — vertical splits after cold nights

Frost cracks are long, vertical splits on the main trunk or large branches, typically appearing in late winter or after a sudden cold snap following a mild spell. They form because the outer bark cools and contracts faster than the warm sapwood beneath, creating enough tension to crack the bark. They are most common on south-facing sides of trunks where daytime sun warming is followed by rapid nighttime cooling. Frost cracks rarely kill trees — many callus over naturally in spring — but they provide entry points for disease. Clean any ragged edges with a sharp knife and allow to dry in open air. Do not use wound sealants on fresh splits.

Bacterial canker — sunken, oozing splits

Bacterial canker (Pseudomonas syringae) causes sunken, discoloured areas of bark that crack and exude amber-coloured gum. Unlike a clean frost crack, canker-affected bark looks dead and discoloured, and you may see die-back of branches beyond the affected area. Pruning out infected branches to clean, healthy wood at least 10 cm below the visible margin is the only reliable control. Prune in dry summer weather when bacterial spread is lowest, and sterilise tools between cuts. Apply a copper fungicide spray to wounds and remaining bark in autumn.

Rapid growth splitting

Young cherry trees in their first few years of active growth sometimes split the bark on small branches simply because the wood is expanding faster than the bark can stretch. These splits appear in spring on current-season growth, are shallow, and callus over quickly without intervention. They are most common after a fertiliser application or very wet spring on a vigorously growing tree. They rarely cause lasting harm.

Physical damage

Lawn mower impact, strimmer damage and tight tree ties all cause bark splitting at ground level or where ties are located. Check the base of the trunk and all ties regularly. If a tie is cutting into bark, loosen or remove it immediately. Strimmer guards fitted around the base of the trunk prevent the most common type of mechanical bark damage.

Callusing over — when to wait

A clean split with healthy-looking greenish or cream tissue beneath is likely to callus over without intervention if the tree is otherwise vigorous. Keep the area dry, avoid applying any product that traps moisture, and monitor over the following months. If the exposed wood darkens, shrinks and begins to look dead, bacterial canker or a secondary fungal infection has taken hold and action is needed.