Why Is My Pear Tree Bark Splitting?

Bark splitting on a pear tree can range from a completely normal feature of vigorous growth to a serious sign of disease or frost injury. The location of the split, its appearance, and whether it is accompanied by discolouration, oozing or dead wood underneath are the key things to look at before deciding whether action is needed.

Natural growth splitting

Vigorous young pear trees commonly develop shallow longitudinal cracks in smooth bark on the trunk and main branches. This is the outer bark splitting as the underlying cambium layer expands rapidly during a flush of growth. These cracks typically run cleanly along the grain of the bark, show no sunken or dead tissue, and the tree continues to grow strongly with no other symptoms. They are not a problem and require no treatment. The bark eventually thickens and develops its characteristic rough, plated texture that is less prone to splitting.

Frost crack

Sharp overnight frosts following warm days in late winter or early spring can cause the outer bark to contract faster than the inner wood, producing a sudden longitudinal split, sometimes accompanied by a cracking sound. Frost cracks are most common on the south-facing side of the trunk, which heats up significantly during sunny days before freezing at night. The crack often closes again as temperatures warm in spring. Protecting young trees with a tree guard or wrapping the trunk with hessian through the coldest months significantly reduces the risk.

Canker — the serious cause

Pear canker (Neonectria galligena) causes a very different type of bark damage. Infected areas develop a sunken, discoloured, flaking lesion — usually elliptical — with concentric rings of dead bark. The wood underneath is brown and dead. Canker enters through wounds: pruning cuts, frost damage, insect feeding sites and leaf scars. Cut out affected wood well into healthy tissue, disinfecting tools between cuts. Burn or bag the prunings — do not compost them. In wet years, canker can be very active; improve air circulation through the canopy and avoid creating unnecessary wounds.

Fireblight bark lesions

Fireblight (Erwinia amylovora) can cause bark splitting on branches as the bacterial infection spreads into the wood. Affected bark often shows a water-soaked appearance initially, then becomes sunken and may exude a bacterial ooze in damp weather. The wood underneath reveals a characteristic reddish-brown staining when cut. Fireblight is a notifiable disease in some countries. Prune well into healthy wood, sterilise tools between every cut with a 10% bleach solution or methylated spirits, and do not leave prunings on site.