How Do You Prune Cherry Trees Without Causing Disease?

Cherry trees are beautiful but demanding when it comes to pruning. Like all stone fruits, they are highly susceptible to bacterial canker and silver leaf disease, both of which enter through pruning cuts made at the wrong time of year. The rule is simple but non-negotiable: prune cherries in summer, not in autumn or winter. Understanding why this matters — and how to prune differently depending on whether you have sweet or acid cherries — makes the whole job straightforward.

The Summer Pruning Rule

Bacterial canker (Pseudomonas syringae) and silver leaf (Chondrostereum purpureum) both overwinter in the environment and release spores or bacteria during cold damp weather. By pruning sweet cherries in July, and acid cherries immediately after harvest in late summer, you time cuts for the driest period of the year with the lowest disease pressure. The wound heals faster in warm weather too, because the tree is actively growing and producing protective callus tissue.

Sweet Cherries: Minimal Pruning Needed

Sweet cherries are vigorous — they will reach eight metres or more on a standard rootstock. For freestanding trees, the main job is keeping the tree to a manageable size and removing dead, diseased, and crossing wood. Sweet cherries fruit on both one-year-old shoots and older spurs. Avoid hard pruning: removing large amounts of wood stimulates very vigorous regrowth and creates large wounds that are difficult to seal. Light and consistent annual pruning is always better than infrequent hard cutting.

Acid Cherries: Prune for New Wood

Acid cherries, including the popular Morello, fruit almost exclusively on the previous year's growth. This means you need to prune to keep a supply of young shoots coming through every season — very different from the spur management approach used with sweet cherries. After harvest, cut back some of the fruited shoots to a younger shoot lower down the branch. This keeps the fruiting wood close to the framework and prevents the tree from producing all its cherries at the tips of long bare branches.

Recognising and Dealing with Bacterial Canker

Bacterial canker shows as sunken, dark, weeping patches on the bark, with gum oozing from the wound. In spring, affected branches may fail to leaf out at all. When you see canker, cut back the affected branch to healthy wood — at least 15 cm below the visible lesion — and sterilise your tools between cuts. Dispose of infected material away from the garden. Copper-based sprays applied in autumn can help reduce the spread of the bacteria but are not a substitute for good pruning hygiene and correct timing.