Why are my peach tree leaves curling and blistering?

Curled, puckered, blistered leaves that flush pink and then brown in spring are a near-certain sign of peach leaf curl — one of the most widespread fungal diseases affecting peach and nectarine trees. It is caused by the fungus Taphrina deformans and, left unchecked, it can significantly weaken a tree year after year by stripping it of functional leaf cover.

What peach leaf curl looks like

The disease first shows as pale areas on emerging leaves in early spring. Within days those areas swell and blister, turning deep pink to red as the fungal spores develop. Affected leaves thicken and feel leathery or rubbery to the touch. Eventually a white powdery coating appears — the spore layer — and the leaves turn brown and fall prematurely. The tree often pushes a second flush of healthy leaves after the infected ones drop, but this late growth weakens the tree before winter.

How the fungus overwinters

The spores of Taphrina deformans spend winter lodged in the bark, in bud scales, and on the surface of dormant wood. When temperatures rise in late winter and the buds begin to swell, spores germinate and penetrate the young leaf tissue as it unfurls. Cool, wet springs cause the worst outbreaks because the leaves expand slowly, giving spores more time to infect them.

The only effective spray window

Fungicide sprays must be applied before bud swell — typically late January to early February in the UK. Apply a copper-based product (copper hydroxide or Bordeaux mixture) when buds are fully dormant but just beginning to show the first signs of movement. A second application in autumn as leaves fall helps reduce the spore load on the bark. Once leaves are open and symptoms are visible, spraying will not cure the infected foliage that season.

Removing infected leaves by hand

Pick off and bin — never compost — every affected leaf as soon as you spot it. This reduces the spore population that will overwinter on the tree. For a heavily infected tree with hundreds of blistered leaves, removing them promptly shortens the period during which spores ripen and fall back onto the bark.

Physical barriers and fan-trained trees

Fan-trained peaches grown against a wall can be protected by a simple polythene rain shelter erected from November to May. Because the fungus needs wet conditions to infect, keeping rain off the buds and young leaves during the critical period is extremely effective — often eliminating the disease entirely without any chemical input. Free-standing trees are harder to shelter but temporary fleece frames can help in high-risk years.

Building long-term resistance

Feed the tree well in spring with a balanced fertiliser after the infected leaves have dropped. A tree with a healthy root system and a full second flush of leaves will recover well from a single bad year. Repeated annual infection, however, steadily reduces vigour, so consistent winter spraying and prompt leaf removal are worthwhile habits.