Why are my peach tree leaves turning silvery?

A metallic silver or pale lead-coloured sheen on the upper surface of peach or nectarine leaves — particularly on one or two branches rather than the whole tree — is the characteristic early symptom of silver leaf disease. It is caused by the pathogen Chondrostereum purpureum and is one of the most serious fungal diseases that can affect stone fruit trees.

How silver leaf works

The fungus enters through wounds — pruning cuts, broken branches, frost cracks — and colonises the wood. As it grows, it produces toxins that travel through the vascular system and cause the cells beneath the leaf cuticle to separate, creating a reflective air pocket between the epidermis and the cell layer below. This gives the characteristic silvery sheen. The fungus itself never reaches the leaf — the silvering is an indirect symptom of internal wood infection.

Confirming the diagnosis

The definitive diagnostic test is to cut an affected branch about 5–10 cm behind the last visibly silvered leaf. If the internal wood shows a brown or purple stain in the cross-section, silver leaf is confirmed. Unaffected wood is white or cream. If there is no stain and the silvering is uniform across the whole tree, consider "false silver leaf" — a physiological condition caused by drought or root damage that produces a similar appearance without fungal staining.

Cutting out infected wood

Act promptly. Cut back each affected branch to at least 15 cm beyond the last visible brown stain in the wood. Sterilise tools with 70% alcohol or a 10% bleach solution between every cut. Bag or burn all removed material immediately — do not leave it near the tree. If staining is found near the main trunk, the prognosis is poor, but cutting back aggressively to clean wood and feeding the tree well gives it the best chance of mounting a natural defence.

Preventing infection through pruning

Prune peaches only in dry summer weather — June to August — when spores of Chondrostereum purpureum are least active in the air and wound closure is fastest. Seal all pruning cuts larger than 1 cm with pruning compound. Avoid pruning in autumn and winter when spore release is highest and wounds heal slowly, leaving the vascular tissue exposed for many weeks.

If the tree is badly affected

A tree with silver leaf throughout the canopy and brown staining reaching the main trunk is unlikely to recover. Remove and destroy the entire tree including the main root ball. Do not replant another Prunus species in the same spot for at least two years, and clear all infected wood from the area before replanting.