Why Does My Apricot Tree Have Silver Leaf Disease?

Silver leaf is one of the most serious fungal diseases affecting apricots, plums and related stone fruits in the UK. Caused by the fungus Chondrostereum purpureum, it produces a distinctive metallic silver sheen on the leaves of affected branches. If not caught and removed early, the disease kills branch after branch and can destroy the entire tree. There is no chemical cure — prompt surgical removal of infected wood is the only management approach.

Identifying silver leaf

The leaves on an affected branch develop a distinctive metallic silver sheen — not silver dust on the surface (that would indicate mildew) but a silvering of the leaf tissue itself caused by a thin air layer forming between the upper and lower leaf surfaces. Later, flat, leathery purple-brown brackets (fruiting bodies of the fungus) may appear on the bark of dead branches in autumn. Cut a 1–2 cm section from an affected branch and examine the cross-section — infected wood shows a brown or purple-brown staining in the centre. Unaffected wood is clean white or cream. This internal staining is the definitive test.

How infection occurs

Silver leaf fungal spores are released from the brackets on dead wood from autumn through to early spring. They infect through fresh pruning wounds, frost damage, and any other wound in the bark. This is why pruning stone fruits in autumn and winter is so strongly discouraged — the combination of fresh wounds and peak spore release creates ideal infection conditions. Prune only in dry summer weather (June–July).

Surgical removal

Cut back all infected branches to at least 15 cm below the point where the internal brown staining ends. Disinfect tools between every cut. Apply wound paint to all cut surfaces. Burn or bag all removed material — do not compost it. After successful removal, the tree may recover fully if the main trunk is unaffected. Check the main trunk and scaffold branches by cutting into them — if staining is present in the trunk, the tree is likely beyond saving.

After infection

Monitor the tree over the following two growing seasons. If new symptoms appear on previously healthy branches, repeat the surgical removal process. Healthy, vigorous trees with good nutrition and drainage resist silver leaf better than stressed trees.