Silverleaf Fungus

Chondrostereum purpureum

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Mushrooms

Mushrooms

By Roger Phillips

Published 2006

Silverleaf Fungus Chondrostereum purpureum (Pers.) Pouzar syn. Stereum purpureum Pers. (illustrated 45% life size) Bracket 1.5–3cm×1–2cm across, 0.2–0.5cm thick, extremely undulate, usually several brackets fused together and overlapping; upper surface covered in dense, white, woolly hairs in concentric bands; lower surface dark violaceous or violaceous-brown in young specimens, becoming brownish with age, drying paler (lower specimens in photograph). Flesh tough when fresh, becoming brittle when dry. Spores 5–8×2.5–3¼, subcylindrical. Hyphal structure monomitic, generative hyphae with clamp connections. Habitat parasitic or saprophytic on various trees, especially members of the Rosaceae; all year. Common. Not edible.

This fungus is the cause of ‘silver leaf’ disease that leads to the destruction of fruit trees; plum trees are particularly susceptible. The first visible sign of infection is silvering of the leaves, due to the upper epidermis becoming separated from the rest of the leaf and lifting in patches. This effect occurs progressively along a branch, and on cutting the wood is found to be stained brown. The fungus can be eliminated if the wood is cut back to a point where no infection is seen and the wound is treated with a fungicide. Where silvering of the leaves occurs all over a tree simultaneously it is unlikely to be due to this fungus; this can be verified by examination of the wood for staining. This false silver leaf, which has the same symptom, that of the upper leaf epidermis lifting, is caused by physiological disturbance such as heavy pruning.

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