Silver leaf

Chondrostereum purpureum

A silvery sheen spreads over leaves of plums and cherries, followed by branch dieback. Prune stone fruit only in summer, when infection risk is lowest.

Fungus Serious Airborne sporesSpread on tools & hands Spreads to neighbors

What you'll see

Leaves on one branch take on a metallic silver sheen, which then appears on more branches each season.
Cut through an affected branch and there is a dark brown or purple stain in the center of the wood — the only certain diagnosis.
Branches die back progressively, from the tip and from the affected side of the tree.
Small flat brackets, purple beneath and buff above, form in overlapping tiers on dead wood a year or so after death.
A tree may throw off a mild attack and re-leaf normally, or may lose limb after limb.

Why it happens

A fungus whose airborne spores enter through fresh pruning wounds and other wood injuries between autumn and early spring. It grows in the water-conducting wood and releases a toxin that lifts the leaf surface away from the layer beneath, and that trapped air is what makes the leaf look silver. The silvering itself is a symptom in the leaf, not fungus on the leaf.

Damp autumn and winter weather, when spores are released in quantity and wounds heal slowly. Trees pruned in the dormant season, or damaged by wind or frost, are the ones that catch it.

Treating it

Cut out affected branches to at least 15 cm beyond the last stained wood, into clean white tissue.
Do this in June or July, in dry weather, and sterilize the saw between cuts.
Burn or bin the prunings so the brackets never form and shed spores over the garden.
Keep the tree well mulched, watered in drought and sensibly fed; vigorous trees frequently outgrow a mild attack.
If the trunk shows the stain, the tree cannot be saved — take it out along with any dead stumps nearby.

Keeping it away

Prune plums, cherries, apricots and other stone fruit only between late spring and midsummer, never in winter.
Make small, clean cuts to the branch collar and avoid tearing bark.
Remove dead wood and old stumps from the garden, since these grow the spore-bearing brackets.
Avoid heavy renovation pruning of old plums; take a little each summer instead.
Protect trees from mechanical damage and keep them growing steadily.

Who gets it

Plums and cherries above all, with apricots, peaches, apples, hawthorn, poplar, laburnum and roses also taken.