Silver leaf is a serious disease for plums but it can infect many of the Rosaceae family. Including apple, apricot and cherry trees, Rhododendron species and Laburnum species. Though the disease is called Silver leaf, this symptom mainly appears only on plums when they are infected. Other stresses such as cold and drought can also cause similar symptoms, this is termed false silver leaf. The darkening of the bark is a definitive way to identify silver leaf from the false form.
Leaves have a silvery sheen. This usually starts in one place and spreads down the tree. As it progresses, leaf margins and around the midrib may split and turn brown. The wood of infected branches turns a dark colour which is one of the ways to determine if it is silver leaf or false silver leaf. After this discolouration, the branches start to die back. During the summer after branches have died, Small bracket-shaped fruiting bodies form on the bark. The disease will often spread through the whole tree and kill it if it goes untreated.
Poor soil conditions, poor air circulation.
Silvery sheen to leaves (mainly in plums)
Darkening of bark
Dieback of branches
Lilac bracket fruiting bodies
Some trees can get over it by themselves. No need to destroy leaves as they do not carry the fungus. If branches begin to dieback then remove them and burn them. If the whole tree has silvered that means that the whole tree, including the roots is infected and should be uprooted and burned to prevent further spread.
There are no chemical treatments.
Spores from the fruiting bodies infect trees through wounds in the wood they do not infect the leaves. The spores are most active between September-May (UK). The fungus produces toxins that are taken up through the tree which causes the leaf tissue to separate, air then enters the leaf which causes the silvery sheen.
Good hygiene around plants e.g. clearing dead material from tree bases. Not over fertilizing. Having good drainage. Pruning in late spring-summer rather than autumn or winter is recommended as this when the infectious spores are produced. Growing resistant cultivars.