Silverleaf of Fruit Trees

a disease of fruit trees (apple, pear, plum, cherry, apricot) that is characterized by the silvering of leaves or certain affected branches. The disease manifests itself in midsummer. The most frequent cause is slight freezing of the wood and the consequent water and mineral starvation of shoots and leaves. Silverleaf is often accompanied by invasion of the tree by the fungus Stereum purpureum, which develops in the trunk and roots. The fungus excretes toxic substances that rapidly decompose the leaf parenchyma. As a result, air cavities form under the cuticle, creating iridescence of the leaves. The disease spreads to individual branches and, later, throughout the entire tree. The fruits of diseased plants develop poorly, fall prematurely, or do not develop at all. The wood turns brown and, with severe infection, dies.

Control measures includes increasing the winterhardiness of plants; protecting trees from sunscald, winter sunscald, and frost cracks; timely covering of wounds and treatment of cuts; and removal and burning of affected branches. Silverleaf disease that is caused only by freezing of the wood is treated by abundant watering, top dressing, and cultivating.