Infected leaves are covered with a white powdery material. When disease is severe, infected leaves can be distorted. Benomyl can be used for the control of this organism, however, control is not generally necessary. The fungus enters through broken limbs or through insect tunneling. In advance stages the interior of the tree will be a soft, spongy yellow or brown mass.
Perennial cankers are bracket to hoof shaped.
The upper surface of the fungus is dark brown to black while the underneath is a dull reddish brown. Control is not recommended. Rust attacks the leaves causing a distortion of the leaf mid vein. It is most often observed on the first leaves in the spring. Damage is usually not significant and control is not required.