The fungus over-winters in diseased plant debris on the ground and on the dormant shoot buds. Powdery mildew infection appears as slightly raised, blister-like areas on young leaves. The leaves are soon covered with a grayish-white powdery fungal growth. As leaves expand, they become curled and distorted. On older leaves, large white patches of the fungus appear without much leaf distortion.
Flower buds covered with the fungus either fail to open or open improperly.
The infection may spread to mature flowers and cause a flower blight. Crapemyrtle cultivars released in recent years involving Lagerstroemia fauriei in their parentage are resistant to powdery mildew. These cultivars are noted in the table. Cultivar selection is an effective way to control the disease. Cultural methods for controlling powdery mildew involve sanitation procedures and applying fungicides.