White powdery, often circular patches appear on the leaves, stems, and flowers. Leaves may be covered with the powdery growth. This material usually appears first on older leaves and on the upper surfaces of leaves. Tissue under the powdery growth may turn yellow or brown. Sometimes such leaves drop from the plant.
Remove infected leaves. Move plants to locations with more light. Keep plants out of cool drafts and in rooms with temperatures as even as possible. Do not crowd plants together.