Problem: Powdery Mildew (Boston Ivy)
This plant disease is caused by the same fungus (Uncinula necator) that causes powdery mildew on grapevines. The powdery patches consist of fungal strands and spores. The spores are spread by wind to healthy plants. The fungus saps the plant nutrients, sometimes causing the leaves to yellow and die. Under favorable conditions, powdery mildew can spread rapidly through a planting. Powdery mildew is generally most severe in the late summer and under humid conditions.
This disease is usually not serious enough on Boston ivy or Virginia creeper to warrant treatment. Keep the leaves dry if possible.