Powdery mildew is a disease that can infect all types of plants. It forms a white or gray powder on a plant's leaves that is made up of fungal strands. It grows on the outside of the leaf. For this reason, spraying with an anti-transpirant such as Wilt Pruf may prevent infection. This coats the leaves making it hard for the strands to get a foothold.
Powdery mildew can infect both wet or dry leaves, making it the only leaf disease active during dry weather. The spores are spread by the wind.
Providing good air circulation around and through a plant (by pruning) will help prevent powdery mildew. It responds well to organic sprays as long as you are persistent in applying them. Use copper , sulfur, or Serenade. Please call or stop in for help with your particular plant!