Description: There are numerous fungi that fall under the general description of a powdery mildew. Powdery mildew appears as a dusty white to gray coating over leaf surfaces. In most cases this fungal growth can be partially removed by rubbing the leaves. The fungus is favored by periods of high relative humidity or site conditions that promote a more humid environment, such as close spacing of plants, densely growing plants, or shade.
Organic Control: Products that contain neem oil or potassium bicarbonate are effective, organic controls for many plant diseases.