Kari A. Peter, Ph.D.
The disease is caused by Podosphaeria oxyacanthae, one of the common species of the powdery mildew group of fungi.
The more common diseases found on currants and gooseberries are anthracnose, leaf spot, and powdery mildew. The most common virus disease is currant mosaic.
This disease is caused by Podosphaera clandestina, one of the common species of the powdery mildew group of fungi.