Powdery Scab

Powdery scab (Spongospora subterranea) is a fungal blemish disease of potatoes. The “powder” is comprised of spore balls (cystosori) that are released into the soil and can survive up to ten years. These release motile zoospores that infect root hairs. Powdery scab is also a vector of Potato Mop Top Virus, a cause of spraing.