Cedar-apple Rust Gall - Gymnosporangium juniperi-virginianae

"Gymnosporangium juniperi-virginianae" is a plant pathogen that causes cedar-apple rust. In virtually any location where apples or crabapples and Eastern red-cedar coexist, cedar apple rust can be a destructive or disfiguring disease on both the apples and cedars. Quince and hawthorn are the most common host and many species of juniper can substitute for the Eastern red cedars.