Grower Guidelines: Controlling cedar-apple rust on apple trees

Cedar-apple rust is caused by the fungus Gymnosporangium juniperi-virginianae. To complete its life cycle, the fungus must infect apple or crabapple and an alternate host. Alternate hosts most commonly include native red cedar (Juniperus virginiana) and Rocky Mountain juniper (J. scopulorum). In the spring, orange jelly-like horns