Two hosts are required for the fungus to complete its life cycle. Distinctly different spores and symptoms are produced on the deciduous and evergreen hosts. Spores produced on the rosaceous host infect only juniper plants and those originating on the evergreen host infect only rosaceous plants. Overall infection of cedar-apple rust. Spore production and release are favored by wet weather during May and June.
Orange spots develop at the point of infection on the rosaceous host.
Gall formation at the point of infection does not become evident until July the next year. The galls increase in size until that October and become fully mature the next spring when they produce teliohorns under favorable weather conditions and start the cycle over again. Two years are required for the fungus to complete its life cycle. As they mature, galls become reddish brown and their surface becomes dimpled, resembling a golf ball. These tendrils may shrivel during dry weather but can expand again during and shortly after wet periods several times in the spring.