This disease is caused by the fungus Gymnosporangium juniperi-virginianae and requires both cedar and apple trees to survive each year. It is mainly a problem in the eastern portion of North America and is most important on apple or crabapple (Malus sp), but can also affect quince and hawthorn. The chief damage by this disease occurs on apple trees, causing early leaf drop and poor quality fruit. On apple, symptoms first appear as small green-yellow leaf or fruit spots that gradually enlarge to become a yellow-orange color. On the lower leaf surface and sometimes on fruit, raised hair-like fruiting bodies appear. Wet, rainy weather conditions favor severe infection of the apple. On cedar, baseball-sized galls with bright orange jelly-like horns may form in the spring over large portions of the tree. Twig galls on the cedar may eventually die, but they often remain attached for one to two years. Although spores can travel several miles, infections between apples trees and cedar/juniper trees usually occur within a few hundred yards.