Apply all pesticides according to directions on the label. The disease spreads from the cedar to the apple and then back to the cedar. It can be a severe problem wherever these two are grown together, and most ornamental crabapples and apples are susceptible. This disease has raised spots on leaves that are bright orange-yellow. Leaves and fruit can drop from the tree.
Severe defoliation can lead to reduced bloom the next season.
Spots develop primarily on the leaves in mid- to late spring. Infected fruit is often small and distorted. On the Eastern red cedar, hard brown galls up to 2-inches in diameter form near the ends of branches in the summer. In the spring following a rain, the galls produce large, orange, gelatin-like tendrils, full of spores, which can blow up to a mile to infect nearby apple or crabapple trees. If possible, remove red cedars from the area or prune out galls on nearby cedars.