On apple or crabapple trees, it looks like round yellow spots on the leaves right after they bloom. Later in summer, brownish clumps of threads or tube-shaped things show up under the spots on the leaves, branches, or fruits.
The disease lasts for a while. Bumps show up seven months after it starts. They become jelly-like masses after about 18 months. Then, they get little holes like golf balls and grow telial horns in the next spring. When it rains in spring, the brown horns get longer and turn orange. After they let out their spores, the horns shrink, dry up, and drop off. Even though the bumps die, they stay on the tree for at least another year. The infection is easiest to see in spring when the bumps are covered in jelly-like masses.
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