Pale yellow spots appear on the leaves and fruit in mid- to late spring. These spots gradually enlarge, turn orange, and develop minute black dots. Small cups with fringed edges form on the lower surfaces of leaves. Infected leaves and fruit may drop prematurely. The fruit is often deformed.
Cedar-apple rust cannot be controlled on the current season''s foliage and fruit. The following spring, spray trees with a fungicide labeled for this disease, following label instructions. If possible, do not plant crabapples within several hundred yards of junipers or red cedar. Infestation can take place from junipers as far away as 3 miles.