May. Later, cluster cups are evident on the underside of the leaf spot. The fungus that causes this disease also produces galls on juniper. Plant resistant varieties . Although eradicating junipers is not feasible, removing galls from nearby junipers may be of some benefit. Avoid planting crabapples adjacent to junipers.
Fungicides can provide good control, with proper timing.
Make the first application when gelatinous, orange tendrils are noticed on the cedar galls, usually in mid-April. Continue the applications on a 7 to 10 day interval as long as galls are active. New shoots appear as if scorched by fire. Plant resistant varieties . Prune in late winter or late summer or fall, not in spring.