Those interesting structures are cedar apple galls and represent one part of a disease called cedar apple rust. Susceptible cedars and junipers are varieties of eastern red cedar and Rocky Mountain juniper. The other part of the disease is the alternate host, a susceptible apple or crabapple variety. The galls are not aesthetically pleasing, but they do no harm to the tree. You can prune them out on small cedars and junipers in late winter or very early spring. Control with fungicides is not warranted. Although not destructive to cedars, cedar apple rust is devastating to apple, crabapple, quince, and hawthorn, spreading disease spores up to 4 miles. Be a good neighbor; prune these masses out and destroy them.

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