Cedar Apple Rust

  The fungus spends part of its annual life cycle in apple and crabapple (Malus species) and part of it on juniper, which are primarily eastern red cedar (Juniperus virginiana) The most frequently noted symptoms are bright red-orange-yellow spots on apple leaves in the summer. Junipers susceptible to cedar-apple rust develop pea-sized to 2-inch diameter spherical growths (galls) on infected needles and twigs. During prolonged wet periods in the spring, the juniper galls secrete orange-brown gelatinous horns (tendrils). In the spring, gelatinous tendrils erupt out of mature galls on infected junipers. If possible, avoid growing susceptible junipers close to crabapples and apples. Most basidiospores infect apple trees within a few hundred yards of the juniper host, however basidiospores infect a fair number of apples as far as a mile away. If replacement is an option, grow cedar-apple rust resistant varieties of Malus. Resistant to very resistant varieties of apples include: Delicious (red), Empire, Keepsake, Liberty, McIntosh, Milton, Niagara, Paulared, Regent, Spartan, and Viking. In addition, there are a number of resistant crabapples such as Adams, Candied Apple, Chestnut, Dolgo, Kelsey, Sargent, Snowdrift, and Thunderchild.

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