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Symptoms: Orange, jelly-like galls with long horns (finger-like projections) appear on branches in the spring. Photo by Plant Disease Clinic |
Cedar apple rust and hawthorn rust, caused by two different fungi, need to infect juniper or eastern red cedar and an alternate host to complete their life cycle. The most common alternate hosts are apple, crabapple, and hawthorn. |
Symptoms: Orange, jelly-like galls with long horns (finger-like projections) appear on branches in the spring. Photo by Plant Disease Clinic |
| Causal organism: | Cedar apple rust: Gymnosporangium juniperi-virginianae Hawthorn rust: Gymnosporangium globosum |
| Over wintering: | In plant material (Juniper species) |
| Months of infection: | July-September |
| Method of dispersal: | Wind |
| Infection point: | Leaves and stems |
| Control: | Remove the alternate hosts when possible. Remove orange galls on juniper branches in late winter or during dry periods. Properly water, fertilize, and mulch trees. |
| Labelled fungicides (First application) |
Copper, Bordeaux Mixture, Bayleton, or thiophanate-methyl (Cleary's 3336) (July) |
| Comments: | Cedar apple and hawthorn rusts do not usually cause serious harm to junipers. The spermagonial and aecial stages form on the alternate hosts, apple, crabapple, and hawthorn. The telial and basidial stages form on juniper species. (see Cedar Apple Rust on Apple/Crabapple) or (see Hawthorn Rust on Hawthorn) |
| For additional info | Back to Juniper/ E. Red Cedar Diseases |