Rusts - Apple Cedar Rust

Gymnosporangium Rusts - (Apple-cedar rust, Juniper-hawthorn Rust)

Gymnosporangium Rust
Helen Atthowe, Missoula County Extension
Infections on Juniper and Cedar


cedar apple rust
Helen Atthowe, Missoula County Extension
Infections on Apples and Hawthorne

 
Rust occurs anywhere that perennial hosts (juniper, cedar, etc.) grow near their deciduous hosts(apple, hawthorn).



Orange leaf spots, defoliation and fruit and twig deformities. Juniper infections appear as swellings on deciduous host or galls on twigs, these form gelatinous orange fruiting bodies in the spring.

CONTROLS: Optimal temperatures for rust infections are 64-70° F. High temperatures (>85° F.) and dry weather discourage rust disease.

Cultural: Irrigate early enough in the day so that plant surfaces have time to dry before the cooler temperatures of evening. Keep irrigation off of leaves, branches, and trunk.

Prune plants for good air circulation.


Mineral: Sulfur sprays can be effective if sprayed preventatively in the spring when rust infection periods occur(wet with temperatures 60-70ºF).


Missoula County Extension Office; Missoula, Montana 59808 - Updated for 2006