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Cedar-apple rust and other similar rusts

Quick facts

  • Do not plant trees, shrubs or other plants in the rose family (including apples) close to juniper and cedar.
  • Plant disease resistant varieties when possible. 
  • Cedar-apple rust (along with hawthorn, quince and juniper broom rusts) requires two different hosts to complete its life cycle; one plant from the cypress family and the other from the rose family.
  • The rust fungi rarely cause serious damage to their hosts and usually do not require management.

The rust fungi, known as Gymnosporangium, cause unique and fascinating diseases that require two different living plant hosts in order to complete their life cycle.

The bright red and orange leaf spots and orange gelatinous galls that are signs of these diseases draw a lot of attention. But the disease rarely causes serious damage to its hosts and often does not require management in a home landscape. A few highly susceptible plants may suffer shoot death or lose their leaves.

Do not plant any plants from the rose family (Rosaceae: apple, crabapple, chokecherry, cotoneaster, etc.) near juniper and cedar trees or shrubs. 

Identifying rust

These diseases require two different plants in order to complete their life cycle. Symptoms are very different on each type of plant.

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Managing rust

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Rebecca Koetter and Michelle Grabowski, Extension educator

Reviewed in 2018

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