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Cedar-apple rust and related rust diseases

Quick facts

  • Cedar-apple rust and related rust fungi need plants from two plant families to complete their life cycle; Cupressaceae family (eastern red cedar and other junipers) and Rosaceae (apple, hawthorn, serviceberry).
  • Bright orange to red leaf spots occur on apples, hawthorns, and other plants in the Rosaceae family.
  • Hardy woody galls, witches brooms and swollen stems covered in gummy, orange, fungal growth in spring occur on juniper and eastern red cedar.
  • These fungi rarely cause serious damage to their hosts and do not require management in most cases.
  • This disease can cause damage to leaves and fruit of very susceptible apple varieties, but is only a minor problem on resistant or partially resistant trees.
  • Do not plant eastern red cedar and juniper within a few hundred yards of apples, hawthorns, and other plants from the Rosaceae family.
  • Disease resistant varieties are available for some plants.
     

How to identify rust

 
4 pictures of different symptoms of rust.

These diseases require plants from two different families in order to complete their life cycle; one plant from the Cupressaceae family (red cedar, juniper) and the other from the Rosaceae family (crabapple, hawthorn, serviceberry). Symptoms are very different on each type of plant.

Signs and symptoms

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Rebecca Koetter and Michelle Grabowski, Extension educator

Reviewed in 2019

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