Cedar-Apple Rust,Gymnosporangium juniperi-virginianae
Pucciniaceae or Puccinia Rust Family

Mushrooms on red cedar host

A parasitic fungus with a complex life cycle, alternating between two different hosts, eastern red cedar (Juniperus virginiana) and apples or crab apples (genus Malus). Other junipers can substitute for the eastern red cedar, and quince or hawthorn can substitute for apple. On the red cedar it forms a hard woody gall with circular depressions (below left and center). After a rainy period gelatinous orange horns containing spores grow out from the depresssions. At this stage, it resembles an orange octopus that has somehow climbed the red cedar. If spores from this stage land on an apple leaf or blossom they can infect it, producing a bright yellow spot with colored rings around it on the leaf or fruit. From this infected spot short tubular galls emerge later in the season and release a different kind of spore that can infect red cedars if it lands on a damaged needle or twig.

Not uncommon in Wildwood, where both hosts are common.

Rarely noticed since only the short lived orange octopus stage is particularly striking. If seen at this stage, however, it is hard to miss and easily identified.

Gall stage

 Closeup of gall


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