Photo and blurb by: Peggy Sellers, Purdue University
Perhaps you have seen brown galls like these on on red cedars and junipers. These galls are actually overwintering structures of the fungi (Gymnosporangium juniperi-virginianae or Gymnosporangium globosum) that cause Cedar apple rust or Cedar hawthorn rust, respectively.
Very soon, as the spring rains begin, bright orange gelatinous protrusions will emerge from these galls. These protrusions or telial horns produce spores that infect apples, crabapples, or hawthorns.
During midsummer, spores are produced from infected apple, crabapple and hawthorn leaves and these spores then infect junipers, completing the life cycle. The disease generally does not cause significant injury to junipers. For more information on these diseases and their control, refer to BP-35, Cedar Apple and Related Rusts.
Click on the small image to view a larger image.
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Plant and Pest Digital Library Project, Purdue University, West Lafayette, Indiana.