The Purdue Plant and Pest Diagnostic Laboratory

What's Hot on April 21, 2006
at the P&PDL!

Cedar Apple Rust--One of Nature's Spring-time "Decorations"

Gail Ruhl, Sr. Plant Disease Diagnostician, Botany & Plant Pathology, Purdue University

The bright orange gelatinous galls with tendril-like protrusions known as telial horns are signs of a fungal disease known as Cedar Apple Rust.  The telial horns of this fungal pathogen, Gymnosporangium juniperi-virginianae, 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 of this rust fungus.  The golfball-size galls that form on eastern redcedar are unsightly, but usually cause little harm to the tree. During dry weather, galls can be removed and destroyed.  For more information on this disease please refer to BP-35, Cedar Apple and Related Rusts.

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Photos courtesy of Jim Peter, Dubois County Extension Educator

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Cedar apple rust

Cedar apple rust

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service