Cedar Apple Rust
The causal agent of Cedar Apple Rust is the heteroecious basidiomycete Gymnosporangium juniperi-virginianae. By definition (of heteroecious) this rust fungus require two hosts to complete its life cycle. Cedar (members of the genus Juniperus) usually have the most visible symptom of the disease in the early spring as the orange gelatinous teliohorns are produced. Basidospore produced in these teliohorns are blown to susceptible apple trees where they germinate and infect. iIn late summer, after subsequent spore stages, aeciospores are blown back to the cedar where they infect and galls are initiated where they grow and mature the next year. In the spring following a year growth on the cedar, the galls give rise to teliohorns and the cycle is complete. It take two years to complete the disease cycle.
The most common host of Gymnosporangium juniperi-virginianae. in Nebraska is eastern red cedar (Juniperus virginiana). Other susceptible alternate hosts include; Rocky mountain juniper (Juniperus scopulorum), creeping juniper (Juniperus horizontalis) and common juniper (Juniperus communis).
Copyright (C) 2008 J.E. Partridge, University of Nebraska-Lincoln. All Rights Reserved.
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