What Is Cedar-apple Rust?

Cedar-apple Rust, also known as Gymnosporangium juniperi-virginianae, is a pathogenic fungus that diseases and disfigures apple, Cedar and Juniper trees. On Cedar and Juniper trees it produces reddish-brown galls up to an inch in diameter that grows bright orange jelly-like horns containing spores for reproduction. Located below is a video clip of a Juniper tree suffering from this type of fungus.

Gymnosporangium juniperi-virginianae and Juniper tree.

Where Does It Come From?

This fungus will show up in any area where apples or crabapples and Eastern-red cedar trees coexist. This complex fungus uses two hosts during its cycle. The first warm rainfall in the Spring triggers the galls to produce its orange tentacles containing spores. These spores are transferred to apple tree leaves by the wind and the fungus then infects its second host.

Then around the months of July and August the fungus produces another set of spores that transfer it back to the Eastern-red Cedars to complete the cycle. Once back, it infects the tree and produces small brown swellings in the twigs the size of peas.

Get Your Tree Help

Cedar-apple Rust is not only unsightly but can be very damaging to the trees it infects. For help with diagnosis and treatment, contact us for a free quote.

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