I Found Some Brown, Round Bubbles on My Cedar Tree: What Are They?

Cedar Apple Rust

• Cedar apple rust is a fungal disease that is caused by the pathogen Gymnosporangium juniperi-virginianae. Symptoms of the disease include brown, round bubbles that emerge of the cedar tree's leaves.

Brown Galls

• The brown, round bubbles that emerge on the cedar tree's leaves are known as galls. Galls are a collection of fungus and plant tissue, and the galls often grow to the size of a half dollar.

Reproduction

• During the cedar apple rust's reproduction phase, the galls become smooth and dimpled and take on a chocolate brownish color, especially in the winter. In the spring, the galls sprout two orange horns that contain a gel-like substance. The horns serve as a reproduction center, emitting millions of fungal spores into the air. The spores are then distributed on neighboring plants. The life cycle of the disease is 24 months long from the time of infection to the death of the galls.

Management

• Cedar apple rust rarely damages the overall health of the tree. Management involves making sure the two host tree species are not planted near one another. In extreme cases, fungicides are applied due to loss of foliage.