View All May 13, 2016

Found on the Greenway: Cedar Rust Gall

by Jim Bogenschneider, Catawba Master Naturalist


I was walking around Lake Crandall last summer when I spotted this golf ball sized gall on an Eastern Red Cedar tree that turned out to be a Cedar Rust Gall. I decided to document this gall as it went through its life cycle, from a dimpled brownish ball, to a gelatinous mass, and finally a black dried up end that will eventually fall off the tree. It takes about 7 months for the galls to form and 18 months to sprout the gelatinous masses.

Cedar Rust Gall (Gymnosporangium juniperi-virginianae) is a fungi that infects cedar, apple and crab apple trees. After the spring rains have caused the gall to turn into an orange gelatinous mass, as seen in the second photo, and the spores have found their way to the apple trees, rust colored spots form on the upper side of the apple leaf. If rain continues to be heavy the rust will progress quickly and the underside of the leaf will develop raised orange structures, from these the spores are released and the cycle starts again. While this rust on the apple tree does cause some damage it rarely kills the tree. At one time the Eastern Red Cedar was considered an invasive plant and was removed from, and around apple orchards.

As always I can’t wait to get out again and see what nature is up to and what else can be found on the Greenway.