Have you noticed an odd element in your cedar trees recently? If you see something about the size of a tennis ball that appears to be covered in strings of orange jelly, you are witnessing evidence of Cedar-Apple Rust. Before they “bloom” into alien-looking maturity, they appear as small, warty knobs a little larger than a nickel. With their dimples, these galls look a little bit like brown golf balls.
Cedar-Apple Rust is a common fungus in the southeast, especially in warm, rainy weather. To survive, the fungus must spend part of its life on apple trees and part on something in the Juniperus family. In the south, that is typically Eastern Red Cedar. The fungus cannot survive without both hosts (apple/crabapple and something in the juniper family).
While unsightly, the fungus balls don’t have a major impact on cedar trees. Apples, on the other hand, develop round rust-colored spots on the leaves. The younger the leaves, the more susceptible the tree is to airborne spores. A tree can lose a majority of its leaves in serious infestation. Fruit is dotted with dark spots that damage appearance and quality.
If you want to include an apple tree in your home landscape, be sure to select a cultivar that says it is resistant to Cedar-Apple Rust. You can reduce the impact on cedars by removing the jelly balls, but many of them are held in the upper branches of trees, outside of safe reach. It takes two years for the fungus to mature, so you can reduce future problems by removing galls when they are in the hard, warty stage.