We recently received this picture from Franchise Owner John David Andrus in Opelika, AL. He came across these bright orange, gelatinous-looking growths hanging from an arbor vitae on his property. He knew that what he was seeing was the gall from a disease known as Cedar-Apple Rust, but he never had seen the galls up close and personal.
Cedar-Apple Rust is an interesting disease as it requires two different plants to complete its life cycle. On the cedar. Juniper or arbor vitae.
The disease develops a gall that is somewhat round, about the size of a golf ball, brown in color and has dimples on it. During the wet weather of spring, the galls will swell and produce gelatinous tube-like structures or horns.
These structures will produce spores that are picked-up by the wind and moved on to susceptible apple or crabapple trees. These trees will develop small, yellow spots on the leaves soon after the leaves open. They will enlarge and become a bright yellow-orange color.
As mentioned earlier, this disease requires both an apple and a cedar or juniper tree to complete its life cycle. On an apple or crabapple tree, the infected leaves may prematurely drop. In late summer, small tube-like growths form on the undersides of the leaves. Spores from these structures are released and travel by wind back to susceptible cedar or juniper plants.
This disease’s life cycle takes two years to complete. One year it infects a cedar or juniper and the next year it infects the apple tree. Even though it takes two years to complete the disease life cycle, the disease can infect the same tree every year as many trees can be infected and the wind can carry the spores of the disease up to two miles.
There are control products that can be applied to stop the spread of the disease, but the trees should be sprayed every year. In most cases, the material should be sprayed when the flowers are beginning to drop their petals in the spring and when the leaves are beginning to unfurl.
If you have the proper equipment, you can do the work yourself. Just make sure you remember to read and follow all label directions before using any control products. However if this is not something you feel up to tackling many people find that it is easier to contract with a lawn and tree care company. For more information contact your local Spring-Green office.