Your backyard apple trees can develop a number of diseases that can affect their fruit production and their appearance, including cedar-apple rust. Here are three things you need to know about cedar-apple rust.
What are the signs of cedar-apple rust?
This fungal disease is easy to identify because of the strange-looking fungal growths that develop on infected trees. These growths are orange and gelatinous and have numerous tendrils. You may think these growths look like sea urchins or octopi. In some cases, these growths drip an orange, jam-like substance onto the ground below. If you see this strange sight, you can be sure that your tree is sick!
Apple trees that are infected with this disease will produce fewer apples, and the apples they do produce will be lower quality. The infection also weakens the trees and lowers their resistance to other diseases.
How do apple trees get this disease?
Cedar-apple rust has a complicated life cycle that requires the infection of both apple and cedar (also called juniper) trees. Cedars become infected in the late spring or early summer, and, in the second year, they develop galls—the aforementioned orange growths—on their twigs. These galls produce spore horns and release fungal spores into the air, where they make their way to nearby apple trees.
Once the apple trees get infected, they release fungal spores in June or July, and more cedar trees get infected. This process continues year after year.
How can you control cedar-apple rust?
To control cedar-apple rust, you'll need to address your cedar trees as well as your apple trees. When you see galls developing on your cedars, remove the infected parts of the twigs and branches right away to protect your apple trees.
If your apple trees are already infected, carefully prune away the infected tissue. You should cut the branches at least two inches away from the galls; there's no need to remove the whole limb.
Systemic fungicide should be applied to the infected trees. Spray the entirety of the trees, including the trunk and the leaves. It's also a good idea to apply contact fungicide to the other apple or cedar trees on your property as a preventative measure.
If your apple trees—or nearby cedar trees—have cedar-apple rust, contact a tree service like ISA Texas Chapter for advice on what to do next. This disease can ruin the appearance of your backyard trees and harm their fruit production, but it can be treated.