Tree maintenance isn’t simply about mulching, pruning and watering our trees. It is also about checking them for insects and disease. One such disease is a common fungus that affects crabapple trees and fruit-bearing apple trees – Cedar Apple Rust. So before you plant an orchard of apple or pretty crabapple trees, ask yourself this: Is there a cedar tree lurking in my yard or neighborhood?
Cedar Apple Rust (Gymnosporangium juniperi-virginianae) is a fungal disease that needs both a cedar and an apple or crabapple tree to complete its two-year lifecycle. Initially, a gall develops on a cedar tree in the fall, then springs to life after the April rains, becoming a gelatinous, orange ball with tentacle-like appendages, releasing spores. These spores are carried by the wind to infect your crabapple or apple tree. Although the spores can travel up to five miles, the damage to your trees usually happens within a few hundred feet.
Cedar apple rust damage will occur on the leaves and fruit of an infected tree. Leaf damage includes yellow & orange spots generally seen one week post-bloom time. The spots grow in size and by mid-summer develop hair-like tubes on the underpart of the leaf. These tubes release spores that travel back to the cedar tree host. On the fruit of an apple tree, the spots are much larger causing inferior fruit and possible early fruit drop. Early leaf drop can also occur in infected trees – both apple & ornamental. Interestingly, the fungus cannot be transferred from cedar to cedar or crabapple to crabapple tree.
Can’t live without apple trees in your yard? Find apple tree varieties that are resistant to cedar apple rust. Redfree, Liberty, William’s Pride, and Freedom are examples of new apple varieties that are immune to cedar-apple rust. Already planted apple or crabapple trees and your cedar is infected? If the galls on your cedar tree are few and can be reached, prune them off and dispose of them in the garbage. Clean up any infected apple tree leaves and dispose of them in the garbage (and not your compost pile). Finally, think about choosing a different kind of tree to plant if you have cedar trees in your yard or close neighborhood.
So while you are mulching, pruning and watering your trees, take a peak at their leaves, trunk, bark and fruit to see if anything is a miss. Do the leaves have spots? Is there a large web with worms in the branches? Are there holes in the bark? Any of these can be symptoms of common insects or diseases that will affect the health of your beautiful tree. If caught early, you may be able to treat & save your favorite tree.