Trees may seem impervious to damage or disease because they are so big and resilient, but the smallest organism can weaken a tree and even kill it if it grows unchecked. If you have spotted black mold spots on your tree, act fast to keep your tree healthy and mold-free.
Inspect the tree for black mold and make note of every affected area. The mold may be on branches or leaves, so check both. It may have a smooth or a powdery surface.
Prune the tree with sterile shears. Wipe the clippers down with rubbing alcohol in between each cut. Remove all affected branches and leaves. Dispose of the plant material in a sealed plastic bag. Pruning allows more light into the center of the tree, which will help kill off any mold you miss.
Rake all plant material from underneath the tree to prevent reinfection. Dispose of the plant material in a sealed plastic bag.
Spray the tree down with neem oil. Cover the tops and bottoms of the leaves as well as the bark and branches. This will kill small insects, which are likely the source of the black mildew, and prevent reinfection.