Shot hole, also called Corenyum Blight, is a fungal disease that infects trees by causing lesions on buds, leaves, twigs, and fruit. This fungal disease flourishes during long wet springs, or warm wet winters. During the winter, it grows inside of trees and infects twigs and buds. As the fungus continues to grow, the leaves turn raggedy and fall. As a result, the tree will be unable to perform photosynthesis leaving it stressed to the point where it becomes more susceptible to insect attacks. Since this fungus is very hard to control, the best treatment would be to apply a preventive fungicide.
Take a look at what Kevin Caldwell, Owner of Caldwell Tree Care has to say about treating this issue in this new video.