Diseased weeping Japanese cherry
Cherry trees, both ornamental and fruiting kinds, are very susceptible to a fungus disease, Brown Rot and Blossom Blight of Stone Fruit. To help limit the disease, gardeners must spray during bloom -- at the popcorn stage, full bloom, and/or petal fall.
Sprays which can be applied by home gardeners include Bonide Captan 50 WP, Infuse Systemic Disease Control, Ortho Max Garden Disease Control, and Spectracide Immunox.
Copper sprays are discouraged because they can encourage the development of resistant disease organisms. Then, too, they have little to no effect on limiting the disease.
Sprays must be supplemented by targeted pruning designed to remove,and discard, all affected twigs and /branches during summer, when it's dry.
Another goal is excellent air circulation in and around the tree. Prune in such a manner that air can freely circulate throughout the canopy.