The best control is to plant resistant varieties. Page 337 of the Ortho Home Gardener Problem Solver lists rose varieties resistant to black spot, powdery mildew, and rust. Most are black, brown or dark red. They typically mine between the bark and sapwood, starting a flow of pitch or boring dust called frass. Management entails appropriate cultural practices to ensure healthy trees.
Irrigation is especially important.
Avoid root and trunk injuries and protect from sunscald. Prune off infested limbs and remove and dispose of dying trees so that insects do not emerge and attack other trees. Use the taste test. Pick what you need and leave the remainder on the tree for storage. Ripening time varies with each variety.