Often numerous black pimple-like fruiting structures of the fungus are found on the infected tissues. The best control now is to prune out the dead wood. In the case of C. sericea , rejuvenation pruning that removes the oldest stems is recommended. Keep plants vigorous. This black velvety fungus is not pathogenic but survives on the sugary sap that falls on the leaves.
Sooty mold indicates a sucking insect infestation.
In this case, scale insects were present. Identify the specific scale and control crawlers when they are active. Sooty mold will disappear once the scale population is under control. This disease is frequently found on nursery grown trees in garden centers and occasionally in the landscape. Sprays have to be applied as buds break and repeated at 7-10 intervals to control spot anthracnose.