Photinia Shrub black spot
HI. Thank you for your question. This fact sheet describes the disease and suggests fungicides that can be used. https://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin011/odin011.htm
Rake up and dispose of the diseased leaves to reduce the potential for infection for next year. infected leaves can be a source of spores when weather conditions are just right for disease development.