Photinia Shrub black spot
What to use to eradicate black spot on Photinia plants
Sussex County Delaware
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.