The disease that you have heard about does exist. It is called Entomosporium and it affects both Indian Hawthorne and Photinia. It is killing these plants over their entire planted range, and it spreads quickly because there are so many of these plants in landscapes. There are costly sprays that will help to control the disease, but they are usually too costly for most homeowners and home associations to afford. There are some cultural practices that you can use to keep the disease from spreading. Avoid overhead sprinklers in the areas where these plants are planted. Splashing the diseased leaves will disperse the fungus spores and can lead to further infection. Remove all diseased portions of the plants in the landscape and destroy the debris. Choose alternate plants when the time comes to replace the dead plants in the landscape that are resistant to this disease. There are more disease-resistant varieties of Indian Hawthorne on the market, and the old-fashioned Chinese Photinia has shown to be more resistant to this disease. Other suggested alternative plants include Abelia 'Kaleidoscope', Dwarf Nandina, 'Sizzling Pink' Fringeflower or 'Knock Out' Rose for the Hawthorne, and Wax Myrtle, Yaupon and the Chinese Photinia for the Red-tip Photinia.
Thanks for your inquiry.

Happy Gardening!
The PlantMaster