Hi there,

Thank you so much for your question.

It's hard to diagnose exactly what's going on with your Photinias without a picture and more information about your soil, ect, but I can tell you that they are very susceptible to a range of issues including root rot and fungus.

The fungus will typically cause some red spotting on the leaves. Have you noticed any of that? I've included links to a couple of articles that provide more information.

https://neilsperry.com/2016/05/question-of-the-week-may-5-2016/

https://pnwhandbooks.org/plantdisease/host-disease/photinia-leaf-spot

To get a solid answer you may want to consider sending a sample in to the Texas Plant Disease Diagnostic Lab. Their email is <personal data hidden>. Here is a link to their submission form: https://plantclinic.tamu.edu/files/2010/10/Plant-Disease-Diagnosis-Form-D-1178.pdf

Hope this is helpful!