I have a row of "red tips" or photinia's and I'm having problems. See the photo below. The leaves look burned. Only thing I've done this year is feed them with Plant Tone about 6-8 weeks ago and then a little liquid fertilizer about 4 weeks ago.
I've got about 12-15 of them and most of them are starting to look like this. Any idea what's causing it and how to resolve it?