Trees, Shrubs and Conifers: Red-Tipped Photinia in trouble, 1 by DebinSC

DebinSC wrote:
Two weeks ago I noticed a small area of our photinia looked bad. It was at the same time as the annual azalea caterpillar invasion and the damage was similar, so I suspected it was insect damage.

However, the caterpillars are gone and over the past few days the damage has spread significantly to almost a third of this very large shrub.

Here is a photo of it. On the left you can see the way the whole thing used to look.

I'll follow up with a close-up.

If you know what this is, please let me know. This is a beautiful plant and I'd be very sad to lose it.
Thanks!!
Deb