Diplocarpon mespili is the type which infects photinia and many other members of the rose family.
Diplocarpon rosae is one of the fungi which results in black spot on roses. "No Spray Rose Cultivars for the Mid South"

I agree :-) Not a plant that does well in this climate. Almost impossible to find one that is disease free. And once they contract the leaf spot, they have it forever and just get more and more unsightly.

A lot of better local independent nurseries have stopped selling it here.

They are very old and very big. I only want to deal with them if they are a problem for my roses.

No. Photinia and roses are in two separate subfamilies and the leaf spot is generated by two different organisms as well. One should have no affect on the other.

oursteelers, cutting down my photinia was a sheer delight! They were horribly pruned totally blocked all light to the ground and so grown together in one mashup - the branches did not fall after they were cut. They were the first to go when we moved into the house and now hydrangeas, ferns, beesias and other beautiful plants are happily growing in the space.

With it growing over 30' tall Fraser photinia was doing fine in this climate until the leaf spot showed up.

Ophoenix, if I could wave a wand and the photinia would disappear I would do it. But they are so big and... I don’t know it seems like there are so many other things to do in the yard that I just put that out of my mind

With its comparatively large leaf size and strongly colored new growth Fraser photinia is generally not that great of a background shrub anyway. (Of course, there are specific plants it goes well with, when healthy, and as part of mixed planting. Rather than when present as a hedge or otherwise forming a setting against which it is being attempted to make a variety of plants show up well).

roseseek:

I followed the link you provided (above).

I found it interesting. But how did it relate to either the statements above the link, or to the OP’s question?

It was part of the black spot information. The asked about family of fungi causes one of the strains of black spot. I thought someone might have benefited from the information. If not, I apologize.

Roseseek,

I found it very interesting - thanks for the link.

You're welcome. I'm glad I could help!