That is not how my rose leaves respond to lack of water or too much sun.

Too much spray? Too much fertilizer (nitrogen)?

Just suggestions. I don't really know.

Kate

I have had that sometimes on some of my albas and gallicas. This year Felicite Parmentier has quite a bit of it now late in summer, while newer growth appears healthy. Luckily most of the plant have green leaves. I think it is a form of blackspot or crud that turn out this way in some types of roses. Nothing to do really, other than not using too much artificial fertilizer. Good compost and adding stuff like seaweed in the soil tend to strengthen the plants. I only have it some years, other years not a trace of it until late in September. When autumn comes I see it in the leaves that fall off.

Old garden roses with damask or portland ancestry can show similar symptoms when they have a bad case of blackspot fungus. Do you know the name of your rose? If your plant is growing actively, do you find the symptom or the older or the newer leaves?

Looks like a particularly virulent case of bs.