Questions like this really require photos to illustrate the problem. Without them we are just guessing. And usually incorrectly :-))

Include your geographical location as well.

To prove gg’s point: Rust (“ … like a rusty red”)

This is a photo of the leaf and I am in Connecticut on the

Additional photo

I have Coral Drifts and they do quite a bit of that towards the second part of the season. Maybe it's iron insufficiency?

Not a iron deficiency. That presents completely differently.

It almost looks like a scorch or burning. Have you sprayed the rose with anything other than water?

No but, it's been about 2 weeks since my husband watered the flower beds and the temps here have been in the 90's. Can it be saved?

Was someone in the vicinity exuberantly slurping a nice raspberry smoothie?

denial or not. its september... its fall.. and the plants are going to get uglier.. and uglier until they go dormant and drop all their leaves ...

there is nothing to do to stop that.. and imo.. i dont treat leaves that will fall off in a few weeks... and we dont worry about them either ... its natures way ....

full fall cleanup get rid of yucky leaves so they dont winter over under the plants..

note all the highfalutin technical terms... lol

all this can happen earlier than norm based on all the insults the plants suffered since emerging in spring.. late cold.. hail .... winds.. drought.. high temps..etc... you do the best you can with whatever ma nature throws at your plants.. and when you both get tired in fall.. you put them to sleep for winter ...

ken