Looks like Rose Mosaic Virus (RMV)... if a rose has it, the splotching may only show when the plant is stressed. So you're probably right...the heat caused the symptoms to express themselves. Some say that RMV greatly reduces the cold hardiness, vigor, and other things. Some people just ignore it. :)

I could also be wrong...happens a lot. LOL

You would have seen RMV in the spring, not now. Where is it on the plant? Are all your bushes showing it? If it's just on the lower leaves on the plant, it could just be the natural senescence of the older foliage as the days get shorter.

If its the older foliage, then I agree that its likely end-of-season senescence, possibly exacerbated by stressors. If so, nothing to worry about.

Looks like RMV to me, which in my experience, can occur any time during the season, though it is more prominent in the spring. Diane

My first thought was same as Paul’s, just old leaves aging out. This would be the case if the yellowed leaves are at the bottom of the plant. If it’s new growth, it’s a different problem.

My guess is spider mites. My #1 enemy in hot & dry California. But since Carla has been gardening in California for many years, I would assume she knows spider mites symptoms.

It's a 10 year old tree rose, it's affecting almost every leaf, and it was sudden onset this month, I've never seen before, doesn't look anything like spider mites or virus.

I just noticed the Easy Does It tree rose next to it is starting it too! ( second photo)

I do recycle my bath water via a hose moved around to sections- could it be too hot water temperature on the roots?

Carla in Sac

I'm still looking through Internet articles and photos but I'm wondering if your rose is being affected by some sort of rust.

I’ve had roses’ foliage turn yellow rapidly when there too much water or bad drainage. A surprising amount of foliage turns yellow rapidly.

Thanks Magpie

My Blue Girl does have a bad case of rust, but you can see the pustules on the back on her. I did look carefully on the backs here, and included a back photo, but no pustules anywhere. So I'm thinking NO (but maybe they will appear later?)

Carla