After doing some research, I'm thinking it might be the sudden hot weather we've had. We had a very, very rainy spring and early summer and this week is the first our temps have really hit the 90s. We just had heavy rain for a couple of hours yesterday afternoon, though... so I wouldn't think they'd be suffering from being too dry??

Regarding diagnosis: one approach would be to respray just one of the roses, and observe. To test the hypothesis that liquid fence was the cause. I most recently heard a discussion about formulating hypotheses on Dinosaur Train, an excellent TV show. By Scott, the paleontologist. A good step in the US playing catch-up in STEM.

Haha rifis...so true!