Can you take some photo's of the affected blooms and put them on here?
I have some roses that ball quite often this time of year, as you said, it is mostly caused by thrips. They should stop balling now that it's heating up. As the thrips seem to disappear, also as you noted, during the hottest time of the year, and I generally don't have problems with thrips in the fall. Generally the first flush on some of my roses ball, but after that first flush they return to blooming beautifully. My worst roses for balling on first bloom are Ginger Hill and Clotilde Soupert.
Alan
