Excellent explanation Lyn, thank you! The varying reports I read about resistance to disease around the country had made me wonder. Our night temps nearly always drop well below 85, and often see heavy dew, so it makes sense. I find it very much trial and error, but do find many that are vigorous and clean here. Failures are simply opportunities to try other Roses, there are certainly more out there than I'll be able to trial in my lifetime, LOL.
