The message said "this season", so I took that to mean that even early on this season as well as now this has been a problem, not just during the heat. Of course that was my assumption, and I normally get into trouble when I assume things. So we have to get more information and ask if this was a problem early on and have they been watering enough and in the San Diego area is heat stressing the plants? And we don't know if these roses have been fertilized at all, nor do we know if they have not been watered properly. So yes, zuzu could be 100 per cent correct, but still I suspect not enough fertilizer could also be the problem, that's my story and I am sticking to it(until Mark619 replies and blows my theory).