Hi, Joanne. I don't have to fight powdery mildew anymore now that I've taken out the old ramblers, which were the only roses that ever got it here, but I read the information just out of curiosity. It sounds as though this stuff works on the same principle as Messenger, which everyone used to rave about so much before it became unavailable: It's supposed to boost the plant's natural defenses. Sounds good to me.
