Have you used potassium silicate for prevention of powdery mildew? It was a recommendation as a preventative and I am not familiar with it. I did find this info for a specific retail brand.

http://www.pqcorp.com/literatu...

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.

Thanks Zuzu. Now to figure out what brands are sold in Canada and where