Paeony - control botrytis or mildew

I have many herbaceous paeonies and each year I have some that get a fungus that will either start rotting the base of one or a couple stems. Other times the plant has developed all its leaves and them some of them start to turn black. When this happens, I cut them off and discard in the trash (cleaning pruners after). The ones that have rotted at the base, I have cut them off below the soil surface.
I have been treating them with a bordeaux solution when this happens to try and control it? Have made sure that they have good air circulation.
Not sure if there is anything else I can do or am I treating them with the right product?

 

I think the bordeaux must be used before the symptoms of botrytis appear. Common practice is to apply a spray of bordeaux or fixed copper as the plants emerge from the ground, repeating in a few weeks. Don't know if it is available in Canada, but there is a new organic fungicide, Serenade, that is labelled for botrytis.