I have always sprayed the roses with actin-ovate once a week to prevent the nasty's. Question: the new growth is so stunning, should I start now with the spray or wait till the nasty's start to appear?
As I was growing up my grandparents and parents always repeated a popular saying that, "An Ounce of Prevention is worth a Pound of Cure". That being said, I always start spraying my roses from the moment the leaf buds start to open and every 10 to 14 days (in my climatic conditions in Colorado) for the rest of the season. The Actin-Ovate is said to be a very good organic style fungicide, however if it does cause problems with discoloring of the rosebushes foliage or even perhaps some leaf burn issues, I recommend using another product in a rotation. I personally use one called Green Cure that is available on-line. I can use it without any foliage or bloom discoloration or any foliage burn of any kind. I use it at the Cure Rate listed on the label for longer lasting protection. Once the "nasty's" start to appear they have gotten a start on you that could be hard to get stopped or gain control over. Spray soon!
Stan The Rose Man :)