Mike said:RpR, why not just spray the leaves with a little bit of fungicide as a preventive than pouring gallons of fungicide into the ground?
Black Spot is in the debris on the ground, heavy rain it splashes back up on the plant and if you do not do some thing to remove it (including removing all debris on the ground , if possible, it will be there year, after year, after year , after year, after year....
I blow away the remaining leaf debris that I use to cover my roses every year, and usually douse the plants in spring before I add Cocoa Bean hulls for mulch then if I see, start, I pick the leaves off and douse the soil again along with treating the plants.
Cocoa Bean hulls, two to three inches deep, keep the ground from splashing up but some times BS come out of now where probably the wind or as I said, I have had newly purchased plants that bring it with them.
If you read my post in Norther Gardens about the now all but extinct Munsinger Rose Garden in Minn., you can see what Black Spot unchecked, along with not dealing with the ground they grow in, can do to a very large garden.
I did not put it in that post but two years ago I was there and spoke to a gent working there about the Black Spot that was running rampant and he said the lady in charge would not allow them to use ANY sort of commercial disease control on the roses.
