If you can keep the leaves dry, the fungus won't spread as easily. Keep removing the affected leaves, even if your shrub looks stripped, and keep on the spraying regimen. Clean up fallen leaves completely. If you haven't beaten the problem by next dormant season, I would prune the shrubs down low, give them one last thorough spray, spray the surrounding ground area, and cross my fingers. If black spot survives those treatments, I would remove the infected shrubs to protect your other rose bushes. Good luck.
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