I gave away all my roses last year before moving, but in the year leading up to that I treated them with tebuconazole which is a systemic fungicide, and Physan-20, which is a topical fungicide. I did so at least 3 times that I remember and I was shocked at how dark, green, and healthy all the growth was all year. I'm hesitant to say I didn't see any blackspot because technically it probably was there, but I did not expect it to be reduced as much as it was.
Previously I had tried neem oil a million different ways but I gave up on it because it's only minimally-to-moderately effective in areas with humid summers. I've never tried to Volck stuff. I don't know that I've even heard of it until now...
