I also buy mancozeb under the Bonide label "Mancozeb Flowable with Zinc". I have used the mancozeb once every 3 days for 9 days on existing blackspot. Then use it once a week for the next 4 weeks. Then I alternate Bayer and mancozeb every couple weeks. It did the trick and did not spread to other bushes, although I was sure to spray all my roses and the ground surrounding them because the bs can be there but not visible yet. According to the folks at Rosemania, mancozeb is the treatment of choice if the bs is already visible and to use Bayer as a good preventative. I live in Missouri and we have hot and humid summers. My neighbor's roses get blackspot...but not my roses.

Both sulfur and copper can burn rose foliage. Be sure the plants are well hydrated and spray in the morning. Don't apply copper on a drizzly day--it is less likely to burn if it dries quickly. Don't use sulfur in very hot weather. I've used the copper soap product Soap Shield successfully. Wear standard PPE when applying copper products.

I think I found a possible explanation for what I've observed often enough to keep bringing up that I don't strip on the first sign of leaf infection. If this does explain it (or if it's a good theory anyway), then it does seem to have to do with my choice of roses or the aggressiveness (lesion expansion rates) of the local strains of BS here. From http://www.rosehybridizers.org/Fall_2012_Zlesak_long_version.pdf "...We have blackspot resistance field data for the roses that are designated Earth-Kindî in the South Central US. As we correlate the mean lesion size in the lab with the percentage of defoliation due to blackspot in the field, r=0.62...So in this case there is a pretty strong trend that as lesion size goes up for a rose in the lab, the more defoliation we see for that rose in the field. Since different isolates of different races can be more aggressive and lead to different lesion expansion rates, it is very promising to see such a strong correlation in the midst of that variability. As more blackspot resistance data are collected from other ongoing Earth-Kindî trials involving some of these 70+ roses, it will be interesting to revisit the correlation between the laboratory and field data...." And the RHS has seen what I'm talking about, so at least I don't feel so crazy ;) http://apps.rhs.org.uk/advicesearch/Profile.aspx?PID=270 "Typically, a rapidly enlarging purplish or black patch appears on the upper leaf surface, with diffuse and radiating strands of the fungus sometimes just visible. Leaf tissues may turn yellow around the spots and the leaf often drops, even though other parts are as yet unaffected. At other times, the yellow colour does not appear, but infected leaves still drop. Sometimes, the spots remain relatively small and the leaf does not drop. [!]" I'm not trying to tell anyone how to do anything if it goes counter to their local experience, of course. I guess I'm saying that folks might wait a bit and see what happens if they don't strip leaves if the plant will be very defoliated if they did strip so many leaves that don't look too bad. See what happens, perhaps. Or not :) Here is a link that might be useful: Strategies and resources for breeding blackspot resistant roses, DAVID C. ZLESAK

Blackspot is a plant disease caused by wind borne fungus spores in water drops.They land on the top of the leaves and when growing looks like circular black spots with irregular edges. The infected leaves will finally turn yellow and drop off. If the disease is severe all the leaves will drop off and the plant will have to grow a new set. The quality of the blooms will suffer and the plant will be weakened. Blackspot can not be cured but it can be controlled. In climates where there is a lot of rain in the summer or high humidity it becomes more prevalent. Blackspot can be controlled best by spraying with a dormant oil and sulphur spray in the early spring before the bush leafs out. Then again in the early summer using at half the strength. There are also other ways to keep it control. Clean up all dead and fallen leaves, water when the sun will dry the leaves off or use drip or soaker type hoses, remove first six inches of leaves from the ground up so splashed water won't jump the spores on the leaves, plus feed and water plants well as a weak or stressed plant will succumb more quickly . Finally choose varieties that are disease resistant.