Milk is more useful against mildew, but it is used against other fungi. Buy some copper sulfate and spray a solution of it over the roses, not before plucking off all affected leaves. If left only the stem, spray it! I've just found a fungicide with difeconazole base which has been very effective, in case you want to try the chemical way.
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I haven't tried that but whatever you do don't compost the leaves with blackspot. Burn or brown waste bin to protect the rest of your roses!
Milk is more useful against mildew, but it is used against other fungi. Buy some copper sulfate and spray a solution of it over the roses, not before plucking off all affected leaves. If left only the stem, spray it! I've just found a fungicide with difeconazole base which has been very effective, in case you want to try the chemical way.
Thanks wonky womble and dimwit ,I have sprayed them so we will see !