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.

Where do your roses grow? What has the weather been for the past month that is different than May weather? Are the roses Hybrid Teas?

The one on the left is caused by "rose slugs" that are inch worm like bugs that eat the underside of leaves, leaving a thin film that no longer is green, but gray. The bugs are often less than an inch long and are often a light yellow green in color. Second leaf from left probably has the fungus anthracnose, also called buckshot fungus, round black damage that has gray centers, some of which fall out,,,,thus the name . I'm not sure what's eating the edges of that leaf. Third leaf from the left is old and ready to drop off. there may be another problem, but I'm not sure. Fourth leaf from the left has some anthracnose, and possibly another fungus, but it would take a microscope to confirm the second fungus. Hope this helps, Ann

This is the 3rd year for my roses and they have hardly bloomed at all. There is black spot and general malaise. 😂 We also had Japanese beetles but I think I’ve gotten rid of them. You can see some are doing better than others. I’m new to roses and not sure what to do. I’ve read a bunch of different information on how to get rid of black spot but not sure which tactic to take. Any other tips you have are much appreciated. I’m in zone 6a. These are mostly David Austins.