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.

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

I would just point out that neem oil has excellent fungicidal properties and is frequently recommended for good, organic rose care. It is suggested for use by the American Rose Society to control diseases like powdery mildew, black spot and can even have an impact on reducing the incidence of rust. One just needs to realize that it is only a preventative fungicide, not a curative, so of most benefit before the plant becomes highly infected. But it will limit the spread of any fungal disease to unaffected foliage. Just avoid spraying during the heat of the day - early morning or late evening. My current garden in the woods is too shady to grow many roses but when I did, I swore by Rose Defense by Green Light, which is clarified hydrophobic extract of neem oil. It did a great job of limiting any fungal issues as well as for common insect control. btw, it also works on insects other than just soft bodied ones by disrupting life cycle functions like eating, molting, mating and egg laying. It also acts as a repellent and has been effective against Japanese beetles. And it is 100% organic and OMRI approved. It was the only pesticide I used on my roses!!

louislinus You have a beautiful house. I love your gorgeous stone-walkway. The above pic. (white rose) has a green rose slug. Rose slugs (sawfly larvae) infest roses in poor-drainage clay. You have lots of Walker's low blue catmint, which thrive in heavy clay here. The second pic. (from the top of your post) shows lots of holes in leaves, besides black spots. I also see rose-slug damage (brownish-latticed leaves). Holes in leaves are typical of slow drainage dense clay in heavy rain. I used to get holes in leaves right after heavy rain, then I moved roses and found water could not drain fast in that spot. Roses that like fast-draining like Queen Nefertiti is most susceptible to rose-slug and holes in leaves. I fixed the soil with fast-draining coarse sand, dug out all the rocks below, and NO MORE green ROSE SLUGS. Do you have dense clay soil? If so, then poor-drainage is a problem in mid-west heavy rain. I would check for drainage: dig a hole near the MOST black spotted rose, pour a 5 gallon bucket of water down that hole. If the water doesn't drain within 10 min, any rose would black spot in that area during heavy acidic rain. pH of rain in Midwest area is 4.5. With my 134 varieties of roses, black spot is no longer a problem once I check the planting hole for fast drainage by pouring a 5-gallon bucket of water, before planting a a rose. If the water doesn't drain fast enough, I keep digging and often I would find large stones that block drainage. High Country roses recommend digging a hole 3 feet wide and 2 feet deep. But I often dig deeper than that to check for stones. A quick fix to slow down the heavy & acidic rain is to pile up horse manure (the type with wood-chips, rather than hay). Hay is acidic, but sawdust/woodchips decomposes to alkaline. There's a poor drainage spot where I dug down 2 feet and found water .. but Golden Celebration (black spot-prone) was 100% healthy. I piled up ALKALINE horse manure (with wood-chips) up to 1 feet tall. When acidic rain at pH 4.5 poured down, it was instantly neutralized by that pH 8 horse manure. Stable here deodorizes horse manure with shell lime (high in calcium & high pH). Calcium is the best buffer against acidic rain. The LEACHING of calcium is what causes holes in leaves after heavy rain. Once the leaves are thinned out with acidic rain, they are more susceptible to rose-slugs (green sawfly larvae). I never have rose slugs in the years with horse manure, despite poor drainage clay. In the years of topping roses with horse manure (pH 8), zero black spots in raised beds, and very few leaves with black spots in poor-drainage clay. (posted plenty of pics. in Organic Rose forum). Besides calcium, horse manure has anti-fungal trace elements (zinc and copper) to thicken leaves. Pics below are my roses with horse manure, note the THICKER foliage. Decades ago I saw the same flawless foliage in a neighbor who used horse manure & same with another garden with horse manure. From that time on, I started topping roses with horse manure. I don't spray.