MichaelG posted a formula to treat botrytis a few years back that worked wonders. The chemical base was calcium nitrate or some other form of soluble calcium if I remember well. It had to be sprayed on the rose blooms before they opened. Worked like a charm, the material was cheap and not dangerous like Daconil or the extremely expensive stuff like Degree (??). The best compound is not available here in the south but for those in the north who still have snow can be bought now because it is used for melting snow - I just cannot recall the name, since I never saw it here. Maybe calcium sulfate? (???) Michael, if you have the article or the summary handy, would you be kind enough to re-post it? I know that I saved it somewhere but it will take time till I find out where.

Hi Esther, I can't think of any bicolored varieties that are anywhere near as Blackspot free as the ones I have noted. However, there is a possibility that 'Magic Carousel' might do well in your region. The climate conditions that affect severity of Blackspot infection is different in NY then it is in coastal OR, so 'Magic Carousel' might be great in your area. Here, it does lose some foliage from disease, but many growers report that it is one of their best selections, so it might be worth trying. As I mentioned earlier, the grocery store mini roses were bred for greenhouse cultivation, not the open garden. It is highly unlikely there is anything you can do, cultivation-techniques wise, that will improve their resistance to Blackspot. If you have found that sprays won't control the disease, then you would be best to relegate these plants to a windowsill where they won't get their leaves wet, ever or just chalk it up to a learning experience and toss them out.

The following was stated: "Henry, I do not want to get into an argument over the validity of sources." I am not questioning the validity of a source when it was written. I am pointing out that 2 reviewed scientific research papers have been published later that invalidate the 2 statements that I selected (for roses). For those interested in this area, the link below is to: "FINAL RESEARCH REPORT TO THE CERES TRUST FUND, January 2017 Title: Unraveling the mystery of compost teas used for organic disease and insect pest management" From a scientific study done at Michigan State University from 2011-2016. https://cerestrust.org/wp-content/uploads/schilder-final-report-jan-2017.pdf Please note that they did not specifically study roses.

Thank you for bumping up this thread, Marlorena! Hi, Claire. I'm on the other coast, in Portland, Oregon, but it sounds like you and I have had similar success with certain cultivars of old roses. Portland is also the blackspot capitol of the universe. I'm not sure if the disease strains in our two areas are identical, but the roses that you mention as resistant are ones that I also find to be resistant. I can live with the level of blackspot where I'm required to pluck a few leaves, but the only rose that completely defoliates that I tolerate (so far) is the Austin rose Abraham Darby. Like you, my garden is no spray. Period. Teas do get some blackspot here. One of the healthiest for me has been Duchesse de Brabant. Her blooms also stand up fairly well to moisture. Other Teas that have been relatively healthy for me are Madame Joseph Schwartz (the sport of DdB) and Mlle. Franziska Kruger. I just received an Odee Pink from the Antique Rose Emporium. I've grown it before and found it to be pretty healthy, too. Portland's hotter, drier, extended summers are making my Teas happier...even though the gardener is not-so-much happy. If you love Mademoiselle de Sombreuil, I'd try her. I'd protect her when young and perhaps try to keep her canes protected from wind in the winter. Maybe grow her on lattice so she gets good circulation while foliage is growing, but somehow place a screen several inches behind her in the winter. I used to create gardens for clients with all kinds of crazy sites, like high rise balconies. Talk about winter wind! I have a couple of metal trellises I've covered in bubble wrap and have used to block wind. You must stabilize them so they don't fall. I've used umbrellas over roses that dislike soggy blooms or young plants that need shade. My theory is, if you really, really love a rose, there's probably some way to make a home for it. Greenhouse anyone? :-) Bourbons: I have grown the Bourbon Souvenir de la Malmaison, and she was tolerably healthy for me. I think she's worth a try. Her blooms dislike moisture, so growing her under an eave or on a porch can really help. I've had success with Zephirine Drouhin and Honorine de Brabant. Madame Isaac Pereire was a blackspotted nightmare...all three times I grew her. Like banging my head against the wall repeatedly, I thought each time would be different. MIP's fragrance is heavenly, though! Totoro, If you really want her and wish to try her again, I'll bet MAC will grow just fine for you once she's established in the ground. She's one of the toughest and hardiest Noisettes. She's no Marechal Neil or Gloire de Dijon. Mine is planted on a French drain. I know! Really?! Carol