So, I'm into year two of my rose-heavy gardening obsession and I'm discovering a new & unpleasant fungal disease that I did not seem to have issue with last year for whatever reason, and that is Powdery Mildew. Last year my arch enemy was blackspot, and after observing it for a year & reading lots of articles & forum posts, I feel like I'm fairly comfortable with understanding it & dealing with it. However, this Powdery mildew stuff just confuses me. Right now it is only affecting a few plants, all of which are new to me this year, but all of which I've read in one place or another were pretty healthy, disease resistant plants. I know this really depends on conditions, but since most of my other roses are thriving with no issue, I'm just wondering if it is these types or if it's me.
The main offenders are: two different Madame Alfred Carrieres (from two different scources), a Cramoisi Superior (perhaps the worst offender), Duchesse de Brabant (not one of the worst but still bad-supposed to be an earthkind rose), and Souvenir de la Malmaison (the least affected).
I understand that PM can become more of an epidemic if the plants are not getting enough water, so I've been out watering like a fool, sometimes daily, which seems to have no affect. I've read you should strip affected foliage, no affect, I've read you could even spray with milk or sodium bicarbonate, still no affect. As soon as new growth appears it just gets covered, even if I've already stripped all affected foliage AND sprayed one of the above mixtures. I'm just wondering if these plants were just not meant to live in my climate, or if it's something that I'm doing wrong. I live in the hot & humid east tennessee valley & like I said, this is the first I've seen of powdery mildew, aside from a couple of crinkled leaves here and there last summer. All of the affected roses are in pots, which might be a contributing factor, but because they are in pots I water them about every other day, because they are in an area that receives a lot of sun. About 20 other roses in the same conditions are thriving, but these few seem to just do nothing but mildew. I've tried moving them to an area that receives morning/early afternoon sun only, thinking maybe almost-full sun was too much, but there was no change.
The two MAC's arrived close to the same time from their different scources, and my plan was to plant one here and one at my father's house, and when the first plant started showing signs of PM, I started babying both of them (while keeping them seperated) and eventually the second one came down as well, and now they are both miserable with it.
CS has been the biggest problem child though, it seemed so healthy when it arrived from ARE, but it was in my possession for only a few days before I noticed the first signs of PM, I stripped off the affected foliage, sprayed, it came back full force, and after a few more strippings, sometimes spraying sometimes not, now it is just a bucket of twigs that occasionally produces new growth, that I try in vain to protect. I wonder how much more it can take of this.
The DdB & SdlM are surviving, but it seems like they are not outgrowing it, or the pace of their growing is equal to the pace of their dying off....
Do any of you have any advice for me? Or should I just give up on these few? I am really hoping I can save the Duchesse de Brabant and Souvenir de la Malmaison, but I think that Cramoisi and Madame Alfred may just not be worth it? It's just hard to say since I don't yet understand why they have had such a hard time.
michaelg
jerijen
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