seedlings with PM

This year I have a great PM problem with my seedlings of 2009.

Many of them I had killed. Other had only a few or not PM.

But after 4-8 weeks after starting PM I had sprayed.

Now the next PM “wave” arrive the seedlings.

Some peoples said next year the seedlings with PM will not have a PM problem. I should not kill the PM-seedlings.

What is your experience about seedlings with PM?


I live in the San Francisco Bay Area, which has an enormous mildew problem. 95% of my seedlings have mildew bad enough to distort the leaves and twist the stems, unless they have Baby Love or Home Run in their parentage. I have tried to keep those seedlings that had great blooms, but I have not found that mildew goes away the next year. Therefore, I throw away all severely mildewed seedlings immediately, and throw away moderately affected seedlings a few months later.

Hi Andrea,

I would say that 75% of my seedlings get PM. But I found that most of them do not have it the next year. I try to get my seedlings in the warm morning sun so they can absorb the heat and that helped alot. I then would move them in the shade about 1:00-2:00 in the afternoon.

If I threw out every seedling that got Mildew in its first year of life, I would be tossing out 99.5% of my work. Disease immunity is something that builds up as a plant ages. In my case, to get my seedlings through their first year I must rely on an occasional application of fungicide. Its only from year two onwards that plants start having to prove themselves without as much of my help.

Most of my seedlings spend their first year in a greenhouse. I spray a fungicide as little as I can get away with to keep Mildew down to minimal. Working under plastic is far different from working out in the open air. A plant that gets Mildew under plastic might be superbly healthy when grown outdoors. Case in point: ‘Knockout’ mildews badly when grown in a greenhouse.


Knockout mildews badly outdoors here. I live in the same climate as Gail, and my experience with mildew and seedlings is the same as Gail’s. A seedling with serious mildew never outgrows it in this climate. It might get better in a different climate, but I don’t keep seedlings that aren’t healthy here.

Thank you, for the information.

I don`t have a greenhouse.

I sprayed the seedlings.

The seedling have morning sun.



Gail is right that seedlings with ‘Baby Love’ or ‘Home Run’ in them tend to be cleaner with respect to powdery mildew. While it is true that seedlings that have mild cases of mildew will grow out of it, I wouldn’t waste too much time on seedlings having more mildew than that.

One benefit for being hard on your seedlings is that you will ultimately clean up your breeding stock so that instead of having 75% to 95% of your seedlings getting powdery mildew, you can reverse that to about 25% (or better). When I first started growing seedlings in the greenhouse, nearly all of them would get powdery mildew (even ‘Sexy Rexy’ gets powdery mildew in my greenhouse). Now with all of my breeding stock having ‘Baby Love’ or ‘Home Run’ in them, the majority of my new seedlings have no powdery mildew.

Jim Sproul


I had both powdery mildew and downy mildew invade my tiny greenhouse this winter. Every single plant in the greenhouse had mildew (except the wild-rose crosses), but none of them died of it. In mid-April I planted all the seedlings outside. Since then it has been very wet, and some of the seedlings are still/again heavily mildewed, but most of them are clean now and doing fine. I think baby roses are like baby humans; they overreact to every disease that comes their way! Next year, I’m sure all of them will be fine.



last year the seedlings had PM. I hold the best seedling

(with only a few PM). This year the seedlings are healthy.

This year I have seedlings from a cross with a PM-resistent rose (pollen parent). These seedlings have only a few or don´t have PM.

In Germany you can´t buy Baby Love or Home run.

Perhaps you can order Baby Love in UK.

But I think I can find other PM resistent roses.