Possibly they are talking about Blackspot when disease resistance is mentioned? Someone on HMF mentions the drifts are prone to powdery mildew, straight after praising its disease resistance :)

http://www.helpmefind.com/gardening/l.php?l=2.45370&tab=32

I dont have any of the drifts, but I do get a lot of PM.

PM can kill or weaken a rose, but I wouldn't be cutting off branches...its not just in the soil, its in the air..everywhere! It tends to be related to how much humidity and the temperatures, usually early spring and fall are worst, (cool wet weather) but it dies off in summer. Some years are better than others, but some roses are just more susceptible than others.

Some people have success preventative spraying with milk and water mixtures- I just wait until the weather warms up, then trim off the nastier looking leaves, or if the plant gets it consistently and keeps looking bad, throw it out and try and select a better variety next time.

Curcle is right, typically when I talk about "disease resistance", I mean blackspot. For this time of year, don't do anything. I'm with cecily, leave it be. It might get it again in the spring, but usually PM doesn't last long here, and I have never had it kill a rose.

Powdery mildew is not as lethal as black spot. It usually starts appearing from the top down on the newer growth, where as black spot starts from the bottom up on the older growth of the bush. Cold nights and warm days coupled with dry, rainless weather encourages the growth of powdery mildew. Wet weather is hard on PM, and can be counted upon to help control it. I know a rosarian who sprayed his PM afflicted roses twice a day, AM and PM, with water alone, no fungicide, and effectively halted the PM in its tracks. Spring and fall in our climate, NJ and PA, have very similar growing conditions, hot days coupled wth cool nights, are the powdery mildew seasons.

PM, as stated earlier, is not as harsh a disease as is black spot. You can go for years with no outbreaks and almost overnight it can hit, not to return for several more years. Powdery mildew is sneaky, it appears subtly, some slighty misshapen newer growth that is mild, then bingo almost before your eyes it turns into a full blown case. It severely disfigures the foliage and buds, suppressing their development. An outbreak this fall does not mean your roses are from this day forward PM prone. PM is in the environment and really needs very specific conditions to manifest itself, conditions that are not present every spring or fall every year.

I believe some rose varieties are more susceptible to PM. Those with dull, matte leaves being prime targets, with shiny leaved roses being more PM resistant. There are probably other susceptibility factors, too, but the foliage finish is the major one of which I know. Hybrid rugosas, as tough as they are, are PM susceptible, probably due to their dull finish foliage and rugose, pebble grained, texture. The nooks and crannies being perfect breeding grounds for the PM fungi.

What to do? You have several choices:

1. Spray with a fungicide, organic or otherwise.

2. Spray twice a day, AM or PM, with plain water, wetting the foliage down. However this method may promote black spot!

3. Do nothing. It is now very late in the season, roses are slowing down and very soon to be dormant. The PM on the roses will not be a factor in the spring of 2017. Remember, PM is ever present in the environment, waiting for the perfect conditions to infest our roses. Fortunately the specific conditions it needs to be an outbreak are not easily met in our climate, thank God.

One last thing, PM in the spring needs to be dealt with by some means. In the fall, the upcomming winter stops it dead in it tracks. Therefore, a hands off, do nothing approach, may be your wisest action at this time.

thanks for this post moses, but what should be done now.?.my some very healthy ones otherwise newer roses are full of powdery mildew..I don't spray at all..cant do water am pm as I am in pnw , a bs magnet...any other options or i shall just spray?

R,

I believe spraying is necessary at this time.

The Bayer fungicide works great for black spot for me, but powdery mildew, although not frequently encountered, when it is, it is hard to get under control with the Bayer product. It works, but not quickly. After the third weekly spray, real progress is seen.

Spectracide's Immunox, without fertilizer, is reported to be specifically more effective against powdery mildew than the Bayer Fungicide. I have not yet tried it.

There are organic fungicides like Bayer Serenade. My niece reports that It is not particularly working for her, but I am not sure she is spraying correctly or regularly. I have not used organic fungicides to date.

If you decide to spray, give the Immunox a try.

Moses

Dilute hydrogen peroxide seems to have some effect when I tried it last year.

My Winchester Cathedral is constantly battling PM. It is so irritating. It is such a beautiful rose but that PM is on my last nerve. Tonight it will be getting a milk bath.

I had Peach Drift & it got BS....not impressed with the disease resistance of the Drift series in my area.

Try spraying (or dipping if it's a smaller pot) it in very hot water. A University study showed this worked well. Kristine's suggestion of spraying with a dilute milk spray also works well. I had this on my Red Drift when it was a distressed sale rose and had read it was slightly prone to it. However, it responded well to the hot water dunk and hasn't ever gotten it since ie. two seasons and counting.

Drift Roses have always been a problem for me. I read that they are specifically suseptible to cercospora leaf spot. In my experience they look good long enough to sucker you in and then the leaves start to look crappy. I came to the conclusion its better to stick with antique roses rather than be swayed by the latest trend.