Here's a site with info and a pic. This should help you out.

http://search.aol.com/aol/imageDetails?s_it=rboxImgDtls&query=downy+mildew+on+rose+stems&img=http://www.huntingtonbotanical.org/Rose/resources/imagesspringlg/Downy%2520Mildew.jpg&host=http%3A%2F%2Fwww.huntingtonbotanical.org%2FRose%2Fresources%2Fspringinthegarden.htm&width=143&height=107&thumbUrl=http://images-partners-tbn.google.com/images?q=tbn:mlIAZNrnb4wuXM:www.huntingtonbotanical.org/Rose/resources/imagesspringlg/Downy%2520Mildew.jpg&imgWidth=800&imgHeight=600&imgTitle=...%20or%20understood%20Downy%20Mildew%20...&imgSize=192197&icid=snap-pic&flv=1

JIM

I see no powdery mildew in your images.

Powdery mildew is white, and it is on the leaves, peduncles, buds, and so forth. You can see it on a cane, but it's like a white powdery coating.

I can only go from your pix, but what I see in your photos looks like what has been diagnosed as downy mildew here.

There are chemicals that can be used as a drench for control. The local Farm Supply guys tell me that they don't work as well as they used do, but they are available.
I quit using them when one of them melted the surface of my plastic measuring spoon.

I PERSONALLY have achieved better control mulching out to the dripline with fresh horse manure, and watering regularly.

Jeri

Here is a link that might be useful: Powdery Mildew Images

Let me ask this: Which came first? The brown patches or the "mildew?" I cannot comment on what the fuzzy stuff is. I DO wonder if the mildew has shown up because the canes are cankered or if the canes are turning brown BECAUSE of the mildew.

The link I gave you above in my first post, shows pics and the difference in the two mildews. What you have is not very common in gardens... Downy Mildew

JIM

I was reading up more on Downy Mildew. It suppose to spread through a garden like wildfire. Yours didn't spread did it?
Hopefully, you do have something else, instead of Downy mildew. That stuff sounds nasty.

JIM

IIRC, downy mildews are much less common infections because they require persistent wet, humid weather over an extended period (weeks?) for the spores to germinate and the fungi to grow. IIRC, powdery mildew requires hot, humid, dry weather.

Check your local Agricultural sources in your area and do your best to find out what it is on your stems.
Most websites are recommending destroying the plant if it is Downy Mildew.
Best of luck!

JIM

I see why your confused to what you have on your rose stems... LOL I read many articles on Downy Mildew and the info varies very much with each aricle. Confusing!
I'm sort of lucky as I live 17 miles from Penn State. They are a wealth source on disease info if I ever need them.

JIM

I called my friend from Penn State and I e-mailed him your pics. He told me the only way to be certain exactly what it was, is to obtain that fuzz stuff you seen and an expert would have to exam it under a microscope. Any other way would just be guessing, as other diseases can mimic downy mildew.

JIM

Wow! You guys provide better info than the Master Gardener did. I am glad I did not stop there just because her ID. It just didn't seem right.

I am afraid ((sob)) it looks like Downy Mildew. All signs point to it, and that picture on the link Jim kindly provided looked just like mine. Except mine does not seem to have open lesions like that one.

-Jim, you are wonderful! You provided such a wealth of information. Thank you for taking so much trouble to help me!
I really was baffled by all the info I read on Downy Mildew. Most sites said it was rare to see it out side of a greenhouse situation, and really isn't a problem in gardens. A couple of sites also said that Downy Mildew will quickly defoliate a plant. My infected plants still have foliage, which I think is interesting. There are even some flowers on them.

-greenhaven, what came first were green 'water spots'. You know how when water dries on a leaf it will sometimes leave a slight trace left of where it was? That is what it looked like but under the 'skin' of the cane. It was still green, but had a sort of outline. These irregular marks darkened into the reddish-brown in my pic. The marks were slightly tough, like scabs. No swells, lesions, sunken, or shriveled areas. I scratched this area with my nail once and the fiberous stuff under the skin looked okay.
The first year it wasn't major, so I didn't stress over it (now I am, lol!). The second year was worse. I read up on it and started to look at it frequently in order to chart the growth/evolution of it. In the late fall the brown patches had white-gray fuzz on top, just like some sites said it would (in both Downy and Powdery Mildew cases).

I probably should have done something when I first noticed it, because it has spread to other roses. My DA rose 'Carding Mill' was the fisrt to get it. It was a weak grower from the time I planted it. Maybe stress/dislike for this climate made it prone to disease? Could it have been infected when I bought it? It didn't seem to show any troubles for the first year or two; can Downy live dormant for long periods of time? Anyway, the next to show the marks (run! its the plague! lol) was a scrawney 'Gold Medal', and then a brand new 'Windermere'. 'The Dark Lady' also seems to have it, but (knock on wood) it hasn't spread much on her. She seems healthy, and put on a good show in the spring. None of the roses infected seem to want to put on new growth after the first spring flush of growth.

Do you guys think I should try to save any or just trash them? I don't want it to spread, but I do hate to get rid of any.

I don't know if it is going to be possible for me to do, but where does one go to have a sample examined under a microscope? Back to the County Extension? Do you happen to know if it costs much?

I want to cry from frustration. This makes me want to give up on all roses...
CMK

There are many fungi that can infect rose bark, and usually it's not a big deal. I'm sure I and others answering this thread have lots of spotted green canes in the garden. I appreciate your careful observations, but your concern may be out of proportion to the scope of the problem. You have healthy foliage and flowers, so the damage done by the fungus may be superficial and not affecting the roses' circulatory system. If the bark dies and the canes stop supporting healthy growth, then you would just prune out the obviously bad wood.

The grayish white bloom might be downy mildew, but downy mildew is not normally downy on roses. It attacks the younger leaves and kills them, with dark spots visible and eventual yellowing. Leaves die soon and fall off. The disease spreads rapidly in cool, wet conditions and affects all varieties. DM can infect green bark, but I doubt it would affect bark without affecting leaves.

Do you live in semi-arid Western Washington with warm summers? DM can't be a chronic problem where temperatures often rise above 80 degrees. It is likely to be chronic in gardens only on the immediate Pacific coast where cool temperatures prevail year around. Now obviously I haven't experienced all these conditions, but I'm reporting what the scientific literature says.

A freind told me that I ought to check out the products at Gardens Alive, that they have a liquid Copper Fugicide that is suppost to rid roses of Downy Mildew.

Can Downy sucsessfully be controlled/eliminated with any type of spray/treatment? Has anyone ever gotten rid of Downy mildew in their gardens?
I am torn between working an uphill battle trying to save my roses and yank the infected ones before they spread.
CMK

It is likely to be chronic in gardens only on the immediate Pacific coast where cool temperatures prevail year around. Now obviously I haven't experienced all these conditions, but I'm reporting what the scientific literature says.

*** The scientific literature is correct.
Lacking cold or hot temperatures, our best control has been a healthy bacterial colony promoted by fresh horse manure as a mulch.
Seriously.

Jeri

-michaelg, sorry I did not notice your post earlier (or, more likely, it wasn't there then). So you don't think this is Downy Mildew? Powdery?

No, I live in Eastern Washington state, which is semi-arid. We do have fairly harsh (both cold and wet) winters and dry summers. Weather is volatile. It can be chilly and damp one day and the next hot and dry. My soil isn't the best either, though I am trying to amend it.

So Downy Mildew is only a seasonal disease? It goes away under conditions that do not promote its growth?

I also find it interesting that it does not show any troubles on the foliage. Most sites online note that foliage troubles is a sign of Downy Mildew. Are there various strains of DM that would infect only canes? I don't know if that is possible or not in roses (not an expert on them I'm afraid!).
Sorry for the many questions, but I like to be educated about these things. ;-)
CMK

I wrote "western" by mistake. I meant "eastern Washington."

In a semi-arid climate with cold winters and warm, dry summers, it's very unlikely you would have any experience of downy mildew unless you brought home an infected potted plant in the spring-- which is fairly unlikely, although there are sometimes outbreaks in rose "canning" operations. In that case, the disease would go away with the first hot weather. I don't think you need to worry about DM at all.

Once I deliberately brought home an infected plant. I stripped the bad leaves in the parking lot and sprayed the plant with copper after planting it. There was no recurrence.

You need to understand there was an outbreak of hysteria about DM in the rose community during the mid-90s. All sorts of crazy things were written and spread around.

Michael's right.

If this is only infecting stems and it is indeed a fungus, then it's not downy or powdery mildew, for both of those fungal species infect both stems and also leaves. Furthermore if you live in a semi-arid part of the country the chances that you are dealing with downy mildew are essentially zero. That fungus won't survive in your too-dry-for-it climate (on a rose growing out of doors).

jim1961 has a very good idea. Try and see if your county extension agent can give you any information (preferably of the "contact" sort) about how they get suspect plant diseases identified. I suspect sooner or later you'll be sending a sample to your state university (which I believe will be Washington State U., in Pullman).

Oh, one other thing. The easiest way to get a fungus identified quickly is to submit a sample of the fungus while it's sporulating (producing spores). If all you have is plant tissue infected with nondescript fungal tissue ("hyphae") that will be extremely difficult (ie., impossible for all practical purposes) for a pathologist to identify. If you see a white film in the autumn, my suspicion is that this fungus sporulates then.

Thanks! I am a little relieved, though still a bit confused-going from Powdery mildew to Downy and then just to a fungus!
I am sorry if I made a big deal out of the DM, I did not know just how unlikely it would be for a rose to get it here.

Fungus crops up because of damp conditions right? And it can infect a plant via cut/cracked stems? Does it spread from plant to plant, or just occur spontaneously?
Certain kinds of roses are prone to it, yes?
Can stressful conditions make the problem worse?

I read up a little about what should be done for fungus. Water just the ground to keep the stems and foliage dry, clean up all debris and trash it, cut away infected parts and trash them. Spray weekly with fungiside. Give soil good dressing of manure. Good plan??

Thank you all for your help. You have been wonderful.
(PS. does this mean I don't have to throw out all my roses?!! Yay!)
CMK

You fungal spots are apparently not any of the familiar, fairly serious stem cankers, so we don't know what it is. However, I've seen stuff like that in my garden and I don't worry about it. If the cane goes bad, I would just cut it off as I would a stem with botrytis canker or brown canker. Roses teem with various fungal problems in this climate. You have a relatively fungus-free climate-- relax and enjoy it.

Most fungal rose pests grow better in humid or damp conditions. Even powdery mildew (which often is simply more unsightly than truly destructive) usually grows better in climates with warm or hot, humid summers (although powdery mildew doesn't like out & out rain very much).

Fungi usually establish themselves more successfully via breaks of any kind in a plant's tissues. There are always a large variety of fungal spores in the air. When they land on the right part of a plant in the right weather conditions for that fungus, the landed spores will sprout and infect the plant tissue.