Mildew on Zepherine?

Sylvia Weiser WendelJanuary 21, 2014

Hi all,
I hope the picture is clear enough to see the white, powdery gunk on my Zepherine de Drouhin. Is this mildew -- in California, in a drought?
I had had it in a pot resting on a plastic saucer inside another pot. There was water in the bottom of the second pot. Could this have caused the problem?
Is this serious enough that I have to do something about it -- and if so, what?
Stumped, Sylvia

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Kippy(SoCal zone 10. Sunset Zone 24)

From what I have been told ZD is a mildew magnet in SoCal, sorry

    Bookmark   January 21, 2014 at 3:48PM
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Sylvia Weiser Wendel

Arrg! Remedies?

    Bookmark   January 21, 2014 at 3:50PM
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ingrid_vc so. CA zone 9

Perhaps a different rose? Think of this at 10 x 10 feet and covered with mildew to see the scope of the problem. I'm also seeing some mildew in my dry garden, but only in a few cases. When it's a recurring and tenacious problem that rose is gone.


    Bookmark   January 21, 2014 at 4:30PM
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Campanula UK Z8

Apart from using a fungicidal spray, Zepherine appreciates good not grown against a wall. Maintain a good pruning regime allowing plenty of air movement between the branches. It also resents dryness at the roots (I don't believe your saucer arrangement will be the problem).
For years, I had ZD against a north facing wall but when I allowed the canes to reach the top pf a supporting arbour and fall forwards, away from the confines of the wall, the line of mildew was apparent - all the leaves lower than the top of the wall were affected while the canes which were blown about in the wind were completely healthy.

    Bookmark   January 21, 2014 at 4:44PM
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Sylvia Weiser Wendel

I'd rather not use fungicides because I have dogs -- in addition to all the other reasons.
I'll move her away from the wall. Thanks for the tip, Campanula.
Zeph was a gift and she hasn't flowered for me once (since last August). Then again, she is still in an 8-inch pot -- would repotting help? I think she's ready for it.
For a while she was in a shadier location (but with afternoon sun) and I wonder if that could have started the problem.
Ingrid, thanks for pointing the way to a possible nightmare future.
All help is appreciated. Sylvia

    Bookmark   January 21, 2014 at 10:08PM
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Unlike rust and blackspot thrive in humidity, powdery mildew is actually one fungus that does better in dry conditions. It also prefers warm days with cool nights.


    Bookmark   January 21, 2014 at 10:33PM
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nikthegreek(9b/10a E of Athens, Greece)

If you don't have BS pressure where you live, hosing the plant down in the morning helps a lot with PM. Some people spray with alkaline compounds such as potassium bicarbonate or even just plain old horticultural summer oils which seems to help (the latter goes a long way towards controlling insect and acarea infestations also) but one needs to be careful not to induce other problems by excessive spraying. Sulphur also helps especially in its powder form but is unsightly.
(Please note: never use sulphur along with anything else, especially not in combination with oils, and wait at least 2-3 weeks before using another substance. Also both sulphur and oils should not be applied if max temps exceed 28C or are less than 7C and should not be applied in full sun. All these for fear of plant tissue damage)

As Camps said, full sun, good aeration and no water stress go a long way towards minimizing the problem. Many roses shake off their problem when they are mature and not stressed while in others it's minimised with the odd PM growth here and there which one can learn to live with. I have noticed that roses in pots tend to be more susceptible and this I attribute to pot induced stress (stress in their root system by being pot bound, water stressed or nutrient stressed).

Having said the above, some plants are just not suited to some places. PM does not like the same conditions as BS but thrives when the nights are humid (but not wet) and cool and the days dry and warmish, which makes it a problem in typical med spring and fall. If a rose is a real PM magnet and there is PM pressure where you live, only choices are meticulous (preventive) organic (in the chemical sense) fungicide spraying during the peak pressure seasons or the compost pile. Unfortunately many roses otherwise quite well suited to this kind of climate (eg. quite a few teas and chinas) are very mildew prone. Also bourbons and their close relatives are notorious for being PM prone.

This post was edited by nikthegreek on Wed, Jan 22, 14 at 0:41

    Bookmark   January 22, 2014 at 12:34AM
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kstrong(10 So Cal)

NOW! would be a good time to get rid of ZD if you don't want powdery mildew, do live in California and don't want to spray.

Just the facts. Time for a different rose.

    Bookmark   January 22, 2014 at 1:18AM
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I agree with kstrong - I tried to grow ZD for 5 years - in No Cal about 10 miles from the coast but one mile from SF Bay. Completely, absolutely 100% white from mildew all of the time. Even when I did spray it with fungicides, it didn't get much better. Was growing on a rose folly in the middle of a bed - it was by far the tallest thing there - lots of air & circulation. It is one of the only 2 roses I have shovel pruned in my gardening life -


    Bookmark   January 22, 2014 at 1:00PM
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kstrong(10 So Cal)

Also -- we should mention that ZD is a once flowering rose -- once per year, and only on wood that is already a year old. Who wants to take care of a rose in California that is prone to mildew and flowers only once. . . . .

Nobody I know.

Sounds like the "gift" was from someone who figured out they had made a mistake, and decided to pass that mistake on to you. If you can further "gift" it to someone outside California, then do so. Otherwise, I hear the compost pile calling "Sylvia -- over here."

    Bookmark   January 22, 2014 at 2:33PM
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nikthegreek(9b/10a E of Athens, Greece)

I thought Zephirin can produce more than one flush once established and mature as is typical of bourbons. Also not sure I understand this 'old wood' thing.

    Bookmark   January 22, 2014 at 4:06PM
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Sylvia Weiser Wendel

Wow -- what a cornucopia of helpful ideas.
Kstrong, I saw the neighbor's garden (he who gifted it to me) and he had a humungous ZD blooming against a west-facing fence. I may be a groundless optimist, but I'm not ready to get rid of ZD before she has ever bloomed. Of course, I may be eating these words in a year -- we'll see.
What I love about gardening is that it's so future-oriented. There's always hope.
Nikthegreek, I like your suggestions and I will try following them. We have the exactly wrong climate for mildew, obviously, and this warm winter with no rain isn't helping.

    Bookmark   January 22, 2014 at 9:43PM
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Yup, mildew can be forced by water stressing the plant, whether there is cool or damp or hot and very dry. So can rust be forced, even when conditions do not favor it. I never believed it until I did it. That's one way I can tell when I need to increase the water. As for ZD, she's obviously good some other places, but in over thirty years of growing roses in SoCal and haunting gardens all over the state, I've never seen her good anywhere. Mildew and rust are frequent issues and none have ever flowered as heavily as the famous rose porn shots J&P ran in their catalogs to foist her on their customers.

I've tried her a couple of times, in several different gardens. I even grew and offered ZD at Limberlost Roses, a specialty rose nursery I managed in Van Nuys, CA for a few years. In this area, a truly terrible rose. Kim

    Bookmark   January 23, 2014 at 1:03AM
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Campanula UK Z8

Zepherine will bloom more than once but.....the second flush are single blooms right at the end of the long summer growth.

I would agree that it is disheartening and upsetting, trying to nurture a plant which is unsuitable to the climate or conditions....and as yours is still potted, it might be best all round if you could gift this rose to someone in a more appropriate climate....because despite mildew issues, it is a glorious rose in full spring flush and its fragrance is memorable - someone will be thanking you, if you choose the recipient carefully.

    Bookmark   January 23, 2014 at 6:18AM
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So sorry for your Bourbon struggles! Zeph seems to thrive in Dallas, TX, and similar climates. The Antique Rose Emporium sells her but does not recommend shady locations and advocates regular water and good air circulation. The one I planted for my mom bloomed well in spring and fall (after it was established) and also threw out continuous blooms here and there during cooler (not dead summer) weather. It produced winter blooms! Maybe Josh in TX or some else in the region would like to swap a rose with you?

Mine in Portland, OR, gets some PM and blackspot and is about to move to a spot with better air circulation and one which suits my rearrangement scheme. Overall, she grows well and is mostly healthy in PDX in an organic (lazy gardener) garden. She has two flushes of bloom but has small continous flushes in between. In my garden, the spring flush is most dramatic.

There are some very fragrant pink tea roses and antique hybrid teas that grow best in non soggy (read non PDX), sunny climtates. Ingrid has some that make me sigh. Sigh.

Frustrated gardener sympathy--

This post was edited by PortlandMysteryRose on Thu, Jan 23, 14 at 15:46

    Bookmark   January 23, 2014 at 12:11PM
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It's probably worth noting that ARE states ZD is not suitable for shade, even though J&P stated in their catalogs (for how many decades?) it is "shade tolerant". Sort of reminds me of "William's" (the "customer service" person from the "New J&P") who promoted Mermaid as being "thornless" here on GW a few seasons back. Kim

    Bookmark   January 23, 2014 at 4:18PM
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toolbelt68 (7)(7)

Each year this is what some of our ZDs looks like. It does get black spot later on in the summer with a lot of the leaves dropping off but it keeps coming back year after year -- 15 or more so far. Must be the areas they are grown in. On the far side of the deck a couple are shaded by a dogwood tree and the house but we get a ton of roses.

    Bookmark   January 24, 2014 at 10:39AM
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nikthegreek(9b/10a E of Athens, Greece)


    Bookmark   January 24, 2014 at 11:25AM
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One of my (many) sisters used to live in New Jersey and she loved ZD there. It did very well for her. Roses are like real estate: location, location, location.

    Bookmark   January 25, 2014 at 11:39AM
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