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Do my roses have Verticillum Wilt?

Posted by melissa_thefarm NItaly (My Page) on
Sat, Oct 13, 07 at 2:23

In the last couple of years I have had a number of roses that, apparently healthy, have suddenly had a cane wilt, turn brown, then die completely. In some cases the plant died, in others the plant survived. I put out a thread about this but didn't receive any plausible answers as to the problem. I recently heard about Verticillum Wilt and it sounds as though it may be the culprit. Can any of you experts tell me about it? What does one do about it? Are there organic solutions to the problem? Where I lost roses this way I didn't replant with roses.

As a non-rose addendum, do oaks get the disease? I've seen oaks on our property that showed similar sudden dieback.

Thanks for the help!

Melissa


Follow-Up Postings:

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RE: Do my roses have Verticillum Wilt?

  • Posted by bboy z8 WA USA (My Page) on
    Sat, Oct 13, 07 at 3:44

If there is a government agricultural agency there that can provide testing and diagnosis (here we have the USDA Cooperative Extension Service) that would probably be your best source of assistance.


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RE: Do my roses have Verticillum Wilt?

The enclosed link from Oregon State University is the single best reference to verticillium wilt in roses that I could find. Evidently, resting forms of the fungus can survive in the soil for years and revive to attack the roots of roses - and oak trees. There is no cure short of fumigating the soil but some rootstock varieties are more resistant than others. The rootstock, 'Manetti', is supposed to have a high degree of resistance. In the US, Manetti was once the favored rose rootstock of Wayside Gardens. I don't know if it is available in other countries. At any rate, bboy's advice of soil testing and diagnosis seems like the best place to start.

Here is a link that might be useful: OSU Link


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RE: Do my roses have Verticillum Wilt?

I agree that you need professional diagnosis. If oaks are dying in your area, university scientists and government ag agencies probably know the cause.

There is another fungal disease in California that attacks both roses and oaks fatally through the roots.

Verticillium usually is not fatal to roses but kills an occasional cane or two. It can be treated with a soluble copper soil drench applied annually. A product called Phyton 27 is labelled for this use in the US. I have heard of copper sulfate being used. However, you need precise instructions, because concentrated copper is toxic to plants as well as soil life.

I have a belief that rose plants can develop resistance to verticillium after prolonged exposure.

Leaves on affected canes die from the bottom up with large areas of yellowing on the leaflets. Shoot tips wilt. Roses with verticillium do not present the brown ring in the inner bark that is disgnostic on some other plants.


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RE: Do my roses have Verticillum Wilt?

I remember reading a study that provided evidence that application of potassium as fertilizer is therapeutic to maples that have contracted verticillium wilt, allowing them to slowly recover. I've used it myself for roses I suspected of having the disease, and haven't lost any, but I'm afraid that isn't any sort of proof. I don't have the reference handy - but I found it online, so it may still be available.

Stefan


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RE: Verticillum Wilt?

I read a recent study with a new finding that many plants use elemental sulfur to combat systemic fungus diseases. They have a mechanism to reduce sulfate taken up by the roots and produce S to line the plumbing system. Roses weren't mentioned.

Sulfur is supplied by organic matter, gypsum, epsom salt, ammonium sulfate, etc.


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I may have one lousy picture of Verticillum Wilt

FWIW, I had some potted roses that were probably infected with verticillium wilt. The dieback and death was sudden and dramatic. I may have a picture somewhere, not great because I don't have the high resolution image with me. The dieback canes turn black and look very distinctly black and poisoned. Leafdrop is sudden and dramatic. Canes die to nodes, showing the vascular nature of the disorder caused by the fungal pathogen or the plant's response to it. In essence, the fungus invades the water transport system within the plant, and the plant responds by blocking that system to stopgap the spread of the fungus. Since the fungus enter through the root system, the plant will not win.

In the linked image, the cane in front of my palm shows the discoloration of the bark. The cane to the right fork is green. To the left, it is black and dead. Below, the cane is mottled and obviously infected. Sorry the shot is so bad. You can see massive leaf drop. The plant arrived beautiful and fully leafed out. Within a few days, the canes started turning black and dying.

Here is a link that might be useful: Fork of canes showing VW


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RE: Do my roses have Verticillum Wilt?

*** I, too, lost some plants this summer to what may very well have been VW.

> CASS SAID: Since the fungus enter through the root system, the plant will not win.

*** Boy, is that ever true. Only one victim survived.
That one was a large mature plant, which was in the ground. One cane remains, of what must have been at least 8 big canes.

Jeri


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RE: Do my roses have Verticillum Wilt?

Excellent photo, Cass. It reassures me that VW was not what was bothering my Sombreuil. I had read about VW at the time and wondered.
Thanks.
Sherry


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RE: Do my roses have Verticillum Wilt?

But did Cass or Jeri get a professional diagnosis? I didn't either :)

I'm not sure rapid blackening and death are recognized symptoms of VW. As I read the descriptions, the death of leaves is fairly gradual, progressing up the cane, and the cane dries out fairly gradually, wilting and shrivelling first at the top.

Years ago, I got a (for me) big order from Pickering. It was the year they reported crop failures for a number of varieties (attributed to flooding), and shortly before they moved to the new farm. Two of these plants showed wilt and dieback symptoms that I had never seen. The soil was freshly mixed and uniform over a bed with about twelve new plants. The symptoms matched descriptions of VW very closely. I didn't get a diagnosis because, from what I learned, it wasn't treatable by anything I was willing to do, and the soil was now contaminated, so I left the plants alone. They lost about a third of their canes the first two years, then maybe one or two the third year, and have been free of symptoms and nicely productive for maybe five years.

From the Horst Compendium of Rose Diseases:
"initial symptoms... wilting leaves at the tips of young canes and a yellowing of lower leaves. After a few days, permanent wilting occurs... Defoliation progresses from the base of canes upward. Canes that show symptoms may continue to grow normally in subsequent seasons, or they may die back. Dieback begins at the tip and progresses downward, and... purple-black streaks frequently occur... along the shoot... can result in death of entire plants.

"Symptoms appear during periods of stress, such as drought.... Symptoms on outdoor-grown roses are usually less severe.... Field grown roses recover naturally, and infection periods are limited primarily to winter and spring."

Color plates of infected stems show green stems with dark streaks, yellow stems, and brown stems, and leaves that are mostly bright yellow with some green.


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RE: Do my roses have Verticillum Wilt?

I want to second Cass' experience. I lost close to half of my rooted-potted roses a years ago that based on the description both Cass and Paul Z. diagnosed as verticulium wilt. I was so upset and frightened seeing the quick spread of this sudden death that I discarded all plants along with the soil in plastic bags that could have caused it. Paul advised me to get industrial strength Hydrogen peroxide and spray the plants and soil with that. I got it (not cheap for a home gardenere) but the disease was so advnaced that the treatement didn't save those plants; maybe it save a remaing few to catch it.

As to Jeri's experience, Paul also said that bigger plants or plants already in 3- gallons would probably survive. My plants, however, were all 1-gallon well developed seedlings.

After the fact it occurred to me that I should have sent a few to Raleigh for testing - staircase wit, what can I say.


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RE: Do my roses have Verticillum Wilt?

No, I did not get it diagnosed. I know, I know. I should have. But at least I'm not alone. I really think I was in denial, and I still have problems discussing it.

At least the problem was confined to the house level of the garden. Nothing on the hillside was affected, and nothing up at street level, either.

I lost 2 plants that were well-developed 5-Gals., btw.

Jeri


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RE: Do my roses have Verticillum Wilt?

I didn't feel the need to consult a professional under the circumstances. The nursery that sent the plants was familiar with the problem. It's a recognized problem in that region.

How many things can do that to a big, healthy vigorously growing rose? The decline of the plant is completely different from a water-stressed plant. It was a total collapse with canes turning black.

I'm interested in suggestions of alternative causes.


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RE: Do my roses have Verticillum Wilt?

Just sayin' that total collapse with the canes turning black isn't the standard description. I've no idea what it was, but there are various fungal root rots and a phytopthera wilt disease. Did your disease come from an own-root nursery?


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Rats! Too many brain cells squandered

Michael, you're absolutely right. I'm glad you persisted in face of my certitude. I can't remember now if it wasn't fire blight, doggone it. Grrr. An aging memory is a terrible thing...


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RE: Do my roses have Verticillum Wilt?

It wasn't phytophthera.
We know phytophthera here -- this is the phytophthera capital of the world.
This was something else. And at a different time of the year.

Jeri


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RE: Do my roses have Verticillum Wilt?

You'll want to maintain hydration and try to use a water soluble fertilizer high in potassium while avoiding water soluble fertilizers high in nitrogen.

Potassium will enhance fluid transport within the rose's vascular system while nitrogen would promote growth placing more strain on the plant.

It is not a cure but may work in some instances.

In the end, it's remarkably similar to what we do for hypovolemic patients in the emergency room, albeit by different means.

HTH,

MichaelAT


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RE: Do my roses have Verticillum Wilt?

It may not make you folks feel better, but it's a comfort to me, at least, to know that other gardeners, GOOD gardeners, suffer from these problems as well. I'm in good company at any rate.

The discussion was long on ideas and a bit short on prescriptions, at least for a gardener who was looking for a pill. We did have an expert from the Forest Service come out for our oaks, but he, and his diagnosis, were a bad joke. This is Italy, folks. He certainly left us wondering if he didn't cheat on his college exams (there was a big scandal about this recently in southern Italy). I think my next step is to go to the Italian gardening forum I frequent and ask where one gets a diagnosis for this kind of problem, because I do need to know. In the meantime I think I shall continue to prune away diseased growth and watch to see what happens.

I appreciate the input and suggestions, will be re-reading and studying them. It probably matters that we are in our second year of drought and it is still very, very dry--we've had roughly five inches of rain since the start of July--so the plants are under stress for that. Our water supplies are limited, so we only water recently planted roses and true emergency cases.

I suppose I can count myself lucky that out of three hundred roses there are only three or four that I know are sick. We had a lot of dieback during the summer but I think most of it was drought stress. Even with the drought, now that the weather's cooler the roses are leafing out timidly and replacing the growth they lost during the summer. Of course, new cases may show themselves.

Thanks again to everyone. In a strange way it's reassuring to know that even when an ugly disease strikes gardening goes on all the same.

Melissa


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RE: Do my roses have Verticillum Wilt?

Melissa,

I don't know the governmental orginisation in Italy, but maybe the Forest Service is not the organisation you should contact about plant diseases. Every European country should have a National Plant Protection Organisation. In the Netherlands we have one that is seperate from the Forest Service, maybe in Italy this is also organised seperately. I tried to find more on the internet, but the only thing I found was that it resides under the Department of Agriculture (Politiche Agricole). Maybe you can find more on their website?

BTW, it would be interesting to compare Jeri's observations on the symptoms of Phytophthora ramorum to what you are seeing. This also affects oaks and kills them, apparently, because the name in the US is Sudden Oak Death. However symptoms appear less severe in European countries where this (rarely) occurs, mostly on beech trees and rhododendrons. It is a good thing to rule out as the cause, though.

Rob


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