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Hellebore Black Death

Posted by bruceNH z5NH (My Page) on
Thu, Feb 13, 03 at 11:31

Black Death is a virus many claim to be on the increase. It is virus that has no cure, once signs of the virus are apparent the hellebore die within 8 months.

I have heard reports that this virus is wide spread in the UK has moved into Mainland Europe, has been found in Australia, Canada and is present in the USA. It may be present were ever hellebores are grown in great numbers.

Will this be the hellebore demise? Or is this just myth, a virus spreading that kills hellebores with no known cure but to destroy any hellebore that looks infected?


Follow-Up Postings:

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RE: Hellebore Black Death

Belgium link with article and picture.

Here is a link that might be useful: Belgium Link


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RE: Hellebore Black Death 2

Belgium link second try!

Here is a link that might be useful: Black Death


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RE: Hellebore Black Death 3

Royal Horticutural Society, help and advice link.

Here is a link that might be useful: Black Death


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RE: Hellebore Black Death 4

Etiology Of A New Disease Of Helleborus Species In North America
Project Annual Reports
2002 Annual Report
Related National Programs
Plant Diseases (303)
Project Team
Mahaffee, Walter - Walt
Project at-a-glance
Project Number: 5358-22000-024-03
Project Type: Grant
Start Date: Sep 28, 2001
End Date: Jul 31, 2003
[Printer Friendly]
Objective:
Determine the relationship of carlaviruses to diseases of Hellebore in the PNW; compare the carlavirus with the viral disease observed on Helleborus in the eastern USA, and with "black death" disease reported in Europe/UK; determine whether other viruses or infectious agents are associated with the diverse range of symptoms observed on the infected plants; disseminate results and develop an IPM program.

Approach:
The carlavirus identified in Hellebore will be separated from other potential pathogens by transmission to alternative hosts. Aphid transmission will be used to transmit the carlavirus from infected plants of H. hybridus to healthy plants of Helleborus species. The inoculated plants will be observed for symptoms and tested for presence of carlavirus. This process will establish potential vectors of the carlavirus, and segregate the carlavirus from non-aphid transmitted pathogens that may elicit symptoms in nursery stock and, therefore, confound diagnosis of the disease. Once successful method of virus transmission has been developed, the host range of the carlavirus and any other infectious agents diagnosed in association with the symptoms will be determined. Plant tissues of Helleborus plants showing a range of symptoms will be examined for virus inclusions bodies using techniques developed by Christie and Edwardson (1986). The original symptomatic plants, sap-inoculated Helleborus plants, as well as Helleborus and indicator plants used in the aphid transmission



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RE: Hellebore Black Death

Opps! Meant to have another link, some how posted the whole thing! USDA link, click the "Summary With the Most Recent Annual Report".

Here is a link that might be useful: Black Death


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RE: Hellebore Black Death

Thanks Bruce, Thanks so much for the information. Today I was out there cutting off the old leaves of the plants and all I came across was the regular winter damage to the leaves. Some of my leaves got burned by the cold temerpatures we had this year but so far no black spotting. It looks really terrible. I have never seen aphids on my plants but will really look for them now.
Mary


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RE: Hellebore Black Death

interesting Belgian site!


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RE: Hellebore Black Death

  • Posted by MorZ8 Z8 Wa coast (My Page) on
    Fri, Feb 14, 03 at 0:02

Hi Bruce, Thank you. Let's hope this avoids my little corner of the world. I thought it was interesting that aphids may be suspect....the only insect damage I've had on hellebore was a heavy infestation of aphids on new shoots of foetidus Sienna last year; they'd really multiplied by the time I looked low enough in the evergreen foliage to notice.


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RE: Hellebore Black Death

Thanks Bruce. Ignorance may be bliss but Knowledge is power.
JoAnn


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RE: Hellebore Black Death

You should not confuse this virus with Conithyrium hellibori, black spot of hellebore. This fungus can be a huge problem too. It is described as large, irregular, dark brown to black spots on both sides of leaves often running together. This is very common on hellebore especially Helleborus niger.

You can also confuse this virus with Botrytis.

This makes the black death virus very confusing. From what I read and understand the virus will spread fast under different garden conditions than Conithyrium and Botrytis.
So the virus may appear when you would expect other leaf spots not to occur.

If you have alot of hellebore and have bought new hellebore routinely over the years from many different sources you should study and understand the different leaf spot fungus and this new virus.

If you have hellebore that have been around for a long time or have acquired from a friend who had the hellebore for a long time you should have little to worry about.

This virus has been identified just recently and has been established from what I have read in large horticultural businesses that grow hellebore.

I hope if any of the above statements are not accurate that it is corrected, if not in this forum send me an email. I consider private emails private and would not repeat the source of accurate information.

Bruce


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RE: Hellebore Black Death

Purchased a foetidus last year, my first. I have many nice clumps of helleborus, Lenten Rose, but no other varieties. The foetidus developed a black rot at the base of the plant which extended up the stalks. Tried to find what was killing it, have never had a problem with any fungus or any disease at all with the Lenten Rose. I dug it up eventually and destroyed it but the disease described here, does not exactly describe what I saw. Any ideas?


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RE: Hellebore Black Death

This sure sounds like the activity of one of the watermolds.
I have seen these symptoms myself in H foetidus, they are difficult to confuse with Coniothyrium (read Bruce's excellent discription above)and the end product is generally the death of the infected plant.

I routinely dip with one of the fungicides such as Fongarid or Alliette to prevent this.


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