Phytophthora ramorum - again

Discussion in 'Plants: In the News' started by Margot, Jul 4, 2019.

  1. Margot

    Margot Generous Contributor 10 Years

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    Please check out the news article found on the following link: Plant nursery faces major losses after pathogen found on shrub regarding finding phytophthora ramorum at Island View Nursery in Saanichton, BC.

    The following information can be found at: Phytophthora ramorum - Wikipedia

    Phytophthora ramorum is the oomycete plant pathogen known to cause the disease sudden oak death (SOD). The disease kills oak and other species of trees and has had devastating effects on the oak populations in California and Oregon, as well as being present in Europe. Symptoms include bleeding cankers on the tree's trunk and dieback of the foliage, in many cases eventually leading to the death of the tree.

    P. ramorum also infects a great number of other plant species, significantly woody ornamentals such as Rhododendron, Viburnum and Pieris, causing foliar symptoms known as ramorum dieback or ramorum blight. Such plants can act as a source of inoculum for new infections, with the pathogen-producing spores that can be transmitted by rainsplash and rainwater.

    P. ramorum was first reported in 1995, and the origins of the pathogen are still unclear, but most evidence suggests it was repeatedly introduced as an exotic species. Very few control mechanisms exist for the disease, and they rely upon early detection and proper disposal of infected plant material.

    Plant nursery faces major losses after pathogen found on shrub
     
  2. Ron B

    Ron B Paragon of Plants 10 Years

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    A world authority on the genus Phytophthora told me some years ago that the cat was out of the bag as far as P. ramorum was concerned - that it was already widely dispersed, making individual containment attempts such as the one described above pointless.
     
  3. Margot

    Margot Generous Contributor 10 Years

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    That doesn't come as a surprise when you consider how many plants shipped to BC from California are never even tested. The nursery that has been quarantined recently had no government inspections for a decade according to one of the owners. https://www.cbc.ca/news/canada/brit...antine-after-harmful-pathogen-found-1.5199332 Besides that, nurseries are only randomly selected for testing.

    P. ramorum has a broad host range, with hardwoods, conifers, shrubs, herbaceous plants and ferns, all known to be susceptible but it sounds like some plants that could harbour the pathogen aren't even on the list to be tested. I mean, P. ramorum is commonly called Sudden Oak Death - so are Quercus species not tested?

    Here is an item I found in HortWest_2008-09

    P. ramorum Directive Revised
    Directive D-01-01 “Phytosanitary Requirements to Prevent the Entry and Spread of Phytophthora ramorum” has been revised to reflect changes to the host list and to adjust the phytosanitary import requirements of plants imported from the United States in accordance with U.S. certification programs. The requirements for the import to Canada of plants under a Pest Free Place of Production certification program has also been amended.


    This change means that no longer are entire genera listed, except in the case of Camellia, Kalmia, Pieris, Rhododendron, and Viburnum spp. greatly reducing the number of recognized host plants, and alleviating some of the export-import complications associated with the directive.
     
  4. Ron B

    Ron B Paragon of Plants 10 Years

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    Tanoak acorn based traditional tribal economies in California has been disrupted by the extensive damage to the tree in its native area. Some groups have lost pretty much all of their source trees. This shows just how much of the pathogen is present there.
     

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