Identification: Is this something other than powdery mildew?

Discussion in 'HortForum' started by meddy, Jan 21, 2015.

  1. meddy

    meddy New Member

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    Nelson, New Zealand
    Hi everyone,

    I have some Chardonnay and Pinot Noir grapes growing at home that I hope to make wine with someday. I was hoping for my first vintage this year, however I have an unknown fungus.

    Last year I recognized they had powdery mildew so I sprayed them over winter and in the growing season since. The foliage is very healthy and there is very little powdery mildew, however the grapes themselves have a combination of a grey powder and black/purple covering on the skin. This black/purple covering can be scraped off. Some of the berries are splitting already and we have another 2 months to go before harvest here in NZ.

    Photos are attached.

    I would have thought this was severe powdery mildew but the leaves are OK? Any feedback/help would be greatly appreciated.

    Thanks in advance!
     

    Attached Files:

  2. Ron B

    Ron B Paragon of Plants 10 Years

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    If you have an agricultural agency there with a public outreach program try them. As the grape is an agricultural crop they probably know all about what you have going on.
     
  3. Ludwig Ammer

    Ludwig Ammer Member

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    This is Botrytis cinerea. We use this mold fungus in central Europe for Frost Wines we name "Eis-Wein". Although you have 4 times more gluconic acid and much more glycerine then normally in these Ice-Wines, people pay much more money for that toxic waste (in my mind).
     
  4. vitog

    vitog Rising Contributor 10 Years

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    This looks nothing like the Botrytis that I see every year on my hybrid grapes. Botrytis affects the whole berry deeply, causing it to shrivel. The disease shown can be scraped off the surface of the skin, which is not the case with Botrytis. It looks a lot like Powdery Mildew, but I'm not sure about that diagnosis.
     
  5. Ludwig Ammer

    Ludwig Ammer Member

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