Shiro and Methley Plums Black Knot

Discussion in 'Fruit and Nut Trees' started by CherylZ, Jun 4, 2015.

  1. CherylZ

    CherylZ New Member

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    Location:
    Maple Ridge
    Both my shiro and methley plum trees are infected with black knot. We tried to prune out the infected branches as we saw them in the winter but a few months have passed and the problem seems to be spreading very rapidly. The trees are bearing lots of fruit so we'd like to wait until after harvest do remove them.

    After that point, I wonder if it would be safe to plant new fruit trees in the same location? From what I understand, the fungus spores can infect other stone fruit trees as well. Any advice would be greatly appreciated! I really want to grow some fruit in our yard but I worry about this fungus infecting anything we plant now.

    Thanks for your input!
     
  2. vitog

    vitog Contributor 10 Years

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    Location:
    Burnaby, Canada
    It's best to remove infected branches as early as possible. I have a multi-variety plum that occasionally has branches with black knot. I just remove them as soon as I notice them, and the black knot has not become a serious problem. Perhaps Shiro and Methley are more susceptible, although on my tree the European prune plum seems most susceptible to black knot. I don't recall ever seeing it on the Japanese plums.
     
  3. Richard Hallman

    Richard Hallman Member

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    Location:
    Langley, BC, Canada
    Hi to all,
    The critical time for Black Knot infection is from bud break in the ealry spring through blossom time. All cankers should be cut from the trees and removed from the garden or orchard (destroyed if possible) prior to this time. I agree with vitog that the cankers should be removed when you see them, finding them a second time is challenging. Remember to remove at least 4" - 6" beyond the canker to ensure you are removing the entire infection. One reason to remove them as soon as you see them in spring or early summer is the fungus has not had enough time to infect the branch much beyond the canker making it easier to remove the entire infection. Although I must admit, at this time of the year I usually wait till the fruit ripen before removing the cankers.

    The best information that I am aware of about susceptibility is as follows: Stanley, Damson, Bluefree and Shopshire are very susceptible; Fellenburg, Methley, Milton, Early Italian and Bradsaw are moderately susceptible; Formosa, Shiro and Santa Rosa are slightly susceptible; and President is highly resistant.

    I hope this helps.
     

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