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  1. #1
    Hi. I just bought several redtwig dogwood shrubs (cornus baileyi) that are in pots, and for the most part look very healthy. But scattered about them are some leaves that are either yellow, or have some holes in them, or both. A pic of a particularly bad leaf is attached.

    I see no insects or scale or anything odd on the leaves otherwise.* I suppose the yellowing and the holes could be due to different causes?

    Just curious if I should be intervening on this. Am in western PA. Thanks for any help.

  2. #2
    Join Date
    Sep 2003
    Location
    Maryland zone 7
    Posts
    3,042
    Hi Dave,

    I'm thinking either Cercospora or Septoria Leaf Spots.* Take a look here at the descriptions of these and other diseases to see what might fit.
    http://hgic.clemson.edu/factsheets/hgic2003.htm

    Cercospora leaf spot images - click on pics for larger images.
    http://www.forestryimages.org/browse...imgnum=5220087
    http://www.forestryimages.org/browse...imgnum=5220088
    http://www.forestryimages.org/browse...imgnum=5220089

    Septoria leaf spot - click on pics for larger images.
    http://www.forestryimages.org/browse...imgnum=5259033
    http://www.forestryimages.org/browse...imgnum=5265034
    http://www.forestryimages.org/browse...imgnum=5259039
    http://www.forestryimages.org/browse...imgnum=5259041

    Newt

  3. #3
    Hi Newt. Thanks, some of those photos do look very close. I hadn't realized dogwoods as a group were so disease-prone. There are several dogwood trees here that have grown beautifully despite widespread neglect, and certainly no pest-monitoring. But maybe I shouldn't have bought so many shrubs.

    There are some leaves though that are just yellow, with no spotting or holes, and I assume they are not part of this problem.

    Thanks again.

  4. #4
    Join Date
    Sep 2003
    Location
    Maryland zone 7
    Posts
    3,042
    Dave, you are very welcome!* Our native dogwoods are having their problems, especially with anthracnose, but they are still valuable plants in the landscape, especially for the wildlife value.* I don't know how many you purchased, but diversity of plant material in the landscape is always best.

    I suspect that your problems are from crowded conditions in the nursery, and with diligence cleaning up diseases and/or fallen leaves, you can easily get this under control.* There are some environmentally friendly remedies you can have at your fingertips.* For a fungal problem I would suggest the vinegar fungicide recipe.* If you see no improvement try the baking soda recipe.
    http://www.ghorganics.com/page15.html

    For insect pests you can make these as natural pest controls.
    http://www.ghorganics.com/page9.html

    There are some leaves though that are just yellow, with no spotting or holes, and I assume they are not part of this problem.
    I'm thinking you are correct.* Some things that can cause yellowing of leaves would be (I suspect the first in your case):
    rootbound plant
    overwatering
    natural aging and shedding of leaf
    mineral deficiency

    Do let us know how your plants are doing and if you need sites on how to plant, mulch and water.

    Newt


  5. #5
    Hi again. I will try the vinegar spray first. But also, I assume that any leaf that shows spotting or holes should be pniched off and discarded elsewhere?

  6. #6
    Join Date
    Sep 2003
    Location
    Maryland zone 7
    Posts
    3,042
    I will try the vinegar spray first.
    Great!

    I assume that any leaf that shows spotting or holes should be pniched off and discarded elsewhere?
    Yes, and "elsewhere" should be the trash and not the compost heap.* Sorry I didn't make that clear.* :?*

    Newt

  7. #7
    Thanks again. I'll make a note to report back in the Fall to let you know how they are doing.

    Take care

  8. #8
    Join Date
    Sep 2003
    Location
    Maryland zone 7
    Posts
    3,042
    Dave, we'd love to know how they shrubs are doing in the fall.

    Newt

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