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dave123
Member
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Posted: Wed Jun 25th, 2008 09:24 pm |
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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.
Attachment: disease1.JPG (Downloaded 11 times)
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Newt
Administrator
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Posted: Thu Jun 26th, 2008 06:33 am |
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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/detail.cfm?imgnum=5220087
http://www.forestryimages.org/browse/detail.cfm?imgnum=5220088
http://www.forestryimages.org/browse/detail.cfm?imgnum=5220089
Septoria leaf spot - click on pics for larger images.
http://www.forestryimages.org/browse/detail.cfm?imgnum=5259033
http://www.forestryimages.org/browse/detail.cfm?imgnum=5265034
http://www.forestryimages.org/browse/detail.cfm?imgnum=5259039
http://www.forestryimages.org/browse/detail.cfm?imgnum=5259041
Newt
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dave123
Member
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Posted: Thu Jun 26th, 2008 11:43 am |
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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.
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Newt
Administrator
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Posted: Thu Jun 26th, 2008 05:30 pm |
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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
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dave123
Member
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Posted: Thu Jun 26th, 2008 08:25 pm |
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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?
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Newt
Administrator
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Posted: Thu Jun 26th, 2008 10:13 pm |
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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
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dave123
Member
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Posted: Fri Jun 27th, 2008 02:13 am |
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Thanks again. I'll make a note to report back in the Fall to let you know how they are doing.
Take care
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Newt
Administrator
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Posted: Fri Jun 27th, 2008 04:42 pm |
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Dave, we'd love to know how they shrubs are doing in the fall.
Newt
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Current time is 09:41 am | |
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