oak tree ?disease? - Ask Extension
This is on a small, approx 8" oak tree in my front yard. The leaves were turning yellow in the middle but not top and bottom so I looked closer....
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oak tree ?disease? #889133
Asked October 31, 2024, 5:07 PM EDT
This is on a small, approx 8" oak tree in my front yard. The leaves were turning yellow in the middle but not top and bottom so I looked closer.Pics taken today, Thur. 10-31-24 Can you tell me what this is?? I will send 3 e-mails as the pictures are too large, from making a pdf, don't know why. I ha more pictures if you would like them.
Oakland County Michigan
Expert Response
Hi John,
Bur oak does develop corky ridges on the twigs, so this may be normal development? The webpage at the link below has some images (if you click to view all of them) of the corky bark on the twigs.
https://ohiodnr.gov/discover-and-learn/plants-trees/broad-leaf-trees/bur-oak-quercus-macrocarpa
The leaves turning yellow in the middle of the tree could be caused by chlorosis. I notice that the leaves are yellowed, and still green around the veins; that is classic chlorosis. Could be genetics in the tree that caused just those leaves to show symptoms, or it could be that you are just catching this early.
Because chlorosis is caused by at high pH of the soil, first step is to test the soil pH. You can do this through your local MSU Extension office for a cost of $26 (includes shipping) or you can purchase a simple soil pH test kit from your local garden store. Ideal pH for a bur oak is 5.3 - 7.4.
When the soil pH is over 7.4, macronutrients like manganese and iron are locked up in the soil, and the tree is not able to absorb these for use in the photosynthetic process and the chlorophyll (that gives leaves their green color) begins to break down. It is possible to amend the soil, or provide those macronutrients to the tree via supplement.
The bulletin at the link below explains chlorosis, and how to treat it.
https://edustore.purdue.edu/item.asp?Item_Number=BP-27-W
Happy to answer any questions along the way.
Thank you,
-Julie
Bur oak does develop corky ridges on the twigs, so this may be normal development? The webpage at the link below has some images (if you click to view all of them) of the corky bark on the twigs.
https://ohiodnr.gov/discover-and-learn/plants-trees/broad-leaf-trees/bur-oak-quercus-macrocarpa
The leaves turning yellow in the middle of the tree could be caused by chlorosis. I notice that the leaves are yellowed, and still green around the veins; that is classic chlorosis. Could be genetics in the tree that caused just those leaves to show symptoms, or it could be that you are just catching this early.
Because chlorosis is caused by at high pH of the soil, first step is to test the soil pH. You can do this through your local MSU Extension office for a cost of $26 (includes shipping) or you can purchase a simple soil pH test kit from your local garden store. Ideal pH for a bur oak is 5.3 - 7.4.
When the soil pH is over 7.4, macronutrients like manganese and iron are locked up in the soil, and the tree is not able to absorb these for use in the photosynthetic process and the chlorophyll (that gives leaves their green color) begins to break down. It is possible to amend the soil, or provide those macronutrients to the tree via supplement.
The bulletin at the link below explains chlorosis, and how to treat it.
https://edustore.purdue.edu/item.asp?Item_Number=BP-27-W
Happy to answer any questions along the way.
Thank you,
-Julie
