Fungus growing on our oak tree - Ask Extension
I have discovered a fungus growing about 1’ above the base of our oak tree. My question is, does this indicate the tree is diseased and needs possib...
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Fungus growing on our oak tree #814076
Asked October 12, 2022, 5:37 PM EDT
I have discovered a fungus growing about 1’ above the base of our oak tree. My question is, does this indicate the tree is diseased and needs possible removal?
I had a tree service do some weight distributive pruning so that, should it fall, it will likely miss an out building. This was done after its “mate” had fallen last winter.
Benton County Oregon
Expert Response
Thanks for contacting "Ask Extension" about your oak tree. Based on the pictures you sent I suspect the fungus is Pseudoinonotus dryadeus (formerly Polyporus dryadeus), a common root and butt rot fungus on oaks, especially Oregon white oak in western Washington and Oregon.
Below is a description of the fungus from OSU's PNW handbook, Let me know if the description doesn't match what you are seeing and we can do a further investigation.
The structure in the picture is referred to as a conk. These conks are normally large, (about 7 inches or more) and thick, tan to grey-brown on top with a pale-tan to grey underside (pore surface). The top surface of fresh conks has numerous droplets of clear-yellow liquid that darken with age. For this reason, it is sometimes referred to as the "weeping conk." The upper surface of conks weathers to black and deteriorates in winter to a dark-brown or black mass.
There is not much you can do to control the fungus once the tree has become infected. I recommend you have the tree inspected for soundness. Remove the tree if it has extensive decay to avoid damage to surrounding property.
I've included a link to an OSU publication with a little more information. https://pnwhandbooks.org/plantdisease/host-disease/oak-quercus-spp-inonotus-root-butt-rot
I hope this helps!
Below is a description of the fungus from OSU's PNW handbook, Let me know if the description doesn't match what you are seeing and we can do a further investigation.
The structure in the picture is referred to as a conk. These conks are normally large, (about 7 inches or more) and thick, tan to grey-brown on top with a pale-tan to grey underside (pore surface). The top surface of fresh conks has numerous droplets of clear-yellow liquid that darken with age. For this reason, it is sometimes referred to as the "weeping conk." The upper surface of conks weathers to black and deteriorates in winter to a dark-brown or black mass.
There is not much you can do to control the fungus once the tree has become infected. I recommend you have the tree inspected for soundness. Remove the tree if it has extensive decay to avoid damage to surrounding property.
I've included a link to an OSU publication with a little more information. https://pnwhandbooks.org/plantdisease/host-disease/oak-quercus-spp-inonotus-root-butt-rot
I hope this helps!
Dear Deb,
Thank you for your quick response to my inquiry. Yes, the description of the fungus/conk accurately describes what I observed, especially the clear liquid present at its early stages of growth. We will do as advised regarding assessment and recommendations.
Fred B
Sent from my iPad
Sent from my iPad
