[Chocaholic]

Here’s what I got back from the extension center arborist:

Mike, my name is Joel Potter, I am a Regional Extension Agent and have been forwarded some pictures of your oak tree. I tried giving you a call, but did not get an answer. While I do believe a pathogen is at work on the tree, if you are not seeing other symptoms like a weak canopy or dieback in the canopy I wouldn't be too concerned. It looks like there is some wound response wood on the edges, which indicates to me that the tree is responding to whatever is going on there and likely has good vigor. My guess as to what is going on is that there was a wound on that side of the tree at some time in the past. Before the tree had sealed up the wound, a pathogen was likely introduced, which over time has caused the deformity. It could also be the result of some type of canker. Either way, the tree seems to be responding to it and without other symptoms it likely isn't a big concern. One thing I would be interested in would be looking for any signs of decay behind the deformity. I use a 2lb rubber mallet to sound on the trunk of the tree and listen for sound wood vs hollow sounding wood.

Let me know if you have any specific questions.

Joel Potter
Alabama Urban Regional Extension Agent