Hello,

Would it be possible to get a photo of the base of the tree, as well as an overall look at the tree?  I am curious if you are noticing any branches dying in the canopy, as well.

Thank you!

Ruth

Hello,

Thank you for the additional picture.  It is very helpful.

To start with, pruning sealer-the tar your neighbor spoke of- is typically not recommended, as it can impede healing of pruning cuts, and wounds.  (When accidental or unavoidable wounds happen on oaks, sealing can prevent infection with oak wilt so that is the time to seal.) 

What I suspect is happening with your tree is that it was planted incorrectly, and that this is starting to cause some stress and rot to begin.  The holes are from birds looking for insects that like the conditions in rotting wood.  I was looking to see the root flare of the tree, which is not visible at ground level, meaning that the tree's root system has been planted too deeply.  The best remedy for this is to get an arborist on site who can use an air spade to clear soil off the top of the root system without damaging it.  To get an ISA-certified arborist, go to treesaregood.org and find one in your area. The sod should be carefully removed around the base of the tree around its drip line, and soil excavated away until the root flare is visible.  Ideally, the grade should be corrected to prevent excess water from pooling on the roots and a shallow layer of mulch installed to keep the roots cool and moist.  Mulch should never be piled against the trunk. 

To read more about this issue:

Trees Planted Too Deeply | University of Maryland Extension (umd.edu)

I hope this is helpful!  Thank you for contacting Ask Extension.

Ruth