Expert: Jim Hyland - 10/16/2009

Question
We have a live oak that has a trunk diameter of nearly four feet and off of the trunk are about four major limbs with the largest of these four being more than 2.5" feet in diameter.  One of the major limbs broke off and inside of the this limb was an open cavity probably about 10" in diameter.  This cavity was also home to wood ants.  The hole in the branch continues towards the main trunk.  My question is; can this or should this be sealed and how or should we cut into the remaining 3 feet of the branch in an attempt to expose the opening completely.  We will also be dealing with the potential of the tree's weight now being primarily on one side.  Thanks for your help....doug

Answer
A couple of things--If the limb was hollow and assuming it was up in the tree this means the tree is hollow up to at least this point on the trunk. And the other limbs at this point on the trunk will more than likely be hollow also. A tree can survive as a hollow tree but when the limbs are hollow these tend to break off. IF there is a structure that will be damaged if the limb falls then the tree maybe classifies as a hazard tree and could cause problems if the limbs fall hitting something.

IF there is a 3 foot stub left from the breakage it should be cut back to the trunk but not flush with the trunk--leave about 1/4 inch. There is not need to fill the hole it will not really help anything. Treat the hollow wound with an insecticide for ants this will stop these insects from living there. They are just taking advantage of the hollow as a home for their nest.

With out seeing the tree and examining the health it is difficult to give a definite answer. I would call the State Forestry Agency and ask one of their Forester to come take a look. OR hire a Certified Arborist to give you advice as far as the hazard part.
Here is a web link to the Association that Certified Arborist--do not call a tree service company they will only want to take the tree down to make money for them.
http://www.isa-arbor.com/findArborist/findarborist.aspx