Question
i have a pin oak about 30-40 yrs old in my front yard! I had a yard sale and nailed some nails into it about 2 yrs ago, i noticed it started to rot about 10 ft from the ground all the way to the ground so my neighbor said, "to stop that tree from deying put some roofing tar on it" well i did about a yr ago and i thought it was working but it didnt! It still has a lot of soginess and bugs!!  so i cleened it all out(like 3-4" deep now!  whta do i do now to save it?

Answer
Stephen:
Unfortunately, there is no magic bullet for this situation.  The internal decay is a slow yet progressive condition.  Usually microorganisms (bacteria and/or fungi) enter through a wound in the bark.  There may be a progression of different organisms, then insects move in after the fact and use the decayed area for a home away from home. Roofing tar, concrete, or pruning paints do not fix the problem, in fact they may harm more than help.

The key to these type of tree diseases is prevention. Preventing wounds from lawnmowers and string trimmers can be a big help. Good pruning practices along with proper watering and fertilization can promote vigor.

Eventhough there is some apparant decay within the tree, proper fertilization and irrigations may help prolong the live of the tree for years to come.  However, at some point, maybe years from now, the tree will start to develop dead branches in the canopy and may succumb.  The decay will weaken the tree structurally.  Often times we don't see this until there is an ice or wind storm that causes the weakened tree to break over.  This could be a problem for your next door neighbors Escalade or buildings. So, watch your tree every spring to see how well it leafs out and how well it fills out.  At some point you may have to decide to make firewood out of it to prevent damage to person or property.

Regards
Steve