Question
I have a majestic oak tree in my yard in Maryland.  Recently I have noticed a series of dark blotches climbing vertically on the trunk.  Upon examination, in the cracks where the dark blotches are it is moist.  Is my tree in danger?  Is there something I can do if it is? It would be tragic to lose this wonderful full canopied tree.

Answer
Bob:

Difficult to say the origin of these "blotches", but these areas may be a direct result of insect borers w/in the tree.  The areas that I am thinking of are dark brown to black, vertical,elliptical, and may be upwards of a foot from top to bottom.  Bark looks stained and appears to have had a liquid running out of the crack downward.  If this is the case, the best you can do is be sure it is being watered well (especially during hot/dry periods)and fertilized- all to keep the tree vigorous.  I wish there were a magic bullet, but unfortunately there isn't.  If it is borers, and the tree is growing good, there is a good chance that it may be around for a good many years to come.  There are some insecticides out there that can be applied to the roots, but they have some limitations.  Getting the insecticide to the insect is the big obstacle. If you wish, you can send a photo of one of these areas if you like and I will be happy to take a look at it.

Steve