I have a hickory tree that I am told is being attacked by hardwood borers. Woodpackers have been attacking the tree for the insects. The attacked areas that removed the outer bark & exposed areas are what alerted us to a problem. We saw this about a month ago. My question is: How vulnerable is the tree to falling? If it is subject to falling, how long might it take before it is weak & ready to fall? The tree is very old & probably 100' tall.
In general trees can be subject to many environmental and cultural stressors such as drought, poor drainage, too much moisture, temperature extremes, too much mulch, planting too deeply, soil compaction, etc. When stressed by the above conditions the tree will be more susceptible to insect and disease problems. Borers disrupt the vascular system and can cause dieback.
The best thing to do would be to find a certified arborist near you using the following website from the International Society of Arboriculture. http://www.isa-arbor.com/findanarborist/arboristsearch.aspx?
The arborists listed on this website have met specific training requirements and are best qualified to do an on-site evaluation of your tree. They can test for diseases, pests, is the tree a hazard, etc., and make recommendations if corrective pruning or removal is needed.
We question is about hickory trees NOT trees in general. I know I can call an arborist. I've had 3 arborists come & got 3 different answers. You haven't answered the question. Your canned response is of no help.
Here is a more direct answer.
We cannot tell you how weak your tree is without photos (which can be attached to these emails) but, even then, it would probably require an on-site visit, which we are not staffed to provide. That's why we recommend arborists. Arborists should be able to give you a more focused answer, but even in that case, there may be too many variables to provide you with an exact time when your tree will be liable to fall.
That said, there are certain rules of thumb that are used to decide when to remove a tree with problems. Read through the following fact sheet about the decision-making process for removing trees. It lists symptoms (dead branches, rot, etc.) that you may see in your tree and when those symptoms warrant removing a tree: http://extension.umd.edu/learn/how-do-you-decide-when-remove-tree
We hope this will be useful to you.