What poison for badly stressed pecan?

[Kneejerk Bombas]

I would be much more concerned about borers digging around in living cambium. If a borer that lives in dead wood were to show up, it would be of little or no concern to me. Shigo even went so far as to suggest that deadwood borers, like ants, were actually beneficial to the tree.
Randomly killing or repelling all insects is not smart. I see some of the big chain lawn care companies doing these blanket spray programs to attempt to kill every living creature other than plants. It means repeatedly dumping large quantities of mixed types of insecticides and fungicides over the entire property.
There are several factors homeowners fail to realize with this type of treatment, but most importantly is most insects and fungus are beneficial to the landscape.
Before you start an insect control program, know your target insect. Learn it's life cycle. Understand all the control options, so you can pick the one that is least likely to affect the non-target ecosystem, if you decide any control is needed.

Why would you want to repel all insects from a tree? Does the eucalyptus oil repel lady bugs? I bet it does.
When most adult borers lay it's eggs on deadwood, they hatch and the microscopic little borers soon die from lack of living tissue to feed on. It seems to me, if you wanted to protect the tree, you would put your concoction on the living parts of the tree and let the insects have their way with the dead parts. Not that I think randomly repealing all insects is ever a good idea.

 

[treeseer]

nothing random about targeted applications to wounds. why are you talking about drenching the whole yard?

 

[Kneejerk Bombas]

The target in my discussion is the insect, which as of yet is unidentified.
And you are right, we should hold off spraying the whole yard, at least until we identify a known threat, but I'll order up some DDT and sharpen the big chainsaws just in case.