I made a planter around a live oak tree with the soil up against the tree. Now I have termites in the tree. Should I have protected the tree trunk from the soil with something and if so what?

Hi! meow571, and Welcome to AMHD :)

I made a planter around a live oak tree with the soil up against the tree. Now I have termites in the tree. Should I have protected the tree trunk from the soil with something and if so what?Hopefully there is nothing wrong with your tree. Termites only eat dead wood, they don't eat the live wood from a tree.

When termites are found in or on a live tree, something is causing the pith or cambium layer of the tree to die. Termites invade and eat the dead cellulose. I have always used neem oil for termites in trees as it penetrates so well.

NeemFactSheet.pdf Cornell.edu (http://www.entomology.cornell.edu/Extension/Woodys/LandscapeHortPWT/Resources/NeemFactSheet.pdf )

I would suggest that you use neem oil as an insect growth regulator (IGR.) You will need to get it into every nook and cranny where those termites are. The use of a garden syringe can be very helpful in this type of application. You want to get your applications in direct contact with the termites and their larva as much as possible. Repeat applications as needed every 7-10 days.

Also:
Boric acid works on all such critters.
Here's a link to try: Boric Acid natural insecticide, Dry Rot treatment (http://alsnetbiz.com/homeimprovement/boric_acid.html)

Boric acid can act as an anti-feedent at 0.25% and contact kill at 0.6% or stronger. Diatomaceous earth could be used too.
Diatomaceous earth - Wikipedia (http://en.wikipedia.org/wiki/Diatomaceous_earth) Found at any swimming pool supply.

Termites Management Guidelines--UC IPM (http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7415.html)

K