How do I save my large orange tree that appears to have termite damage at the base of the trunk?

Answer 1

Clear the soil away from around the base of the tree. Most termites, i.e. subterranean, need contact with the soil to survive. Try to keep the area near the base of the tree dry, applying water only well out under the drip line. If the termites contact with the soil is broken, they will not survive or do further damage to the tree.