Q: I had two dogwoods killed by termites. Do I need to treat the soil before planting new trees? 

A: Termites don’t eat the living part of the tree, they can only digest the parts that are already dead. So the termites did not kill the tree, something else did. My guess is that yours died of old age. You can plant another tree in this spot with no problems as long as you keep it healthy. There is no need to treat the soil.