Ash with Emerald Ash Borer
I've diagnosed an ash in my yard as having emerald ash borer. It has about 50% die back and was never a favorite tree. I'm leaning towards cutting it down and putting in something else. Do I need to treat to kill the ash borer to prevent it spreading to neighboring ashes or will cutting down the tree be sufficient?
Your ash will not recover from that much damage and needs to be removed. The wood will be chipped by a tree service company to kill the emerald ash borer (it cannot survive in wood chips.) If you want to keep the wood to use as firewood, you should tarp it and let the EAB cook.
It is illegal to move infested wood out of county.