The tree looks like it was stressed and is trying to come back at the base. This is probably not the work of the borers, which are taking advantage of the dying trunk. I can't tell what made those holes, but EAB doesn't attack Mountain Ash, only the true ash trees in the genus Fraxinus and some closely related trees.
Good thought to not transport any borers if you cut the tree. You can burn the wood, or chip it to less than 1/2" on 2 sides, and it will be too small for most pests to survive.

Tom Valente
Aug. 14, 2023, 1:35 a.m.