The stump does not have to be ground out, but stumps with bark intact from infested tree removal may not extend more than three inches above the ground. If the stump is taller than three inches, the stump must be completely debarked. Emerald ash borer reproduces beneath the bark of ash wood. Leaving bark intact wood or stumps on a property allows emerald ash borer to reproduce and go on to infest other nearby health ash trees. If the stump is in a high traffic or grassy (mowed) area, you may want to consider removing it for aesthetic or safety reasons, but it is not necessary for disease/insect control.