Q: How can I kill a cottonwood tree that’s growing between my foundation and my AC unit? I drilled holes in the stump and poured rock salt and boiling water in the holes last spring. A few days later there was a new sprout on it. The stump is still as hard as the day I cut it.

A: Even though the trunk is hard, it’s dead. As long as you don’t see new green sprouts, the tree will remain dead. It will gradually decompose over the next year. You might see root sprouts come up a few feet from the foundation but they can be snapped off as they occur.