Q: Writing in your recent email newsletter about dogwood twig borer, you told the questioner that grass growing under a dogwood can have a detrimental effect on the tree. We have vinca vine growing under our 30-year-old dogwood. The tree is beginning to have dead branches and I was wondering if the vinca could be causing the dogwood’s decline.

A: Vinca is not nearly as deleterious as turfgrass. It’s roots are relatively shallow and so do not steal nutrients and moisture from a tree like lawn grass does. In my experience, dogwoods live about twenty-five years in Atlanta; any enjoyment you get beyond that is borrowed time.