Root maggots
Last year I started out with about 20 Sweet William plants that were left over from the years before. After last season I now have only about 4. Once they are dead, I pull them up and there are roots left. I found that this was caused by root maggots. Do you agree and how can I get rid of them?
Submitted by BHGPhotoContest

Sweet William is technically a biennial, growing vegetatively the first year and flowering the second. Most die after flowering, but a few tend to perennialize and come back. They can also self seed and continue to grow in the same area. I suspect that any worms or maggots you see in the soil where the roots were are simply there because they're feeding on the decaying roots, not that they caused the death of the plant.

Answered by BHGgardenEditors