Answer: If the damage includes roots, it may be caused by voles. These can be controlled by trapping. If the damage is only on the leaves, I would suspect slugs. These eat at night and leave silvery slime trails. These can be controlled by a variety of measures: trapping, baits (read and follow label instructions), hand picking, and also by sprinkling diatomaceous earth (a powder sold in garden centers) on the soil surface right around the plants.
Q&A Library Searching Tips