The chunks sounds like cutworms. The Sevin dust should help with them. The small holes is most likely slugs. You'll need to use Sluggo or something similar for the slugs. Sevin won't have any affect on them. Some people use an ammonia spray to kill the slugs, a ten to one mixture (ten parts water, one part straight ammonia) and go out in the evening or early morning and spray the slugs directly.
