Clematis wilt is one of the greatest misnomers in the care of Clematis. When you see symptoms such as sudden stem collapse with the stems and leaves turning brown or black in just a few days, you more then likely have a slug problem. Small, almost invisible slugs feeding on Clematis stems will cause symptoms similar to Clematis Wilt. A slug bait such as Sluggo placed around the plant starting in May will
prevent slug damage.