I planted my kohlrabi late but have left them in and they have carried on growing. From one angle I thought I had a lovely big one but from another angle it had all been chomped. They're under weighted membrane. Do you think rats or mice? Haven't had this problem before and I'm not very pleased!
Could be :voles; field mice; rats; rabbits;deer? Can you see the toothmarks? Judge for size, also any defaecation that may provide a clue. Footprints of the larger species?, any 'polished' trackways for the smaller. Personally, would unleash a (Little)Nipper or two, strictly for scienific purposes.