Posted: 06/03/2015 at 18:54
It looks like keeled slug damage (and I know that well, unfortunately!) I often find other creatures then get in via the holes. I also use nematodes but keeled slugs still remain in my soil, although damage is reduced. These varieties are resistant to keeled slugs in my experience: Kestrel (2nd early and v.tasty), Pink Fir Apple (maincrop) and Sarpo Mira (maincrop), so suggest growing those to your client.