Posted: 22/09/2013 at 10:26
The holes are probably made by keeled slugs which are impossible to eradicate unless you really poison the soil. Anti-slug nematodes ight work, but no experience of them.
The scabbiness is caused by having to much lime in the soil, If you are in a naturally lime area then nothing much you can do except add lots of organic material. Grow naturally resistant to scab tubers.
Getting a bit late for planting much now, maybe spring cabbages?