Thanks yes have tried this - the problem is that slug pressure is always so high in the rape (can't ever combine rape here at night as they will gum the grain pan in no time!) that the volunteers get eaten as soon as they germinate. That one area of volunteers is an anomaly. I though trying to drill a cover straight after the rape was worth a try but they decimated it too and I was reluctant to pellet at that stage.
Wow, and I thought I got a lot of slugs!