Well Bobad, it's reassuring to know that I'm not the only one who's heard of the copper effect.

The other unproven (by me) method for slug control was "get a goose." I have seen several articles claiming that geese like slugs and will gobble them up. Unfortunately I've also seen a similar number of articles that say geese are good at keeping the weeds clipped (like rabbits, but it takes fewer of them); and I can't say that anything green would necessary be safe in the path of a herd of marauding goosees.

John