slugs &potato's

we seem to be getting an increase in slug damage quite noticeable when digging the crop at the end of the season maybe we could be leaving the crop  to long in the ground before lifting  I've found this slug problem to be  on both plots we plant although rotating each potato plot  per season


I was thinking about putting slug pellets on the potato ground to control the slugs but I'm not sure when is the best time to put slug pellets on potato ground when platting or on top of the ground before ridging up the crop 

Some varieties get more slug damage than others, so changing variety helps.

Many of the slugs that cause potato damage are underground slugs, so putting slug pellets on the surface would have only limited effect.  I have heard of people putting them in the ground at planting time (or earthing up?), but don't know how effective this would actually be as I assume the pellet would disintegrate quite quickly.