We call the foam "cuckoo-spit", our way.
Slugs are absolute little @#$%s when it comes to strawbs. If you're not growing organic, pellet regularly. If you are, good luck!! I noticed when the first strawbs I grew were planted in the ground these suffered heavily from slugging. The next three years plants, taken from runners, were grown in 6" pots and rarely got hit, even in the 2012 washout year. Now I have no strawbs in the ground, only in pots.
It's handy, too, as it makes my "beds" mobile. I can shift them from the south facing house wall in late spring to make way for the toms and cukes and shift them back again to a nice place to overwinter. Even force a few in the GH if I can find the room (hahaha).