With the coriander plants... try sprinkling some snail pellets around as the slater bugs eat everything.. or try a yoghurt container buried at ground level with a watery yoghurt slush in it. The slaters crawl into it to taste the yoghurt and drown.. Hopefully... Beware the pets though they like to drink it.. it wont hurt them just wont get rid of the slaters either... perhaps a rock or log over the top to stop the pets if you have any.. Good luck I'm in W.A too and those slaters eat everything new and young in the garden!!