Nematodes........... reads like something from Jules Verne or John Wyndham, The day of the Nematodes ! I really think that the only good these critters do is line the pockets of the breeders of these so called voracious things. They last for a short time, cost a fortune to have any effect on a patch of allotment, and then one has to start all over again ! I have tried my own system, to broadcast slug pellets over a legume patch, rake it it well, and the molluscs go for it UNDERGROUND, leaving it safe for the birds, hedgehogs and wotnot that patrol of an evening. Better still, DIG the pellets in deeper than a raking !