damage on bird’s nest ferns
It looks to me as if there are multiple attacks going on. I have 3 bird's nest ferns, all in the backyard (light shade under tree ferns) in Sydney. They are several years old and it seems as if they have taken turns being the healthiest. The largest has leaves that are a good metre long, but something is eating the margins badly. I can't see any beetles, caterpillars, etc, but I know there are snails in the garden. The other two are smaller and one has lost most of its leaves (rot at the bottom?) and looks as if it is dying but it still puts out new leaves. Am I mulching them too heavily? I've allowed leaf litter to accumulate in the middle of each on the theory that it is what would happen in the wild and the back yard has been mulched, mostly with compost and leaf-fall. They are directly in the soil, which was damp in early spring, then dried out a lot. I haven't been paying much attention to the garden this spring - work, travel - but will do so now. Please advise: should I clean mulch and litter from in and around the ferns? Is the webby/dusty stuff in the 3rd image an identifiable infestation? Should I be treating the ferns with a pesticide or neem oil or putting out snail bait? Thank you very much for any advice you can give.
I can't seem to edit the post. Duplicate images and one missing, but I hope the message is clear.