This is part of the issue with the invasive Golden Oyster in North America, their mycelium paralyze and kill nematodes very efficiently which (directly or indirectly) leads to outcompetition of native fungii. https://news.ycombinator.com/item?id=47536102

They're commonly foraged, and naturally present a curious question of whether they're a vegan food since they're carnivorous.

It's an interesting idea, the biggest issue is that the BLD pathogen lives in leaf tissue and most nematophagous fungi dwell in soil or woody stems. If an endophytic fungi were found to have an adverse effect on nematodes, that might be the key to making this work. See 'phyllosphere microbiome' research for real attempts at doing this sort of thing.