Q. I ran across an item called Grub Guard in the catalog.
It contains beneficial nematodes. Would these be the same kind of nematodes
that attacked my tomatoes last year?
A. These are entirely different nematodes. These are good
guys and pose no problems to other plants. The ones that attacked your tomatoes
are probably root knot nematodes which are never good, always bad guys. You are
safe to use beneficial nematodes in your landscape.
Do these nematodes harm earthworms?
This particular product containing nematodes does not. There are products with similar names that do contain pesticides so make sure it is this product if you do not intend to use conventional pesticide. Other people may call it Milky Spore but Milky Spore are bacteria that aim at controlling grubs, not nematodes. You have a few options to choose from. Explore both as options or use both. Neither will harm earthworms.