http://www.arbico-organics.com/categ...cial-nematodes this is a good company for treatment... they explain the different types on the site. I get some things from them and they are a good company, but I haven't tried the good nematodes.
I also read about using asparagus stalks to make a tea to drench the root zone of tomato plants.. thought I might try it just to see next spring... my sandy soil has concentrations where one plant will have horrible roots and the tomato next to it won't .. also I'm trying some of the university of Hawaii tomatoes that are nematodes resistant. Evidently Hawaii soil is full of them also.