I have a Zoysia lawn that has been diagnosed with "Ring" Nematodes (Criconemella) by the U of A division of Agriclture labs. From the fact sheet that they have included, I have gathered that for the most part, about all that can be done is to practice proper cultural practices. Aeration is another suggestion (which I will do and then it also said that there may be some organic products out there that might work however no specific products were really offered due to ongoing testing. Chemical control is not an option due to toxicity to the environment. I'd like to know if anyone has had any success with any particular organic product or could give some suggestions on control.