6/22/2016 3:06 PM
Where are you located? The thresholds I've seen vary. The one you listed seems a little lower than what I've seen used as an indicator of serious damage. There are a few products out there that many have used with varying success. Avid and Nortica come to mind. There is a "new" product that is supposed to be labeled this summer and released shortly thereafter from Bayer. It will be called Idemnify. Research has shown it to have good activity on Root Knot. Nimitz from Quali-Pro has shown promise, but research has shown it isn't as consistent on rootknot as the others.
We typically manage through with minimal issues on the surface. Frequent foliar feedings (low rates) can help get you through periods of stress or times where granular fertility isn't cutting it. I would also advise looking at your disease pressures as there seems to be a high correlation with nematode damage and other root pathogens.
Also, try to run counts in the spring and fall depending on your location. Here in the heat of the summer counts will be lowered as they move deeper in the soil profile. Also, keep in mind the counts can vary quite a bit depending on if you hit a pocket of high or low concentration. For example, I took two counts from one green following protocol and the numbers were way off from each other. Nematodes aren't typically evenly distributed evenly throughout a green. Good luck!