After reading To Till or not to Till thread, and several others,
I decided to remind folks. Sometimes you have to be a detective.
Do you have plants that just aren't growing, just stunted, looking unthrifty?
Are certain areas of your garden simply non-productive?
Why is that plant wilting so badly, when the others seem to have plenty of water?
You look the plant over, no noticeable bugs, no broken stems... what is the issue?
Sometimes, you have to dig for answers... come on, really dig.
Find one especially in trouble plant, and dig it up... remove the dirt from the roots, grab your magnifying glass and look at the roots.
Are they healthy looking? I have done this and found grubs galore on my roots, and other times, I find spindly little roots that just aren't growing, sometimes they are clumped and not spread out. But you might find galls, lumps and bumps, where nematodes have attacked the roots.
Not all nematodes are good guys... there are parasitic ones.
They are microscopic you can't see them, but you can see their destruction and the plants reaction to them.
I am including two pdf files one from Arkansas recommends winter tilling, to expose the parasites to cold and kill them..
The pdf from Arizona recommends soil solarization and taking the area out of production for awhile.
Both of these pdf's have merit, I think a combination of the two would work well. However, one says to remove all weeds... hey, check the weed roots too... if they are healthy, then they are not hosts and the parasites won't be fed by them, so they could continue there.
It goes on to say, planting plants that are not hosts is one way to use that area.
I would suggest, in really severe infections, solarize the soil for a couple weeks, plant crops that are resistant or simply not hosts to these parasites... like most parasites, remove the food and they die.
Then during winter, I would dig that area, and let the cold help kill these things off. Most of the parasitic nematodes are warm weather critters.
Please notice, it is not normally the entire garden, just zones of the garden!
This is contrary to Ruth Stout and many others, but this is organic parasite control. Ruth did not start with perfect soil, and neither will you, you must be a detective, you must do what you must do.
You won't totally eliminate parasitic nematodes, but with good organic practices, you will increase the good nematodes, and other biological helpers to keep them in check.