I found my melons infested by these this year, and apparently there’s no practical control for them in a home-sized garden, other than taking it out of production/solarizing.
A number of vegetables do have nematode-resistant varieties, but what I wonder is this: will the nematodes continue to infect these varieties and spread further through the soil, even if the crop is relatively unscathed?
I have root knot nematodes, my worst affected vegetable is carrots. When I started gardening here it was almost impossible to grow any carrots. Now I can grow some, they are not ideal carrots, but good enough for home use. There are still some affected, but most are clear from knots, if they survived baby stage. What I did so far to fight them:
Adding home made compost every year
Try to keep soil weed free even when no vegetables growing on the bed(between late summer and spring)
After summer crop is done, saw mustard seeds, let it grow till it starts to flower, then crash it with weed wacker and dig in the soil, water, cover with plastic. The mustard greens release gas that works as fumigator.
Used beneficial nematodes ones (didn’t see much difference after it though)
5)(didn’t try it yet, want to try this fall) Use mustard powder to make water solution and use it as fumigator.
Keep in mind, that nematodes can spread with tools.
Texas A & M recommends planting a cover crop of elbon rye (not ryegrass). The nematode gets trapped in the roots and dies. It also helps to kill some when the elbon rye is plowed under. It helps control them, does not eradicate them.