As a southern gardener, I know the frustration of nematodes. You cannot erradicate them but there are things you can do to avoid them and/or reduce their damage.
Many garden veggies aren't affected by nematodes. Some varieties, such as tomatoes with a VFN after their name, are resistant. Whenever possible, choose these for areas with nematode infested soil and plant susceptible species, such as okra, in areas that may not have nematodes.
Grow nematode "trap crops" such as 'Elbon' cereal rye in winter and marigolds in summer to reduce their numbers. Make sure and plant these as a solid cover, not just a plant or two here or there. The idea is to fill the soil with the roots of the trap crop. At the end of the crop's season, mow it down and rototill it under, allowing the green matter to
decay in the soil.
Summer plowing can help reduce nematode numbers. In the heat of summer, plow an area and let the surface dry for a week or so. Then plow again and let dry. Nematodes die when exposed to the sunlight and drying conditions.
Summer solarizing can also help. Rototill and water an area of the garden. Then cover the soil with clear (not black) plastic and let it "cook" for about 6 weeks of hot, sunny weather. This will pasteurize the upper few inches of soil, reducing the nematode population. If it rains during the solarizing period, sweep rain puddles off the plastic when the rain is over. After solarizing, do not rototill prior to planting or you'll be bringing nematodes and weed seeds up to the surface from deeper areas.
A final tip is to plant susceptible crops in containers filled with a good growing mix.
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