Q. I was going through my garden notes and I found pictures I took a few months ago of my tomato plants. A few of them came up with real gnarly roots, I have never seen anything like it.
A. This is definitely root knot nematode judging from your photos. There really is no way to totally rid the soil of nematodes. In the past, soil fumigants were used on a regular basis to knock these critters back. Soil fumigants are being eliminated from the pest control arsenal due to environmental concerns.
Your options are to move your growing area to a new location that is not infested, grow in raised beds or containers and use resistant varieties. There are some vegetable varieties more resistant to nematodes than others.
|Roots of tomato plant from reader|
Use varieties that have a capital “N” after their name. This stands for “nematode resistant”. An example would be the tomato, Better Boy VFN which is resistant to Verticillium and Fusarium diseases as well as nematodes.
Build up your organic matter content with lots of compost. Nematodes don’t like soils with high organic matter.
Be very careful of transferring soils contaminated with nematodes to new beds or containers. This includes using contaminated gardening utensils. Make sure utensils are sanitized between locations.
It is possible for this pest to migrate from your existing soil to a new raised bed constructed on top of contaminated soil. You might to consider laying thick plastic underneath the raised bed. Make sure the plastic is sloping slightly for drainage and make the bed at least 12 inches deep.
Here are some links back to my blog where I have written about nematode in the past.