Try this link, I think that there are only 200 or so plant including Nightshade plants like tomatoes, also Fig trees can be hurt by RKN. Clay soil & block walls make it hard for RKN. There is a predator Nematode that will help bring the RKN under control. Here is a link that might be useful: RKN resistant plants

Dale, In general, garlic is considered a poor host for nematodes (as is corn), so often it is recommended that you plant garlic in an area where you have a consistent root knot neamtode problem. So, in general, garlic ought to do passably well in areas infested with RKNs. However, if you have a very heavy infestation of RKNs, even garlic can be stunted and less productive. You won't know if the RKNs in your soil are at a high enough level to affect your garlic harvest until you try growing garlic there and can see what results you get. I doubt you have enough nematodes to affect garlic, but I could be wrong since I don't have nematodes here and my experience with them is from long-ago in Texas. If you have dealt with RKNS before, then you already know all the practices that will help. Unfortunately, one of the best techniques is to grow Elbon cereal rye in the cool season, but you can't do that if you're growing garlic. If it were me, I'd work to change the soil over time in the same way that you have been. I'd add as much manure and compost as possible, as well as sugar or molasses to stimulate microbial action. Although chitosan's cost can be prohibitive when trying to rehab a large garden, it might be worth it to you to purchase some and add it to your soil where you intend to plant the garlic. Or, if you have access via seafood restaurants to shellfish shells, you could compost your own to get the same effect. There is evidence that tilling in pine bark fines about a month before planting can help reduce damage from RKNs. If it were my garden, I'll try the solution in the attached link, but I haven't tried it and can't vouch for its effectiveness. As with all plant diseases or pests, resistance is only resistance and not immunity. I doubt total immunity exists in any variety of a RKN host plant although, of course, in non-host plants like carrots and lettuce, I'd think you'd have total immunity since they don't host the little RKN brats. Good luck, Dawn Here is a link that might be useful: The Gardens Alive Solution to RKNs

Jo, Like Larry, I've never seen any quantifiable independent research that shows neem oil applied to soil has any effect on nematodes, although I have seen such claims made by those who benefit from selling neem. I would never apply neem to soil because it likely would kill some of the good microbes in the soil which then would leave your soil less healthy. Remember that healthy soil is full of all kinds of biologically active creatures, which I tend to lump together in a group and call "microbes". What are these microbes and how many are there? The microorganisms include all sorts of microscopic plants and animals, including nematodes (there are beneficial ones, you know), fungi, actinomycetes, bacteria, yeast, germs, protozoa and algae. Healthy soil that has a good compost/humus content is believed to have as many as 50 billion microbes in 1 tablespoon of soil, according to organic gardening expert and author J. Howard Garrett, aka 'The Dirt Doctor'. Since all the microbes in soil play an important role in soil health, you don't want to put anything in the soil that would hurt those microbes. I'll use spider mites as an example of the unintended consequences of using a 'cide' to kill the bad pests and inadvertently killing beneficial insects too. While spider mites are a pest in certain circumstances, there are beneficial predatory mites that help keep the spider mites under control. When you spray a miticide on plants infested with spider mites, you kill not only some of the spider mites (most pesticides do not kill 100% of the pests) but also the predatory mites that help keep the number of spider mites down. When the mite population rebounds (and it always does), the pesky herbivore spider mites bounce back first because they feed on plants and plants are readily available so they have an endless food source. Then, in a much more slow manner, the predatory mite population, which are carnivores, rebounds. The problem is that beneficial insects rebound very slowly because the 'mamas' don't reproduce until there's already a good food source for their babies to eat. So, while the mama predatory mites are waiting for the food source to increase to the level they need, the spider mite population is growing very rapidly and getting out of control. Once the predatory mite population begins to surge and feed upon the spider mites, the spider mites have a huge head start and your plants are severely damaged. I think if you used neem in soil, you'd likely kill off a good portion of the microbes in the soil, leaving your soil less healthy, less fertile and more vulnerable to soil-borne pests, including root knot nematodes and various soil-borne diseases. So, even if the idea of trying neem is attractive, it could hurt more than it might help. I used the spider mite example to illustrate how using a 'cide' for pest control can backfire because it is the story of my life. My dad was a terrific gardener, but he fought spider mites my entire childhood, and he lost that battle in late July or so of every year, and so did his best gardening buddy, Mr. Camp. I watched the two of them try everything to kill those spider mites, but the spider mites always outlived and outlasted their efforts. So, I grew up thinking that no matter what you did, you would lose your tomato plants to spider mites in July. Eventually I grew up and had a home of my own and my own garden. During our second year in our house, we decided we wouldn't 'poison' our tomato plants with the miticide commonly sold to home gardeners back then. A miticide didn't help the first year in our new home when we did use it, so it seemed pointless to spend money buying it and then spend time spraying it on the plants the second year. What happened? Our spider mites didn't get out of control and our tomato plants didn't die. Once I convinced my dad to give up miticides, he never lost his tomato plants to spider mites again. Still, it probably was another dozen years or so before I finally understood why not using a miticide saved our plants from the mites, and that's because I didn't know back then that there was such a thing as predatory mites. So, I hope that tale illustrates the dangers of even attempting to use a soil treatment to kill the root knot nematodes. Even if it would kill the nematodes (which I highly doubt), it would kill all the other microbial life in the soil. As an organic gardener that is absolutely the last thing you need. Even worse, what I think most likely is the neem oil would kill the good microbes, but not the root knot nematodes. When I am trying to figure out what to use in my garden or landscape, I fall back on that old adage used by physicians.... "first, do no harm". You might have a chance of killing some of the root knot nematodes by applying beneficial nematodes to the soil. The most important factor affecting the efficacy of beneficial nematodes would be to apply them at precisely the exact temperature they need, and also to use the right beneficial nematodes. Dawn

Kimmq, I went with Huma Gro Thyme oil based Promax. I am hopeful that it gives me a zone of sterility because that I can influence in a positive way re soil biology after the disaster. I understand more clearly why my mid season application of pure sulfur had a good effect. I would rather have good roots and crappy leaves than the other way round.