Way back when me and my son did the required Science Fair project on root knot nematodes. He received an A grade plus an honorable mention. 20 years ago. We had a control group of do nothing,fumigate with Vapam,co-plant with Marigold and add massive amounts of compost/organic material. The Marigolds were not the little border plants but the big tall Inca giants. The compost had alot of Sargasso Sea weed and the Vapam is of course Vamapam a fumigant. This Science experiment worked out well for a whole generation of my offspring. Vapam worked best of course but the co-planting of Inca Tall marigold almost rivaled that of the heaviy composted area. The do nothing plot gave us root knots that Pres. Jimmy Carter would be proud to call a peanut crop. The co-planted Inca Tall marigold plot almost equaled that of the heavly composted area. The Vapam area of course ruled the years of experiments. During every year of the experiments we used the "Delicious" variety tomato. We got some real whoppers over the years. That is my story and I am sticking to it.

Oh, now that things are getting back to me; after clean-shaving all the roots and treating with bleach, I also scrubbed the root-stub with a tooth brush under running tap water... As I mentioned many times before, PREVENTION is the best cure! Do examine ALL rooted figs you get from who-ever. If RKN ever get into ones garden soil, it is extremely difficult to eradicate them, no matter how many RKN- trapping-marigolds are planted, RKN-eating-good- nematodes (expensive) are applied, or chemicals used. There is one chemical that nukes the soil (it practically kills everything!). I forgot the exact name. But it SO toxic, that it is now illegal and not available any more.

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

I can't find the memory stick the scans are on (I moved), and the ARS annuals are boxed in the garage, but in the seventies or eighties, there were at least two articles in the American Rose Annuals about the use of ground pine bark cleaning root knot nematodes from the soil. It was used both as an amendment, mixed in the soil as well as a mulch. Previously infected soils and plants were found to be "cleaned" of the infestation simply due to the cleansing action of the pine bark. You might consider using it if it's locally available in your area. You might also search this forum for the scans as I am sure I have posted them within the past two years when the nematode question was raised previously. Good luck.