Some recommendations that taste good:
Sungold
Big Beef
Mortgage Lifter VFN (this one is OP, you can save seeds)

Add lots of organic matter to the soil every year as well.

I would do container gardening.

there is a container forum.

Here is a link that might be useful: Container Forum

I also think it's good to recognize that there are NO resistant
varieties to RKN's rather, it's a tolerance...

is not a factually correct statement.

There actually is true resistance to root knot nematodes however the
resistance from the commonly known Mi gene breaks down when soil
temps get above 80°F and true resistance is not seen in some
geographically isolated populations.

There are also new gene sites which have been located which confer
resistance to both cyst nematodes (Globodera spp. and Heterodera spp.)
and root-knot nematodes (Meloidogyne spp.) by a different mechanism than
the Mi gene.

Rotation with monocots, grasses, can reduce populations.

(SEG)

I also think it's good to recognize that there are NO resistant
varieties to RKN's rather, it's a tolerance...
is not a factually correct statement.

(There actually is true resistance to root knot nematodes however the
resistance from the commonly known Mi gene breaks down when soil
temps get above 80°F and true resistance is not seen in some
geographically isolated populations.)

*****

Agreed, to a point, but RKN's are only a problem in very warm weather areas where the soil doesn't freeze deeply and I'm sure the soil temps in FL and CA and GA along the Gulf Coast where RKN's are most prevalent must be above 80 F most of the time in the summer.

(true resistance is not seen in some
geographically isolated populations.)

John, with this comment I can agree more as to tolerance to RKN's, but I'm not so sure I could define what you call geographically isolated populations since the mi gene is bred into the plant and is not a gene found in the RKN's.

Do you see what I mean here? As in what is a geographicaolly isolated population of tomato plants?

Carolyn

Thanks for all the info!!! And thanks Suze9 for the Varieties list.
I understand that "resistant" does not mean nematode "proof"!
I am growing in containers, and realize I could just remove ALL the soil and start over, and may do so at some point. (the possibilty of enrolling my husband into THAT job right away is not very likely!! :-) ) But for now, I want to amend with organics, plant marigolds as companions, and try resistant varieties to see if I can save the soil I have been working on for 2 years to get going.
I think I know how the nematodes got there. I added some sandy oak leaf rich soil from the woods I gathered which I was thinking would help add some sand and minerals to my boxes. BIG MISTAKE!!!
Ha!!! live and learn!!

At issue here is not geographically isolated tomato plants. It is geographically isolated populations of nematodes.

One would think that a PhD in microbiology would know and understand that quickly reproducing and particularly isolated populations of organisms have the potential to adapt and overcome simple single gene sources of resistance via selection.

But look in your disease compendium you often consult, the part about nematodes and bring up further debate on that with Dr. Overman (who actually is an expert in this area).

While consulting the disease compendium, look in the glossary at the definition of resistance these researchers have applied. Note the use of the word "impede" in their definition which doesnÂt imply just "stop". Mi is considered RKN resistant when temps are below 80F by experts who actually work on tomatoes.

Others can simply think of applying the term resistance to other diseases or pests when thinking about a camera or device which is labelled "water resistant". It doesnt mean it is "water proof". Fusarium resistant plants simply impede the progression of the disease not stop it.

At issue here is not geographically isolated tomato plants. It is geographically isolated populations of nematodes.

*****

John, we simply are not communicating and quite frankly you're begiining to sound more like the Keith I know rather than the John I know.LOL

I've linked below to an article about the origin of the mi gene. It was transferred from one of the tomato species, L peruvianum, to tomato plants.

The gene is not present in the nematodes, so how can there be isolated populations of nematodes where tolerance might break down when they don't even have the gene?

(One would think that a PhD in microbiology would know and understand that quickly reproducing and particularly isolated populations of organisms have the potential to adapt and overcome simple single gene sources of resistance via selection.)

Yes, one would assume that to be true.( smile)

Carolyn

Here is a link that might be useful: gene mi source and genetics

In the original post, Tanya asks "are there any OP that are Nematode resistant?"

For a nematode resistant, open pollinated tomato cultivar, you will have to find one with the Mi gene that confers resistance to root knot nematodes.

Another benefit of a tomato cultivar with the Mi gene is that it will also be resistant against the aphid Macrosiphum euphorbiae as the Mi gene that confers nematode resistance at the root has been show to be the same as the Meu-1 gene that confers resistance to the aphid at the leaf.

Now of course the problem is finding an open pollinated tomato that has the Mi gene. There are hybrids that show resistance to root knot nematodes such as QualiT-21 in California and Sanibel in Florida.

Resistance to root knot nematodes is not necessarily operative in all conditions, however, since it has been shown that incremental reductions in nematode resistance occur with each degree of temperature above 78°F. At 91°F tomato plants are fully susceptible. Therefore a home grower in warm, sunny California might grow nematode resistant varieties in spring plantings when cooler soil temperatures prevail.

Also Tanya indicates she has no room for crop rotation to minimize the effects of nematodes. What a gardener may do in that case is use soil solarization as a nonchemical technique where transparent polyethylene tarps are laid over moist soil for a 6 to 12 weeks to heat the unplanted garden soil to temperatures lethal to nematodes. Then when the tomatoes are ready to plant, the plastic tarps can be painted white to reflect the sun and left in place as mulch against weeds. However, for solarization to be effective, the soil must be kept at a high moisture content during the heating process, which can be done by installing a drip irrigation system beneath the plastic tarps.

Hopefully someone can answer Tanya's search for open pollinated tomato cultivars found to carry the Mi gene.

A penny for your thoughts.

An interesting link about root knot nematodes. It mentions a new treatment in the works involving chitinase, an enzyme that dissolves the "skin" around nematode eggs. The numbers look encouraging. Unfortunately, I'm not sure if or where you can buy chitinase at this time.

I seem to recall reading a thread on here or some other forum that mentioned using ground crab shells and other chitinous seafood leftovers as a soil amendment. I have no link for it. Supposedly, the soil organisms that grow to feed on the crab shells produce should also feed on nematode eggs.

Here is a link that might be useful: Nematodes and chitinase

I seem to recall reading a thread on here or some other forum that mentioned using ground crab shells and other chitinous seafood leftovers as a soil amendment. I have no link for it. Supposedly, the soil organisms that grow to feed on the crab shells produce should also feed on nematode eggs.

******

I have a friend in TX who has tried the crab shell, shrimp shell route and she didn't find that it helped.

That's just one person, though.

And I never did research it at the time and won't be doing it now. I get the impression that many folks who have RKN problems do a bit of Googling. Or maybe I should say that if I had RKN problems that's what I'd be doing.

The chitinase enzyme sounds interesting and I hope something comes of that. At least better than the molasses that I've also seen mentioned and folks saying that doesn't seem to work either. Sigh.

I guess the best I've read about so far that seems to work for some folks is to add lots and lots of organic material to the RKN infested soil to seperate the sand grains, as I think I mentioned in a post above.

Carolyn

A thick layer of a light colored organic mulch could potentially reduce
solar radiation and keep soil temps down into a range where Mi is more
effective.

Some OP's
(there are numerous OP processing types with N)

Amex VFN
Anahu (Univ Hi)
Andino
Atkinson
Calmart
Crown Bee (Aussie variety)
Dona
Feista
Healani (Univ Hi)
Moneymaker Select
Monita (derived from Moneymaker)
Motabo (derived from Moneymaker)
Mossol (derived from Moneymaker)
Motelle (derived from Moneymaker)
Motac (derived from Moneymaker)
Nemared
Nematex
Peto 343
Puunu (Univ Hi)
Ronita (France)
Sunburst
Super Marzano
VFN-8 (UCD introductions)
VFN BUSH
VFNT Cherry

remember also any de-hybridized line will have a 50% chance for having
some resistance - select the resistant ones and you can develop a line.
Since it is a dominate gene one must do so for at least 6 generations.

there is also another "trick" or marker that can help one narrow down
the gene's presence but I cant give away all the good secrets

The gene is not present in the nematodes, so how can there be
isolated populations of nematodes where tolerance might break down when
they don't even have the gene?

Carolyn is really just not getting Overman's point.

which is kinda funny since she's a PhD in microbiology and should
understand the reasoning to changes in populations:

SO I'll try again

the point is REALLY simple.

It isnt the Mi gene that changes. It's the nematode
population that changes.

Here are similar examples.

I am sure you know of antibiotics that no longer work on strep strains.
So it is not the host or antibiotic that has somehow changed. But I
suspect in this case you know it is the strep which has changed into a
new strain overcoming the ability for the antibiotic to work.

When a pathogen overcomes the ability of a chemical spray to work what
changes? It isn't certainly isn't the chemical and in a generation or
two it isn't the host(s). It's the pathogen itself which adapts and
changes to the conditions it finds itself in just like the strep example
above.

Another relevant example with another pathogens of tomato would be with
late blight. LB in some instances has changed (through selection
pressure) and Ridomil no longer is an effective spray in these
situations. It wasn't the Ridomil nor the tomato variety(ies) which
changed so quickly as you seem to be implying. It was the pathogen itself.

So Overman is implying that isolated nematode populations can adapt,
through selection, mutation or both to overcome the host's Mi
genetic resistance.

Mi confers resistance but it is limited to the environment it
finds itself.

So Overman is implying that isolated nematode populations can adapt,
through selection, mutation or both to overcome the host's Mi
genetic resistance.

*****

Now that you rephrase it I do understand. I did not read what Overman had to say, just what you wrote.

******

Carolyn is really just not getting Overman's point.

which is kinda funny since she's a PhD in microbiology and should
understand the reasoning to changes in populations:

SO I'll try again )

And again, I'm glad you did try again John b'c what you wrote at first was not what you're saying now. And without my having read Overman and just what you wrote it was confusing to me.

And yes, there are numerous examples in Microbiology that illustrate the same priciple.

Carolyn

Through some Googling, the following varieties showed up as nematode resistant to one degree or another according to several field tests ... some of the varieties already have been mentioned above in this same thread:

Ace Hy, Anahu, Atkinson, Auburn 76, Best Boy, Better Boy, Big Beef, Big Set, Bonus VFN, Bush Big Boy, Bush Early Girl, Calmart, Celebrity, Champion, Empire, Ensalada, French Rose, Lemon Boy, Magnifico, Meltine, Monte Carlo, Nemared, Nemato, Northern Exposure, OG 50, ParkÂs Extra Early, ParkÂs Whopper, Patriot, Pelican, Pink Saturn, President, Red October, Red Supreme, Rich Reward, Resaplus, Rossol, Spring Giant, Sugar Snack, Summer Flavor 5000, Super BeefSteak, SuperSteak, Supertasty, Surpise, Sweet Tangerine, Terrific, Viva Italia, VFN Bush, VFN 8, Vine Ripe, Winter Red.

I'll leave it to the reader to separate the open pollinated from the hybrid varieties, and to determine for which ones seeds are still available.

tanya47 - a question please. If, as you said above, you are growing your plants in containers already why are you using soil in them? Perhaps I don't understand but since container-grown plants do far better in a soilless potting mix than in "dirt" why not simply replace your container contents with a quality potting mix? Two benefits - no nems and much better plants.

Dave

Hi Dave...I am growing in 4'x4' raised beds/boxes. Not containers, exactly. The soil is about 1/2 topsoil from the garden, and 1/2 amendments such as homemade compost, some bags of organics from the nursery etc.