The marigold you would use is french marigold, that is the most common marigold found. However marigolds will not eradicate the nematodes only cut down on them.

They probably came with that plant if you bought it and didn't spread to the others soon enough to show enough damage, but no doubt they have spread throughout the bed.

There are nemicides that you can buy, but I don't know what the long term affect on the soil is. Solarization of the soil is the recommended treatment. Spread compost on the soil and cover with plastic. You need lots of hot sun to fry these vicious little worms. I know solarizing the bed will lose you valuable growing space, but maybe you can rig up some pots to replace that bed.

how many years have you planted in the same hole???

wouldnt crop rotation help ?

ken

This is my DH's veggie garden and I have no say so over the placement of his plants (I do ornamentals). I know he moves his plants around from year to year and in the 20+ years he's been doing so I've never seen any serious indication of root knot nemotodes until this one tomato plant.......I fear oilpaint is right. That they came in on a store bought plant. You always have this fear in the back of your mind when you don't grow things from seed yourself about what you may be importing into your soil, but there's just not room enough to start everything from seed inside the house.

I'm afraid that there are no traditional chemical nematicides on the market for the general population...thankfully! They are exceedingly toxic.

There are some organic products on the market, but none that are packaged for retail sale, as yet.

I doubt very much that your tomatoes were the cause of the nematode infestation. They were grown in a soil-less potting medium, in little containers, just like you would at home. The potting mix isn't re-used as it's all in the cell pack. Commercial potting mixes are considered sterile and free from pathogens. Unless you are purchasing your plants from a local source who grows their seedlings in the ground, there's little chance of bringing home nematodes with you.

Root knot and other plant parasitic nematodes are plentiful in soils all around the world. As you well know, root knot nematode is very commonly found to be a problem with tomatoes. Yes, it's the little French marigold varieties that appear to be most effective against those particular little guys, as well as some of the other pest species, too.

Treating an area with marigolds will require that you lose a growing season, unfortunately. At least in the location you wish to grow tomatoes or other nematode attractive plants. The marigolds have to be sown rather heavily, like a cover crop, over the affected area. The following season, that specific area should have a much, much lower population of nematodes and can be used safely. You don't have to put your entire garden area under a bed of marigolds (unless you want to), just that location where tomatoes, peppers, etc. are intended for future plantings.

Remember, you can't just plant a marigold fence around the tomatoes (darn it all), nor does scattering a few plants here and there (called intercropping) seem to be helpful. Intercropping, by the way, CAN be very useful in controlling early blight!

Nematodes travel, albeit slowly. You might need to treat that area again the following season. It's wise to move plants from one year to the next, and the same goes for the marigolds.

Soil solarization is something of an exacting procedure, but is successfully used for a variety of soil pathogens. Nematodes are more tolerant of heat than most of the other things that solarization may kill, but can still be helpful if done at the right time, the right way, and for as long as it takes for those critters to boil! There's sure to be lots of good information on the Web about how to get the job done, but if you have any trouble, let me know.

Here is a link that might be useful: Using marigolds to help control nematodes

Thanks so much Rhizo. You have been most informative. I see that Parks has the nematode type marigolds, so I will order from them. Fortunately, the spot this heavy infestation was in was off to one side of his major veggie growing space, so covering this area with Marigolds for a season won't be a problem. In theory this may work if he will keep the bermuda out and the other weeds picked (he's not good at weeding)...... The tomato in question was Early Girl, and I now notice it doesn't have an "N" in it's resistance description. I'll make sure that the next variety we plant there does.....I sure wish I'd been able to find a mail order vendor for Elbon rye, but alas I couldn't. That would have been a two pronged attack for sure. I don't want these things spreading to my ornamentals........ Thanks again for all your help. Fingers crossed.

Fingers crossed for you! If you think about it, let us know the results of your work.

By the way, it might very well be worth your while to contact your local extension office about the rye grass (Elbon). There might be some local distributors, since it's an Oklahoma introduction.

Rhizo, you are a fount of information! I would like to hear more from you about early blight. Are you saying that marigolds help this? Early blight was my number one problem with my tomatoes last year. It seems to be rampant in our area.

It's been shown, in several studies, that marigolds have an allelopathic effect over the spores that can cause early blight. Rather than using marigolds as a cover crop for a season, they can be intercropped amongst the tomato plants. In one report I read, they used African Marigolds (really from Mexico), Tagetes erecta, rather than the small French cultivars, Tagetes patula, used for nematode reduction.

It sure is worth some experimentation, and I know that I'll be trying it this year. I don't ordinarily grow marigolds because they need to be deadheaded so frequently, and they are SUCH a spider mite magnet.

SO, along with the usual housekeeping tasks to help keep early blight at bay, African marigolds might help to prevent infection, too.

Rhizo: I called our County extension office last fall. The "Master Gardeners" run the show there for home owner inquiries. A good program for people who want to learn a little about a lot of gardening subjects. Elbon Rye wasn't one of the things this gentlemen knew about......Speaking of spider mites and tomatoes...We lost our tomato plants 2 years in a row from Spider mites. Again, I'm not a veggie person so I really wasn't paying attention to DH's crop failure issues. When I did I saw what the culprit was. To make a long story short, after research, I found that Floramite (a miticide) has been approved for tomatoes. It's dreadfully expensive (like hundreds of dollars), but from all reports I've heard it works. It's available from Rosmania. In our case my dh, once aware of what was going on with his tomatoes, was able to culturally minimize spider mite damage last year and we had a nice crop of them...For control of spider mites on ornamentals, Avid has done the job for me for years. But it must be used sparingly or resistance issues crop up. I think I used it 3 times all of last year. It will work on the patch of nematode marigolds if they get bad enough that I think it's worth spraying.

Thanks for the information, Maryl. I don't use chemical pesticides at all, and have rarely felt the need to. Others might find your information useful.

Rhizo: I don't know what the composition of Floramite is as I never investigated it. However I did investigate AVID for ornamentals when I first became aware of it in the 80's. It is a targeted pesticide for use on spider mites, leaf minor and is somewhat effective on adult Thrips. It is NOT an indiscriminate pesticide. I don't know what you term "chemical", but I know some people call themselves organic but still use pesticides such as soap, neem oil, BT etc. AVID for spider mites may be suitable for those folks as the active ingredient 'Abamectin' occurs naturally and is derived from the soil micro oranism Streptomyces Avermitilis. Personally I think of it about like Bacillus for catapillars. But I must reiterate, it is NOT for edible crops and ONLY for ornamentals. It should never be used as a preventative but only when damage is evident. Resistance problems from overuse have occured, so only use it when you must. I'm not trying to sell AVID but it was like a magic bullet for my spider mite problems on ornamentals all those many years ago, many of which I could not grow today if the spider mites went unchecked from year to year. And no, I seldom spray anything other then AVID during the growing season.....I'm not trying to persuade anyone to use anything that will cause them a sleepless night, but knowledge is power and AVID just may fit the bill for conscientious ornamental growers with a spider mite problem.

Were you under the impression that I was questioning your choices? I wasn't. I'm glad to know that pesticidal products (including home remedies and 'organic' products) are being used by responsible consumers.

One thing, though, just to clarify something. Though abamectin is a bacterium product, it should be used with the utmost caution. It is a broad spectrum pesticide, lethal to a wide range of beneficials including bees. There are abamectin products labeled for caterpillars, beetles, wasps, ants, and a wide range of other 'pests'. Even at normal rates, it has proven to be highly dangerous for many species of fish.

That makes it quite different from the Bacillus products commonly used to control caterpillars, beetles, or mosquitoes/flies/gnats.

I hope you find a good source for the ryegrass. Were you going to use it for a fall planting, spring planting? I saw that some of the usual seed houses were selling it, though I didn't notice if it was for last season or this year.

No offense taken at all. My knowledge and 20 years of experience is specifically with the miticide AVID. For those wishing to grow something other then mite food, it is effective on ornamentals WHEN benign/organic cultural practices fail. Personally I hate spraying, so if a spritz or two of water will do the trick, that's fine by me...I didn't locate Elbon rye at any of my normal mail order seed sources last year. I did locate it at a farm store about an hours drive from here, but only in a 50lb bag. If you ever run into someone selling a pound bag or so of it mail order I'd be tickled to hear about it. I thought sure I'd run across it in my search last fall at the organic mail order sites, but I sure didn't.

Well, how about that. I will definitely give the African marigolds a try. After all, what harm could they do, and they should at least look pretty. Thanks for the info, rhizo! :)