Nematodes in my veggie garden

marti8aAugust 5, 2008

I just dug up my green beans and found out why I was having a problem with them. The roots were distorted with nematode damage. Now I'm wondering if I should plant the corn or not.

How do you get rid of nematodes?

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suze9(z8b Bastrop Co., TX)

I have problems with root knot nematodes (RKN) here too.

I don't grow corn, but a quick google search indicates RKN can be a problem for it. Based on that, in your shoes, I would probably plant it in another area if you can, somewhere where you have not planted any host plants for RKN recently. Let that spot either lay fallow for a while, or plant something else in it that is not a host plant for fall crop. Also be sure you get up as many of the bean roots as you can - don't leave any in the soil if you can help it.

How do you get rid of nematodes? You can't - wish it were that easy. I've found it is possible to control them and keep their population down enough to get a good harvest, though. Some ways to do it include:

Soil solarization (w/clear plastic). Problem with that is you can't use the area while it's being done, and it needs to be done for at least a couple of months in hot weather. For example, you could solarize that area starting right now, then have it ready for planting something in spring. The soil below the plastic also needs to be kept moist the entire time.

Amending soil regularly with plenty of organic matter. Especially helpful if you have sandy soil, as RKN like sandy soils and easily move through sand, grain to grain.

Rotation. Don't plant any host plants in an area more than once a year if you can help it. For us in Tx, that means no spring *and* fall crop in the same area. Even better, leave an area fallow (or only planted with non-host plants) for an entire year (12 months) or even longer if you can.

I've also found mustard powder to be helpful, when used to pretreat the planting hole. The benefits of using mustard are for RKN management are fairly well-documented (imo, anyway), if you do a google search. I originally got the following suggestion from nandina, who occasionally posts on the tomato forum and has been experimenting on how to deal with nematodes in her own garden for years. She wrote: "At planting time place 4 tablespoons of powdered mustard in the plant hole around the roots. Water and then fill in the planting hole with soil. Top dress with mustard, scratching in around each plant once a month. Powdered mustard can be purchased by the pound from on-line spice stores such as Penzey's for a reasonable price."

Commonly offered suggestions by extension services are to plant elbon rye or certain marigolds as cover crops, but I think you'd be better off trying a couple of the above suggestions. They really don't help that much, imo.

I've also been using a product called Dazitol (google it) with a fair amount of success. Dazitol is mustard and capasium (hot pepper) based.

Nandina also suggests that adding sugar to the planting hole can be helpful, but I have not gotten around to experimenting with that yet. "Toss granulated sugar heavily over that section and water in. As you dig in each plant put a generous handful of sugar in the planting hole around the roots. Finish planting and water in each plant. Once a month top dress and scratch in several handsful of sugar around each plant." Use of sugar is also documented, and you can find out more about the "why" by doing a google search.

Some host plants off the top of my head: tomatoes, bell peppers (not hots and usually not sweet non-bells/frying types), cucurbits, beans, basil. There are many more and this is by no means a comprehensive list.

One more thing - RKN like warm soil temps, and really start to multiply when soil temp in the spring gets and stays above 60F for a while. Because of this, you'll usually tend to see more problems with them later in the season. Along those lines, mulching thickly to keep soil temp low as long as you can helps, so does getting spring crops in early.

    Bookmark   August 6, 2008 at 8:27PM
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Good information suze. I found a website last night but didn't bookmark it (of course) that said to also till during the winter & the nematodes exposed will die.

While I was looking for that website, I found a couple of others with some of the same things you mentioned, plus more.

    Bookmark   August 7, 2008 at 1:40PM
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Glad to see I am not alone with RKN in the veggie garden! I decided to go organic and wow the problems started! The past couple of years we had a hard time with tomato, cukes, Wax & green beans, zucchini & yellow squash, beets and read up on RKN. The yellow and zucchini squash was hit the hardest. First year we didn't plant merigolds between the plants so they must have worked in the past.
Hubby and I are trying the elbon rye as a cover crop this winter AND looking for the N listed on disease resistant varieties with seeds for next spring. Farmers in this area know what works and don't want to give out their secrets, (probably a load of chemicals,) I'd like to try the sugar .. but we have a bad ant problem here...? The ground Mustard in the planting hole does help, I tried it. We sprayed NEEM oil on the soil after we pulled up the plants, and took the infected and good plants to the local dump.. we used to compost them, not anymore! Farmers told me our area is bad for RKN. I hope you all keep posting and let us know your success stories and also what doesn't work! I'll do the same! Keep warm! R

    Bookmark   November 9, 2008 at 9:38PM
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suze9(z8b Bastrop Co., TX)

Commercial growers can still sometimes get critical use exemptions for methyl bromide (even though it has formally been phased out) and also have a few other "chemical" options left that are not available to the home grower. Plus, many of them grow determinate hybrids (frequently also N tolerant), and will also tend to rotate their crops.

I don't think most commercial growers here treat their tomatoes as a mid-summer crop by any means; they tend to harvest early, and by the time population of 'todes has built up to a damaging level in the soil (warm soil temp doesn't help) they are pretty much done reaping their determinate harvests.

Much of what we tend to see here that gets passed off as "vine ripe or Texas grown" during the summer at farmers markets, roadside stands, etc. were probably grown somewhere else and are frequently as tasteless as what is at the grocery, although there are some notable/occasional exceptions. Some farmers markets don't have strict regulations in place as to reselling, wish more did because this is of benefit to both the buyer in terms of quality and the sellers trying to offer a good product and make a reasonable living. But I digress...

As far as trying the sugar, I've not done it yet, but my understanding is that it does not cause a problem with ants - although one would tend to think so. I have used molasses in the garden as an amendment before, and can say I have not seen any more ant problems than usual as a result of it.

    Bookmark   November 9, 2008 at 11:16PM
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There are predatory soil fungi that trap nematodes but I don't know that any of those are commercially available. It would be worth a search though.
I have read that French Marigolds (Tagetes patula) are best for nematode control and they work by trapping the nematodes. The nematodes enter the roots but can't complete their cycle and so die. The marigolds have to be planted thickly to make a real difference. Ideally they should be planted as a cover crop for several months to reduce the population of nematodes. You might consider leaving your garden fallow for a year with marigolds covering the whole area while you grow tomatoes in pots. Or planting alternate rows of marigolds and veggies.
I wish you good luck. I had RKNs at a rental house I lived in for a few years. It seemed like I couldn't grow anything in the ground. That's how I know that you can grow some nice tomatoes in pots.

    Bookmark   November 15, 2008 at 10:33PM
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lou_midlothian_tx(z8 DFW, Tx)

I have read that elbon rye do a good job of controlling nematodes and provide enormous amount of organic matter in the soil as well due to massive root system...

    Bookmark   November 16, 2008 at 9:32AM
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I didn't have any nematode problems the first year I had the garden, but toward the end of the season I did have some fire ants move in. So last spring I bought some beneficial nematodes and poured on the ant mounds. Now I wonder if that brought them in, or if it just took planting beans to find the little buggers.

    Bookmark   November 17, 2008 at 11:11PM
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suze9(z8b Bastrop Co., TX)

marti8a, I doubt your addition of beneficial todes had anything to do with it. They were already in your soil (the bad ones), and growing host plants (beans) multiplied the population.

lou and verdant, (some) marigolds and rye can certainly help out (don't get me wrong), but there are better solutions, which I've mentioned above, like the mustard powder and dazitol. The marigold and rye advice is somewhat outdated (used to be the best known solution available to the home gardener), even though that is still what many extension services choose to push for whatever reason.


    Bookmark   November 18, 2008 at 2:55AM
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I have been reading this post and I am wondering if I need to do 'something' to my garden area. Other than a few tomato plants each year it has been fallow for years. We are spending this winter tilling in as much organic material as possible. How do you apply dry mustard to several rows of beans and corn, etc?

    Bookmark   November 18, 2008 at 6:57AM
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suze9(z8b Bastrop Co., TX)

mla2ofus, have you seen any evidence of root knot nematode damage (galls) on the roots of your tomato plants when you pull them at the end of a season?

    Bookmark   November 19, 2008 at 9:00PM
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We just bought our house in July so I haven't planted anything myself but all my sister ever planted is tomatoes. We bought her house when she moved. She has never mentioned any problems with the tomatoes. I plan on planting beans, curbits, corn, etc. We have calechi clay so we are tilling in as much organics as we can. I will try the dazital on the most suseptical plants just in case, plus plant lots of marygolds 'just in case'.

    Bookmark   November 20, 2008 at 8:38AM
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suze9(z8b Bastrop Co., TX)

If she didn't have problems that you know of with her tomatoes, then you probably don't have RKN in your soil.

Also, if you have a clay soil *and* live in a 7b (central Tx, metroplex??), then it is highly likely that 'todes will not be a problem for you there.

I doubt any sort of nematode treatment will be necessary in your case. A word of warning about the marigolds: I avoid planting them anywhere near my tomato plants because they are host plants for thrips (which vector tomato spotted wilt virus). Spider mites also love them.

    Bookmark   November 20, 2008 at 6:08PM
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dchall_san_antonio(8 San Antonio)

Root knot nematodes is one pest that I never see written about in the organic forums. I think it has to do with predation by other soil microbes.

    Bookmark   November 22, 2008 at 11:56AM
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suze9(z8b Bastrop Co., TX)

"Root knot nematodes is one pest that I never see written about in the organic forums. I think it has to do with predation by other soil microbes."

Hi, David.

(1) Most folks just don't have problems with root knot nematodes, which I suspect is likely a large part of the reason it rarely if ever comes up on the SCM or organic forums. The vast majority of folks I see talking about it and looking for solutions are in California, S. Central/S. Texas, or Florida. And almost all of them are asking in regards to tomatoes.

This topic only infrequently comes up even on the tomato forum, and like I said above, it is usually folks in those areas (and they almost always have sandy soil).

(2) Additions of OM can certainly be helpful, as the 'todes (RKN and stubby) love sandy soil and easily move from grain to grain in sand. But - it is not a cure by any means, and will not completely get rid of them. There is definitely also some value to your statement that "other" soil microbes can help. But again (my experience) it helps, but is not a cure.

About the best practical information I've seen on the subject for the home tomato gardener (in my opinion and experience) has been posted by Nandina over the years in the tomato forum. She has experimented with this quite a bit, done controls, etc. Her suggestions have been to try mustard powder, sugar, and she also suggests castor oil - says it is very much worth trying, but of course it can be $$$ for more than a few tomato plants even if one buys it in bulk. I usually grow 150-200 tomato plants a yr for spring crop, so the castor oil may be impractical for me, other than as an experiment to try out on a test bed of plants. I'll play around with the castor oil next spring in one of my beds to see if it helps.

I have also heard positive things about using yucca (as a soil drench) or actinovate in a 'tode infested area. But - I have not personally tried a yucca drench. I did try actinovate this yr in a couple of beds to see if I thought it was helpful in suppressing or controlling the 'todes, wasn't for me.

Anyway, as I mentioned earlier in this thread, Dazitol (organic - mustard, pepper based) and mustard powder work very well when compared to the other methods I have tried so far. I do also amend the beds well in the fall with as much organic matter as I can get my hands on - this yr, it has been boatloads of shredded leaves.


Here is a link that might be useful: My tomatoes and other veg

    Bookmark   November 24, 2008 at 1:08AM
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Thanks, suze 9, for sending me an e-mail that this discussion was ongoing here on the Texas Forum. Root knot nematodes are a pain in the neck! My thoughts on the subject:

1. Granulated sugar does work. It is possible to substitute the less expensive dry molasses for sugar.

2. Mustard powder also works. In addition I have had excellent results selecting each spot in the fall where I intend to plant a tomato plant next spring. At each of these spots, in the fall, I plant one of the large growing Japanese red mustard plants and allow them to mature through the winter. At tomato planting time I cut back the mustard plants, leaving the roots in the ground and plant each tomato plant tightly to a mustard root, then lay the large mustard leaves around each tomato seedling as a mulch. If I were growing 200 tomato plants I would seed my rows in the fall with the mustard, thinning as needed so the mustard plants could develop good root systems. Note: it is likely that area box stores may still have some of these mustard plants in stock in which case there is still time to plant them now and try this experiment on a small scale.

3. I am doubtful that a yucca drench would work as yucca is mainly just a non ionic surfactant. However, if one were to dissolve sugar (dry molasses) into the mix, it might be effective. I would try a mix of 2 cups sugar, 1/8 cup yucca extract to a gallon of water. Worth a try. Or....

4. Speaking of surfactants, there is a new organic one on the market easily found at Wal-Mart and Target in the dishwashing soap department. The name of the dishwashing liquid is METHOD, the type with no fragrance or dyes is called 'Go Naked' and it is derived from seaweed. It has twice the amount of surfactant as other dishwashing liquids so you do not have to use very much for it to be effective. This could be substituted for yucca.

    Bookmark   November 24, 2008 at 3:40PM
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suze9(z8b Bastrop Co., TX)

Thanks so much for the additional information, nandina. Very pleased you had a chance to chime in. :-)

And - glad you posted on the use of actually planting mustard plants and leaving the roots in or close to the tomato hole - or in the rows, because I very vaguely remembered you mentioning that before on the tomato forum. But it has been quite a while, and I couldn't find that info in older posts (or google cache).

I thought I would mention a few tasty tomato varieties that I've found have good to great RKN tolerance:

Momotaro - I've grown 100's of vars, but never got around to this one until this yr for fall crop for whatever reason. Yum - terrific flavor! Quite the pleasant surprise. Sweet, yet rich and complex. Good production of mostly tennis ball sized toms. It's a hybrid, and has been "tested/certified" for N tolerance.

Yasenichki Yabuchar - not commercially available at this time, but I have seeds if anyone wants to try it. It is open-pollinated, and my observations on nematode tolerance are strictly antecdotal. But - in a 'tode infested bed, I left a plant in from spring crop and just got around to pulling it a couple of days ago. The plant was an absolute monster (grew all the way up and back down a 6' Texas cage, plus some, and was about 5 ft wide before my first light frost took it out). It was too big to protect, so I picked all the breakers and partial ripes I could before that happened. Very good to great flavored med sized red tomatoes, a great main cropper type, also sets well in heat. All said and done - this var gave me at least 150 nice toms from one plant. The roots had almost no galling at all when I pulled the plant. A very vigorous plant to say the least. At the largest part of the base, the stem made it to almost 7" in diameter, and got sort of woody. Roots were extremely large, most of them as thick as my pinky finger - had to dig this one out with a shovel.

Mountain Princess - Another var that seems to have a fair amount of 'tode tolerance (based on my antecdotal observations, again OP, so not certified/tested). Very good flavor. Similar observations on the roots to Yasenichki when I pulled the plant.

I like to grow a lot of different vars, and doubt I will strictly limit myself to only N tolerant vars anytime soon. But - I thought I would mention my observations in case anyone finds it helpful.

A couple more (hybrids) that exhibit good N tolerance are Sungold and Sweet Quartz. I love Sungold, and wouldn't be w/o it, Sweet Quartz is also good, especially if you like a sweet cherry type. Big Beef is also a good one - admittedly not an 8-9-10 on the flavor scale for me, but then I'm kind of picky. Good to very good flavor, high production of med sized red globes. Better than many other hybrids for taste, imo.

    Bookmark   November 26, 2008 at 1:30AM
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