Root Knot Nematode

[Elizabeth]

I think I'm going to cry - I just pulled 2 plants (yellow brandywine and Hillbilly) that had stopped producing and look what I found.

I try to stick with organic methods, but I'm not a purist. I don't want to apply anything really nasty though. What do I do????

Since I have beds that are 3.5' x 3.5' x 14" and are essentially large containers (right down to having bottoms with holes drilled in them) it's feasible (but not fun with a bad back) to remove all of the soil - what to do with it though....

I'm worried... I don't know if the other beds are contaminated. I bought the seedlings at a local nursery because of time constraints so it's possible others came in with it too. I know one bed a couple down is clean - I pulled a plant there and there were no issues.

My little seedlings I started for Fall planting are growing nicely, and I am potting them up in individual pots in the next couple of days - where are they going to live when they grow up? I'm so sad.

[Elizabeth]

I checked where I had more sad looking plants and it looks like I have at least 2 more infected beds. I ran out of shovels so didn't check further.

Does anyone know what kind of sanitation measures I should use to keep from spreading it to clean beds? I want to clean my shovels and cages. I'm even worried about the gloves I was wearing! (LOL) I have never encountered these before, and I'm kinda at sea here.

I did some more research and it looks like chitin (pulverized shellfish shells) is a suggested way to go. From what I can find It can take the better part of a year to reduce the population, and you have to add quite a bit (1%) to the soil, but it's supposed to help by giving chitin eating bacteria a helping hand so they have a population boom. When they run out of the chitin you have added they go looking for more, and it just so happens nematode egg shells contain chitin. Has anyone used this with good results?

While I'm asking questions, has anyone ever used those cloth pots to grow tomatoes? I have to come up with something soon to get my fall plants in, but fingers crossed I won't need a permanent solution, just one to last a couple of years. Then I guess it's strict crop rotation for me from here on out. Sigh....

Here is a close up of the roots. Nasty little buggers.

[Suze]

I use Teracure or Dragonfire with very good results. The active ingredient for both is wild sesame oil. Lately I've been using the Teracure. It's a custom blend that Poulenger does, and is easier to use with my EZ Flo fertigation tank.

These products normally get applied ~1x/month when a susceptible crop is in and when soil temp exceeds 65F. (RKN are not active when soil temp is < 65F)

In addition, I add dried molasses to the beds as an amendment, and throw some in the planting hole as well. Frequent additions of organic matter are also helpful.

Practically speaking, I don't think there is much you can do long-term to keep them from spreading to other beds (nematodes can move several feet a year), but you can certainly try to slow the spread by cleaning your tools after using them in RKN infested beds.

Fall crop can be tough when you have RKN if you are growing in the same area used for spring crop because they have had all summer at those higher soil temps to multiply. Do yourself a favor and use containers for the fall, or plant in areas you did not plant RKN susceptible crops in earlier in the year. And do use something to treat if not using containers.

Rotation is helpful. At the least, try not to use your problem areas more than once a year or the population will tend to explode.

[Elizabeth]

Suze,

Thanks for the information. This is quite distressing for me - I gardened for years then had to take a few years off because of back issues, I'm finally getting back in the saddle and blam, this happens. I'm thoroughly bummed.

I looked up Dragonfire and with that name found a great study of alternative nematicides done by two people from university ag departments that shows it placed second in effectiveness to fumigation, which is impressive. It looks like a useful tool in the arsenal, but zowie, the price! Chitin (crab/shrimp meal) placed a close 3rd. Have you ever tried using that?

I can't find Teracure anywhere - the only mentions of it when I Google Teracure nematicide are links to another thread here and one in the Dave's Garden forums.

I found a chart for proper crop rotation from UC Davis and will start implementing that right away...instead of the lovely garden plan I had spent so much time on for my fall planting...drat!

I have a bunch of new largish pots here and there on patios that I had earmarked for other things, but I guess vegetables are going in instead

Where does one find dried molasses?

Thanks

[Suze]

Elizabeth, I've never used chitin. The amount I'd need + the time and work that it would require to amend all of my 26 raised beds is probably not practical. Also, a couple of people I know did not get very good control with chitin so I didn't bother to try it.

Poulenger is the manufacturer for both Dragonfire and Teracure. (http://www.poulengerusa.com/) Teracure is not on their website for whatever reason, and you'll need to call them to order it. Also, you'll probably need to come up with the application rate/math on your own as the label instructions are geared toward large-scale applications on turf. (I do have some watering can instructions for a Teracure soil drench saved somewhere if you should need them.) They are friendly enough when I've called, but just keep in mind most of their customers seem to be golf course mgrs and experienced large-scale commercial growers so that is who they are used to working with when it comes to questions and advice. For ~200 plants, I go though about a gallon/month when plants are in, if that helps.

Dragonfire is a similar product as mentioned before. Teracure is sesame oil + molasses + emulsifier, and it costs less. I'm guessing this is because the concentration of sesame oil is lower. The goal with either of these products is to have it in the root zone at all times when temps are 65F or above. This is how they work:

http://www.poulengerusa.com/Dragonfi...ppflyerNEW.pdf

Also, I've been told by Poulenger that you do not want to let either of these products dry on the foliage and if any gets on the foliage it should be immediately rinsed off. So when applying, it should be a soil drench or run through a fertigation tank as opposed to overhead spraying for tomato plants.

Dried molasses - I can easily find 40 or 50 lb bags at most better nurseries in my area, and for about 200 plants, I put down an entire bag along with various other soil amendments before planting. Table sugar can be used as an alternative if you just have a few plants. A rough explanation is that molasses (or sugar) feeds the microorganisms that are hostile to nematodes and that's why it can help. It's also a good all-round soil amendment.

Since you won't be able to find a Teracure label online, I've attached a photo. A Dragonfire label can be found here:

http://www.poulengerusa.com/Dragonfi...ecpp_label.htm

[Elizabeth]

Good to know about the chitin. I'll back burner that idea for now.

Thanks for the label - I will give them a call about the Teracure. I wouldn't mind the price on the Dragonfire so much if I felt it would last for a while, but I'm afraid that because it is an oil it might go rancid on me before I got it used (I have a much smaller area to treat than you). The Teracure is appealing since I know lecithin can act as a preservative as well as emulsifier - I would feel better shelling out the cash since I would be more likely be able to use it up before it went south.

I will check my nursery for molasses when I take my soil sample in. I want to find out which species of RKN I have - I was seeing conflicting info on watermelon and corn susceptibility, and I discovered why - they're resistant to some species of RKN and susceptible to others. Erg. Whichever I have likes squash too - I found another 2 beds today that had it - I figured it was the powdery mildew that was doing the butternut and Marina de Chiogga in, I guess I was wrong. I found it quite heartening that I managed to get 11 Baby Butternut squash harvested off the 2 vines today even with RKN. I don't know what's up with the darn MdC - even with hand pollination (I have some little flies that are eating up all the squash pollen they can find so I was giving a helping hand) the plant keeps pinching them off at about softball size. Could that be a RKN thing, or just iffy pollination?

I really appreciate all your help!

[b54red]

Elizabeth I used to have a terrible time with nematodes. I read somewhere long ago that applying large quantities of horse manure would lessen the problem. I tried it and it was fairly effective and added a lot of organic matter to my beds. I have also used molasses and sugar and have found they are both somewhat effective. Another thing that seems to work is planting Nemagone marigolds between the plants but they do take over a bed and make a huge mess by fall. You can also plant hot pepper plants next to each tomato plant and that is also somewhat effective.

I used to have nematodes on the roots of every single tomato plant in my garden; but after using all of the above techniques for years I rarely ever have any signs of nematodes anymore.

[JackE]

Soils rich in organic matter do not have nematode problems - it inhibits their ability to move around. All you need is plenty of compost, added as needed. Unfortunately, in sandy, southern soils like our's where RKN is the #1 pest problem, it's impossibly expensive to maintain effective levels of organic matter. When populations reduce yields beyond an acceptable point, we have to clean-fallow the land for two-years, with frequent plowing, tilling and/or discing.

All of the non-toxic nematicides on the market require high levels of organic matter to be effective. In smaller test patches, we have found that compost/manure alone works as well with or without the nematicide. No need to buy any of those products if you add plenty of compost. Unfortunately, our soil leaches-out amendments as fast as we add them - but for a small scale garden, reagrdless of soil type, I can assure you that organic matter alone will adequately control your RKN - IF you us plenty of it! Research and my own experience suggests that the natural RKN controls are pretty much a waste of money. I won't name products, but we have tried several.

There is a new product from Certus USA that utilizes a live nematode-eating fungi that looks promising and also a lot of GMO research on more resistant cultivars to replace the now-banned fumigants.

I have been fighting them for fifty years plus and have tried every new gimmick that came-out - solarization under plastic, marigolds, brassicas, other trap crops, many chemicals both organic and toxic, etc etc. Bottom line: only three things actually work (1) large amounts of compost (manure, molasses etc), (2) Dangerously toxic fumigants like Vapam (not a viable option for most of us) or (3) starve them out with clean-fallow, tilling frequently for weed control (they feed on weds too) - or even better, deep plowing - with regular crop rotations. Some people fallow with herbicide, but that's less effective because the soil needs to be disturbed regularly to keep exposing it to the sun. This can take up to two years, but one hot summer of fallow will help a lot.

For the small home garden - compost, compost compost! Remember that "N" tomatoes lose all their resistance when soil temps reach 85 or so - and successive generations of RKN will overcome it!

Jack

[carolyn137]

Just adding a few comments.

Jack noted that adding lots of organic matter helps, and it does b/c RKN's move from sand grain to sand grain via the watershell around each grain so the farther apart the grains are the less opportunity for RKN's to build up to destructive populations.

I have several TX friends who have tried the shrimp shell bit with no improvement. Ebon rye has been mentioned and two folks in CA have tried that with no luck, and it also takes the garden out of production for a season since that rye has to be grown then turned under.

About marigolds. Stokes introduced the Neemagon one which is slightly nemocidal as well as being a trap crop. But it's been shown that planting the Tagetes type marigolds, it doesn't have to be Neemagin specifically, doesn't work if planting them just casually, you have to plant the whole area and then till under which again takes the gardening area out of production for a season.

I've been posting online about gardening, tomatoes in particular, since the mid-80's and for those who live in areas where RKN's are a problem it's been a really sad story thru the years and many have had to go to continaer gardening.

N tolerant varieties, are just that, tolerant, not resistant, and that's fine for many commercial farmers who sometimes just need a week or more to get the Brix level up for harvesting, but not so much of a help to the home gardener.

[JackE]

Thanks, Dr. Carolyn

I forgot to mention the elbon rye - I've been there too, with limited results! Every time I heard about something new, I got all excited and enthusiastic, only to be disapppointed. With our current drought/heat situation down here, though, I fully expect nematodes to be much less of a problem for several years at least. They have to be suffering mightily out in that blistering hot, bone-dry sand - and I have no compassion after all the misery they have caused me for so many years! LOL

Jack

PS - I always knew that nems don't thrive in organic matter, but you are the one who told me WHY. Thanks.

[Elizabeth]

Whew - lots of good info! Thanks everyone! I am starting to get an idea of how to go with this. I have spent many, many hours the last couple of days researching nematodes, and your input has helped a bunch. After reading many sites I now have a new 3 ring binder full of printouts from the best of them with highlighting and red underlines plus a bunch of bookmarked sites and computer saved documents - I'm a bit compulsive that way - I like things all organized. LOL

I find it really interesting that what works well for some won't work for others. I have come to realize that getting the species I have identified is critical. From my research it looks like the success of specific suppressive crops and methods can really depend on which one(s) you have. Most information out there seems to refer to them all as a group, or perhaps they are only referring to their most prevalent local kind, and I found only a few sites that really break it down by RKN species. The Alabama Cooperative Extension System papers on RKN were quite useful in that. Sesame has only been shown (says ACES) to work on one species - it isn't clear if the other species were included in the study. Specific marigolds have only been shown to work on certain RKN species, but it's a bit confusing. In an Alabama paper they say that the "'Petite Harmony', 'Petite Gold', and 'Goldie' supported some root-knot reproduction." while a paper from Arkansas says those varieties lowered the populations. A Florida paper says Petite Harmony is susceptible to nematodes and Goldie is resistant. Weeeellllll, shoot! The University of Florida paper goes into great detail on varieties and which of 3 of the common RKN varieties it will work on. If you have M. hapla though, you are out of luck - Florida (not surprisingly) doesn't include the Northern species in the listing. It's no wonder gardeners can't get a consensus on their effectiveness. Similar findings on other cover crops - they work or not depending on which Knot you have, and there is some contradictory stuff on others too - generally because they are talking about different species of RKN. It looks like if you use them on the wrong species, or even with the wrong timing, you could make it worse. Spiffy.

Since these guys love warmth I would imagine climate makes a huge difference in results as well. I'm a couple miles from the ocean. While it's warm enough to plant out frost sensitive things mid March it may not get summery warm here until July (tip: don't ever plan a Summer beach vacation to San Diego in May or June - you may never see the sun). We don't get above 80 degrees very often - mid 70's is a normal summer day, and mid-60's overnight. That's a vastly different climate than most parts of the country, and even the bulk of California.

You have all given me so much good info, and I have formulated my plan of attack:

Find out which species of RKN I have.

I thought I was adding enough organic material each year, but starting now, I will be adding more. This is clearly the #1 most important thing.

More manure - b54red, I wish I could get horse like I used to when I lived in the country, but I'm in the city now and it's tough to find. Gone are the days when I had friends with horses that would even help me load it like they wanted to get rid of it or something LOL

Better irrigation practices - I have been hand watering this year (usually no rain here May - Oct) as the electric on the irrigation system is on the fritz. Time to get the electrician out so things get watered properly to avoid water stress.

Set up a strict crop rotation plan, including fallow (with appropriate cover crop to see how that works for me). I found a great sample plan that includes successions and intercropping from the Texas Ag Extension. I'll mix that up with the one recommended by California, and work out a four year whole garden plan.

Totally clean beds after each crop - no more leaving root bits in the soil to decompose on their own, and no more leaving decrepit plants in to see if I can squeak more harvest out of them.

Temporarily suspend composting garden material. Not all beds are impacted, but some might be and they just aren't showing up because it's a mildly affected crop. I don't want to add materials to the compost that might be infected. Will start later by only composting plant parts that have never touched soil. If I can't add below ground stuff and can't add stuff with Powdery Mildew I don't have much I can compost at the end of summer anyway.

Clean tools when moving from bed to bed (How annoying!)

Dry Molasses - my local nurseries don't have it but I found it online. My local hydroponics store has the liquid version in great big bottles - would that be useful, or does it have to be dry? How much would I use?

Solarization is not an option since I'm too close to the coast - skip that.

Depending on my species I will give the Teracure a try.
JackE, That product looks interesting...OMRI and everything. Since it has such a short shelf life I don't think it will be appearing on nursery shelves soon, but it's promising.

Pay more attention to plants as they are pulled. Since I have been dealing with back issues for the last few years hubbie has been doing the end of season clean out when I managed to get a few things in - a girl has to have fresh tomatoes! He's a sweetie, but a gardener he is not. It's possible he can tell the difference between a dandelion and a carrot, but I wouldn't want to put money on it. It may be that I have had this for a few years and didn't realize it. Here by the coast Powdery Mildew is a real problem, and we're used to it killing off plants by the end of the season. I bet this has been building up and I thought the die off was from PM, and never realized the real cause until I pulled those tomatoes myself this week.

Plant tomatoes (and all Solanaceae) in containers this Fall and next Spring. Give the main garden a year off from tomatoes, even the beds I think are ok. I've been pretty irresponsible - I have had either tomatoes or peppers or potatoes in nearly all of the beds all at once, and with them in all beds there can't be rotation.

Include some N resistant tomato hybrids when tomatoes go back in the garden after some rotation gets the population down...sigh...they are all boring and perfect and red. No lumpy purples or streaked yellows or bi-colors or nuthin'. I think I will continue putting the heirlooms in containers for the foreseeable future to be on the safe side.

Start all my own seedlings - no more vegetable nursery stock. Since these are self contained beds with no yard soil this undoubtedly came in on a transplant.

If I left anything important out, let me know

I've been gambling with possible pest problems, and I lost. I knew better. I knew I should have been doing crop rotation, especially for tomatoes, but since I kept finding new ones to try I kept filling up the beds with them. I blew it and now it's time to pay the piper.

[carolyn137]

Elizabeth, you asked above about species. There are only four species of RKN's known. M. hapla is the so called Northern RKN and there are no tolerant varieties known, so we can eliminate that one ASAP. In all the years I've been posting about tomatoes I know of only ONE documented ID of hapla and that was in MI.

There are three species of Southern Root Knot Nemtodes, incogonita,javanica and arenaria. And at least 4 races are known.

What you have where you are is Southern Root Knot Nematodes and far and away the most common species is M. incognita, according to my tomato pathology monograph.

But they make no distinction between symptoms of the southern RKN's and while I've never researched the N tolerant gene source, it would appear that the tolerance is against all three of the species.

That being said, I don't see that there would be any great difference in using the Tagetes marigolds, the specific cultivars you mentioned above, if that's one route you're pursuing. However dense planting is the rule and letting them grow for the whole season and then turning them under does take the gardening area out of use for the whole season.

You can try that if you want to or any of the other suggestions folks have made such as the products that Suze mentioned that have worked well for her or continually adding more and more organic matter as Jack and others suggested to limit the spread and multiplication of them.

You're fighting the same fight that many before you and many now are fighting when it comes to RKN's so take solace in knowing you aren't alone if that helps just a bit.

[salix]

Elizabeth, you are totally organized with your information, strategy and weapons of RKN warfare - I suspect your results should be written up in the next scientific monograph. Seriously, please post an annual update with results. Good luck!

[feldon30]

Elizabeth,

Most of the info out there about fighting Root Knot Nematodes is tailored to commercial growers. Suze's posts are some of the few personal experiences I've read that address it at a home gardener level. Technical reports and white papers are fine and good, but personal experience is invaluable.

[Elizabeth]

I'm taking the same approach to this as I take to trying new tomato varieties - try whatever I think might work for me, keep that which is good, toss that which is not. Now, come to think of it, I've been tossing quite a few heirlooms the last few years thinking they were way too low in production to warrant a future garden slot, I may have mis-judged them. The poor babies may have just been sick and I was a bad mom.

I'm not sure if cover crops and the other stuff will help, but if I don't give them a trial it will niggle at me. I know nothing is a magic bullet, and frankly, some may be too much of a pain in the hinney (like turning under the cover crops), but I won't know what will help my garden unless I try. My goal is to keep the population down so I can get food out of at least part of my garden year round, and with the heirloom toms in containers I will have a lot more wiggle room and can afford leave a few beds fallow each season. Oh that will be hard...purposely leaving beds empty of vegetables!

It's funny that with all the things I'm looking at having to do here the thing that irks me the most is that I have to wash my tools and hands between beds to delay the infection moving as long as I can. At least they are raised beds so I don't have to wash my feet. LOL

A few days ago I was really in despair - I always knew this nasty bugaboo was hiding out there in the big bad world, but had always managed to avoid it (dumb luck probably) in my own yard. I thought it was the kiss of death for my vegetable beds. It has been really helpful to hear the voices of experience and know that it's not the end of my vegetable garden as I know it.