Root Knot Nematodes

eltejanoJune 17, 2010

Nematodes broke-through the m1 gene in our resistant tomatoes this year. Also, soil temps got into the 80's well before harvest, thereby rendering the resistant gene ineffective. The tomato plots, which are drip irrigated and comprise 35 thousand sq ft, are so severely infested that we are either going to have to fumigate this fall or take that area out of production and clean fallow/solarize for several years. (The degree of infestation is beyond crop rotation or trap crop solutions).

Our project technical advisor has limited experience with nematicides like Vydate or Telone and is not comfortable with them. Methyl Bromide is no longer legal and Vapam is very expensive, difficult to obtain, dangerous to apply and often ineffective. The bottom line is that we simply don't have the expertise to safely work with these highly toxic chemicals.

According to the experts at TX A&M. LSU and U of Florida and our own review of the literature, there are no really effective organic nematicides that would work - especially in our coarse, sandy soil which has little organic matter. Solarization and clean fallow for several years appears to be our only solution.

Since nematodes are inactive at soil temps below 70 degrees, we are considering the following strategy as an

alternative and would welcome any comments:

(1) Remove and burn all tomato plants from infected areas when harvest ends in a few weeks. (2) Till deeply and clean fallow with glyphosate and/or solarize under plastic the rest of the summer. (3)When the soil temp drops below 70 in the fall and the nems are inactive, plant our winter greens in those areas and harvest them through spring until soil temps reach 70 again. (4) Till-in the crop residues and again clean fallow the infected plots all summer until fall. (5) Plant our tomatoes elsewhere and repeat this brassica/fallow rotation for several years until soil tests show that the RKN population has declined sufficiently.

We understand that brassica residues also help suppress RKN activity to some extent. If they have nothing to eat during their active months, we should starve them out...???

Thanking you in advance for your comments. We are a church-affiliated grower providing fresh vegetables to the public at no charge. We do accept donations from those who wish to contribute.

Jack Ellis

Gardeners for Jesus Ministry

Woodville, Texas

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budb(8b)

Jack
Frequent deep tillage can be effective if you have the
equipment and the horsepower. Try plowing under a thick
stand of Florida Broadleaf Mustard, 8 to 10 pounds
per acre, and till in as deep as you can when mustard is
about 6 inches tall. You probably have enough time to do
this two to three times this summer/fall and still get a
fall/winter crop in.
Solarization is a wasted effort. You can't get the soil
hot enough deep enough to have even minimal effect.
Try the mustard and deep tillage route. The worst that can
happen is an increase in your organic matter.

Good Luck!
Bud

    Bookmark   June 17, 2010 at 2:33PM
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eltejano

Hi Bud!

Thanks for the info. Despite spotty nematode damage, we're having a pretty good tomato harvest this year. We picked 600 pounds of Amelias yesterday and it's just getting started. We're running a double shift 6 days a week at the stand right now and we're raising some serious money for the youth mission trip. If we can't fumigate, though, the RKN will be devastating in that area next year.

Finally got the Florida Weave down pat. LOL I don't think I'm doing it like you (I don't carry a box of twine on my belt). You're probably faster, but it works - as you know, Amelia is a big plant with a heavy fruit load, and the three runs of baling twine and 3/8 rebar every two plants are supporting them okay.

We're still trying to get the technical and logistical support we need to fumigate the area - that's the only sure way to deal with it. Yesterday,at long last, we finally established a connection with someone at Dow Agroscience. Hopefully, Telone will be an option for us and, if so, they will provide the tech assistance we need to safely apply it. Bye, bye nematodes! (for a couple years LOL)

Jack

    Bookmark   June 19, 2010 at 6:20AM
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softmentor(z9/sunset13 CA desert)

consider another possibility. Use a DEEP mulch, 12 inches. This insulates the soil so the temp doesn't get as hot. Be sure to run your drip only when the sun is down, and wait an hour after dark before starting. You don't want the sun making the water hot and thus warming the soil.
I have had very good success with planting of other crops (not tomatoes) and keeping the water cool by running drip only in the cool hours after the sun is down is a big help.
Another benefit of mulch is it will help support other factors, both physical and biological, that work to inhibit nemas. Use a permanent mulch, don't turn it under, and let the soil build a good and proper soil structure of O, A, B, and C horizons.

    Bookmark   July 18, 2010 at 11:45PM
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