The Ugly Bumps

I grow a lot of food here, as you know, and I have no problem showing off my bounty, yet if that is all I do, I am lying. Failures and struggles happen here at the ranchito, too. This summer, I've begun a battle against a bitch of a soil pest: the root-knot nematode. Luckily, most of my favorite fruit trees are on Nemaguard rootstock, which helps them withstand both the bugs and the droughty nature of our climate. The tomatoes, though, they suffer. I planted ten plants this year and harvested approximately the same number of pounds. Harrumph.

Though I knew nematodes were my problem, I didn't know what to do about them. I had tried this spring to use beneficial nematodes to help counter the root-knot nematodes, but that turned out to be an expensive yet value-less investment. I went then to wise members of my local produce exchange—a font of local gardening knowledge—and the Internet for solutions, and I've learned, as is often the case with a difficult problem, there is no silver bullet. Instead, I'll have to incorporate additional strategies into the crop rotation, compost and manure amendment, and liquid seaweed fertilizer that are already my practice.

How I know I have root-knot nematodes:
  • Ugly bumps. Last year, when I pulled out my tomatoes and a few other plants, I could see the heavily galled, deeply scarred roots. These weren't smooth main roots with lots of healthy, happy feeder roots, but instead a medusa-head of succulent-jointed ropes. I hung my hopes too heavily on what I thought a winter free of food would do to the root-knot communities. They, persistent suckers as they are, made it through the winter quite happily to hit this year's crop even harder.

  • Weak plants. My tomatoes, squash, and melons really struggled this summer. They'd wilt after only a single day without water, when usually they'd need water only twice a week. If I looked at them wrong, they'd get sick. Most of the flowers on my tomatoes just fell off rather than setting fruit, and the majority of my squash and melons aborted fertilized fruit because they just didn't have the means to support the fruit to maturity. Beans, sweet potatoes, tomatillos, and peppers seem to be able to tolerate the nematodes better than tomatoes and cucurbits.

What I am doing as I clean out the beds now and into the future:
  • Amend with more horse manure than ever. This will provide as rich as possible a medium to support struggling plants. As well, it will add more organic material to help ensure water retention, a deep challenge in our soil.
  • Seed a winter cover crop of rye and mustard. I'll do this in half of my beds, those that will host next year's tomatoes and melons, come mid autumn. Root-knot nematodes are unlikely to feed on rye roots (apparently rye doesn't appeal to those buggers), so the plants will grow heartily over the winter, pulling up nutrients with their extensive root systems. While the nematodes may nibble on the mustard roots, the mustard will have its vengeance in the spring when I cut both the rye and mustard down and dig the plants into the soil. The mustard will gas the nematodes, and the rye will decompose quickly and feed the surface soil with the nutrients it pulled up from the deep.
  • Add dried molasses to the soil. With every plant I plant, this fall, this winter, and next spring I'll be adding dried molasses. The molasses helps feed the microbes that both attack the nematodes and work symbiotically with the plants' root systems. This may be something I need to do forever.
  • Plant French marigolds. Tagetes patula, when attacked by nematodes, interrupts their reproduction. I plant to start loads of French marigolds in the early spring so I can plant them thickly among my tomatoes and melons next year.

What I could but won't do:
  • Solarize with black plastic. Yes, this would kill my mean root-knot nematodes, but it would also kill my lovely worms, happy microbes, red spiders, and other good guys.
  • Mulch heavily in the vegetable garden. I'm a huge proponent of mulch in most places, but in my vegetable garden, I've found it makes it impossible to direct seed beans or squash or okra, or any of those other delicious vegetables that grow best when they stay where they started. Mulch provides a home for hoards of sowbugs that take out seedlings overnight. (And, don't join the chorus that sings "Sowbugs only eat decomposing matter"; I've watched them munch down a bean seedling. Sowbugs and seedlings do not mix. That chorus sings the wrong tune.)


Michelle said…
That is a huge bummer. :(

You might try amending the soil with crab meal also, it's a great slow release natural fertilizer and the chitin in the crab shells is supposed to feed the organisms that break down the chitin in the nematode shells.

Have you ever tried a mycorrhizal innoculant? This year I innoculated some of my pepper plants with an innoculant and those plants grew (are growing) like crazy and even though they were set out out later than the rest of the peppers and received no protection from our cold summer nights they have surpassed the rest of the peppers is size, vigor, and fruit production. It's been pretty amazing to watch. Perhaps a good dose of mycorrhizae would help your tomatoes to get more nutrients and water.

Good luck!
Christina said…
Thanks for the good advice, Michelle. Do you know a reasonably-priced source for crab meal? I've looked around, and everything I've seen is so expensive, so much so I can't rationalize spending it. I did, however, buy some inoculant this summer that I plan to use when planting out fall seedlings.
Anonymous said…
I had this problem last year and it got the better of me -- I've been sulking ever since and planted nothing. But heck, the very least I can do this year is imitate every (easy) thing you do.
Christina said…
AH: If you're going to do one thing from the list, I think a cover crop of mustard appears most effective from my reading. Good luck!
Anonymous said…
Is the rye the same rye seed used to overseed lawns?
Christina said…
AH: The overseeding rye is annual rye, which is supposed to be a good cover crop, too. I'm using cereal rye, aka "winter rye" because my veg beds are in the coldest part of my yard and regularly get frosted over the winter when I want to have a cover crop, so the annual rye would have a tough go of it.
Emily said…
So frustrating.

I suspect that I had this same issue last year as I had the most pathetic issue of tomatoes and squash ever. However, last winter I covered cropped with this mix:

I was impressed with the results. I got a good (not great) tomato harvest this year and I got a few winter squash and a good amount of summer squash. My cucumbers still struggled but I think I may have another issue there. My beans have seemed unaffected either way.

I will say that all of this gives me such a better appreciation of what it takes to grow enough food to feed a family. Every time I have a crop failure I think of reading Laura Ingalls Wilder and of what it must have been like to be totally reliant on your garden/farm.
AJK said…
I'm having issues with Root Knot Nematodes as well. grrrr. Not happy about it at all. It spread from one plant my Mom bought at a nursery. Now it seems like it's going everywhere
Christina said…
AJK: What your battle plans against the nematodes? I'd love to compare notes.
my tomatoes were a total bust except for that topsy turvy contraption I got at the 99 cent store. I have left one plant (dead) in the soil, and I think when I pull it, out I'll be looking for those nasty roots. Just seems I spend tons on tomatoes without much reward - a yearly thing
Mike said…
I found that a winter crop of garlic really helps my tomatoes the next summer. As a plus, I get a full year's supply of garlic. I got this idea after taking out some chinese leek and getting great tomatoes in that pot the next year.

I don't have any root inspections to reference, so I don't know if the problem I am solving is a nematode problem, though. I grow in pots, which might make my results less generalizable.

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