root knot nematodes

Belleair, FL(Zone 10a)

So I've been having issues with my squash plants & pulled 1. I found the roots looking all lumpy. They look identical to the pictures online of root knot nematodes. The only solution I've found so far is to move the garden or try to find crops they don't like. Any ideas?

Thumbnail by brownthumb78 Thumbnail by brownthumb78 Thumbnail by brownthumb78
Charlotte, NC(Zone 7b)

I used to live in south Florida. Root knot nematodes are very bad there.

I found that lots and lots of organic matter spread across the top of the old layer of soil helped somewhat. Try not to mix the old soil with the organic layer. Õ repeated this once a year.

Then put in transplants, and get them to produce fruit as fast as possible. I never did have any luck growing melons or cucumbers, but that was because of powdery mildew!

Belleair, FL(Zone 10a)

I pulled some less productive plants from different spots in my garden & the problem (at least right now) seems to be limited to a 3'x3' area. Do you think putting the organic matter on this area then covering with plastic to solarize it would be my best bet since there arent any pesticides or whatever to get rid of them?? My garden is small to begin with & I hate to lose the space but I feel like I'm running a halfway house for wayward insects & just want them to go.

Charlotte, NC(Zone 7b)

brownthumb - if you want to solarize - put the plastic on the
old soil. If I remember correctly, nematodes don't move through
the soil very quickly, so try to kill them before they move up into
your new top layer.

Belleair, FL(Zone 10a)

OK. Thank u!

Contra Costa County, CA(Zone 9b)

Yes, solarize. It may have to be repeated every few years. Perhaps practice a 5 year rotation of your crops that includes solarizing each bed once, then planting a different plant family in each of the four years.
ie:
Solarize
Cucurbit
Legume
Corn/Greens
Solanum
Herbs/Onion

Do not cross-contaminate the known trouble area with areas presumed to be nematode free.

SW, AR(Zone 8a)

My aunt and uncleís garden had them. Thatís what they said it was, anyway. Their gardenís production went precipitously downhill over a couple of years, I know. They let the plot lie fallow for a while, moved gardening to another area, entirely. I canít recall for exactly how many years, maybe three or four. They allowed nothing to grow on the original garden spot, kept it disked up. Then they moved back to the original spot; it was closer to the backdoor. Problem, whatever it was, solved. Starved Ďem out, I guess.

Delhi, LA

I read somewhere that planting marigolds along your veggies keep the nematodes down.

Adding the compost works. I had nematodes on one end of one of my raised beds last year. I add compost every year but doubled up and everything produced well. Guess I'll find out if they are still around when I start pulling stuff up.

Crazy thing in my garden this year. Borers killed all my American type cucumbers but didn't touch the Japanese ones.

Charlotte, NC(Zone 7b)

Adam - your suggestion of letting the area go fallow for a few years is a great one.

brownthumb - the important thing to remember if you use Adam's suggestion, is to NOT let ANYTHING grow in that area.

Jim - I seem to remember that it's French Marigolds that deter nematodes. I don't think other marigolds work against them.

Charlotte, NC(Zone 7b)

Here's a hint to avoid bringing nematodes into your garden.

Don't bring plants from a neighbor's garden into your own.
Sounds ungrateful, but it's the best way to avoid bringing
these pests into your garden.

Plants from nurseries should be okay because they don't,
or at least shouldn't, use regular garden soil.

Belleair, FL(Zone 10a)

What about plants from like home depot, Walmart, Lowes etc?

Charlotte, NC(Zone 7b)

brownthumb - I would be cautious with shrubs and trees to be sure they had not been grown in the ground before being transferred to a pot.

Plants that were seeded or transferred from grow-benches into pots should be fine as these are grown in some kind of potting mix, not regular garden soil.

There probably are regulations in place that plant nurseries have to abide by so that bugs do not move around the country. Having said that, I've seen live bugs on plants in nurseries, so it's always best to err on the side of caution.

Belleair, FL(Zone 10a)

OK. Thanks honeybee!

Moorpark, CA

I have to say, I believe I got both root knot nematodes and fusarium wilt from plants grown in nurseries. I've read about these problems extensively, and it is a problem. Nurseries do pass these things on. I will never buy another heirloom tomato seedling, because they are susceptible to fusarium and they carry it. It may be harder to control than root knot.

Also, growing cover crops using some plants that attack and kill root knot (with compounds they release when you cut and till them under) and others that trap them are better than growing nothing in the soil while you keep the susceptible plants out.

Specifically, French marigolds - Tangerine (Tagetes patula) are the ones that kill several varieties with their pyrethrin content. You have to be careful because some marigolds (like signet) either don't work or make the problem worse. Root knot nematodes feed and reproduce on signets.

You have to grow the marigolds as a solid planting. They don't work well when interspersed with other plants. Cut them down and turn them under the soil before the flowers open to avoid getting the seeds in your soil (verify this to understand when they seed).

There are a lot of recommendations for cover crops that suppress the root knot. I am trying Cahaba White Vetch this fall and Tangerine French marigolds in the spring as a double whammy.


South Florida, FL(Zone 10b)

I live in South Florida, the root knot nematodes are really bad down here. If you don't do anything about them they will totally destroy your garden, because it is always hot enough down here for them to thrive.

First thing is you can never add enough organic matter, it helps. But unfortunately nothing you can do will totally put a stop to them right away. For some reason there are no actual chemical or organic products that will kill them. (At least I haven't found any yet, and I've been looking for years).

According to the University of Florida, there have been studies that show "planting a cover crop of cereal rye (Elbon) in the fall to grow during the winter will decrease nematode populations." Unfortunately, cereal rye likes cooler weather and in zone 10, winter is the only time most veggies will grow. I bought some seed and I am going to try either seeing if it will grow at all during our summer or I will have to try and do half and half during the winter. My gardening area isn't very big, so crop rotation isn't exactly an option. Apparently rye is something you have to do before each veggie planting season for it to keep numbers down.

Marigolds need to be planted in mass for that to keep numbers down at all. It's not really french vs African marigold, but certain marigold work better for certain nematodes. Like down here a big problem is the southern root knot nematode. One of the marigolds that work best for them are the "crackerjack" African marigolds. But other types of "bad" nematodes can actually breed on crackerjack. Same goes for pretty much every marigold, there is no marigold that works against all bad nematodes. Also according to UF, interplanting marigolds among your veggies has no positive effects.

South Florida, FL(Zone 10b)

So..... if you are like me it is a constant battle and it seems like there is actually no good control. :-(

Glendale, UT(Zone 5a)

beneficial nematodes, eat root knot nematodes, - Gulf Coast biological, - or Arbico.. works great for me...

Lynnwood, WA

Solarizing is pretty effective, you could also amend the soil with neem meal as well as diatomaceous earth

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