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Root-knot nematodes

 
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If you have ever had a root-knot nematode problem in your soil, you are aware of the devastation they can cause. I was thinking about what causes this problem. To use an analogy, about 50% of the world's human population carries the bacterium Helicobacter pilori in their gut. However, only a small percentage of these individuals experience the paralyzing gastrointestinal problems that it can cause. This is because most of the time it is in a state of balance with other microorganisms in the gut and its population never reaches the level where it can cause problems.

I suspect that something similar is happening with so-called bad soil nematodes like root-knot. The system is out of balance, allowing the root-knot population to surge above normal levels and cause problems.

Does anyone know how this process occurs in the soil and how to restore it back to a balanced system?
 
pollinator
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Location: Big Island, Hawaii (2300' elevation, 60" avg. annual rainfall, temp range 55-80 degrees F)
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I don't know a lot about this subject, but I do happen to have rootknot nematode in my soil. Initially I had significant problems, not just because of the rootknot nematode but because of generally poor, thin soil. I gradually switched to more resistant varieties of veggies to grow, although I still do grow a bit of everything and anything. I discontinue growing varieties that really suffer with this nematode.

Over the past 15 years I've tilled in a lot of compost, manure, and other soil amendments into my gardening areas. I routinely till in a 3" deep layer of homemade compost between each crop. I mulch with fresh grass clippings, and depending upon the crop, use added manures and coffee grounds.  I also use various teas on some crops if they need them.

As a result I can produce a lot of food, irregardless of this nematode. I suspect, though have no proof, that two things contribute to my ability to farm even though the soil has rootknot nematode. 1- I incorporate repeated amounts of fresh, active, high quality compost. 2- I keep the soil moist and mulched.
 
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Location: South Carolina 8a
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Angela Aragon wrote:If you have ever had a root-knot nematode problem in your soil, you are aware of the devastation they can cause. I was thinking about what causes this problem. To use an analogy, about 50% of the world's human population carries the bacterium Helicobacter pilori in their gut. However, only a small percentage of these individuals experience the paralyzing gastrointestinal problems that it can cause. This is because most of the time it is in a state of balance with other microorganisms in the gut and its population never reaches the level where it can cause problems.

I suspect that something similar is happening with so-called bad soil nematodes like root-knot. The system is out of balance, allowing the root-knot population to surge above normal levels and cause problems.

Does anyone know how this process occurs in the soil and how to restore it back to a balanced system?



Root-Knot nematodes are incredibly resilient. They thrive in poor sandy soils, like many in my area; the high hills of Santee, in South Carolina. Farmers put down some really nasty chemicals, which of course only compound the problem for next year. You seem to be on the right track already. Compost teas and carbon inputs are your best friend when dealing with these nematodes. Bryant RedHawk's soil posts are a great start.

PS. Companion planting with marigolds can help as well.
 
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hau Angela,
Root-knot nematodes are plant-parasitic nematodes from the genus Meloidogyne.
They exist in soil in areas with hot climates or short winters.
Root-knot nematode larvae infect plant roots, causing the development of root-knot galls that drain the plant's photosynthate and nutrients.

You are correct in thinking your soil is out of balance, what is missing is enough arbuscular (arbutoid fungi) mycorrhizae inside your roots.
You are probably also lacking ectomycorrhizae (these guys will trap and eat the adult parasitic nematodes) around your root systems.
For a quick way to restore the balance you could purchase a mycorrhizae product to amend your soil, around your plants.
If you can make enough compost with manure layers, the aerated tea you can make from that compost will also add in the arbuscular mycorrhizae and the ectomycorrhizae.

Redhawk
 
Angela Aragon
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Thank you everyone. My small farm is in what 100-150 years ago was a tropical cloud forest in Nicaragua. This land was cleared first for timber, then planted with crops for about 2 years until the soil ecosystem collapsed and it could not support any crops. It finally was converted to pasture, dominated by Bermuda grass, and was overgrazed year after year. This story is repeated over and over in the tropics. It still is occurring in the rainforests in the Atlantic region of Nicaragua (supposedly protected land).

We know that forest floors are fungally dominated. Given what Red Hawk wrote, I suspect that the soil on my farm used to be fungally dominated and lost that balanced ecosystem a long time ago when the tropical cloud forest was cleared. This allowed organisms like root-knot nematode to flourish. Indeed, entire coffee crops are lost to its infestation in this region.

For the past five years, I have been in the process of restoring my 8.5 acres by planting trees and shrubs. There have been numerous setbacks, including major challenges associated with climate change. However, I can look out over the land now and see that things are moving in the right direction.
 
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Hi Angela,

Everyone had good advice that will help, one option that wasn’t mentioned is preditor nematodes. With nematodes being one of the most aboundant family of all species on earth, there is almost a paracitizing nematode for every species or genus on earth, even other nematodes. So depending on the soil environment or season of application, you may be able to use a preditor species of nematode that spacifically targets root-knot nematodes as its host.

The reason this may be only seasonal in application, is that nematodes are almost classified as a semiaquatic paracite, meaning they like to stay moist. So they will need to stay within certian moisture parameters until they target their host. Soil that lacks organic matter or the ability to retain moisture, won't have the ability to sustain the biological diversity that allows balance to be maintained, wheather it's mycorrhizal life, or beneficial paracitizing nematodes; however, while your trying to transition your soil, during the wet season, or with reliable adequate moisture available in the soil, an application of these preditor nematodes may be feasible to help immediately slow the problem.

I know there are species of preditor nematodes sold that spacifically target root-knot nematodes. The question is: will your available conditions be inductive to them performing their duties, and if not at this time, will their be seasonal conditions that may. Then if so, all you need to do is find a reliable source of the preditor nematodes, and make sure they are kept viable in shipping, also making sure you handle them to maintain their viability even in application.

It shouldn't take but a few searches on-line, to get answers to these questions, then find a reliable source if its feasible. The closer the source, the better chances they will stay viable in shipping. In the heat of your area, they may need refrigeration to stay viable , so those are all factors to consider if making a purchase.

Hope that helps!
 
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Just adding a nice, short review on Meloidogyne genus nematodes:  https://www.apsnet.org/edcenter/disandpath/nematode/pdlessons/Pages/RootknotNematode.aspx

As noted in the review and complementing the comments above, there can be genetic resistance, to varying degrees and robustness, in the different crops you are trying to grow.  Maybe something to look into if you have a few favorite crop species that you wish to keep growing in your area.  Good luck!
 
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