Battling Rootknot Nematodes

[Goodloe]

From GoDawgs above: "Totally nematoded". That would be a great screen name here on TV! It is very descriptive and very versatile...

Dang, my sinuses are really acting up; I feel just totally nematoded....

Whew, work was a booger today! I am wiped out...totally nematoded....

Ugh...shouldn't have drank that whole 6pack last night; I feel like compost. Totally nematoded....

Good on you, Ms Dawgs, great term!

[GoDawgs]

Originally Posted by Goodloe

From GoDawgs above: "Totally nematoded"... It is very descriptive and very versatile... Good on you, Ms Dawgs, great term!

Aw, shucks... maybe we can shorten it... "totally 'toded"

[Goodloe]

Originally Posted by GoDawgs

Aw, shucks... maybe we can shorten it... "totally 'toded"

Even better!

[rick9748]

Nice job and thanks.Located in zone 8 central part of South Carolina.In boat with you constantly fighting rn nematodes.Tried Monterey Nematode Control and did see improvements.Love my Cherokee Purples and you know they are resistant to nothing.

[rick9748]

Used Monterey Nematode Control this year on 8 Cherokee P & 4 Mortgage L and this product appears to have reduced the nematodes by 70% as compared to other plants.
It is expensive but appears to have helped.
Would like to hear feedback from anyone that has tried the product.
Thanks
Rick

[rick9748]

Any comments on shrimp/crab meal {chitin} ?
Have you used, how used any help on the nematodes??

[rick9748]

Raised beds have to have 3/4 in. of soil removed to allow room for new compost and cover crop to be worked in??Have never heard this discussed before and just wanted some feed back.
Thanks
Rick

[eyegrotom]

I don't have any problems with nematodes but I routinely remove a couple of inches of soil from my raised beds and replace it with new compost soil mix

[GoDawgs]

Today I decided to dig up the two 'Stewart's Zeebest' okra plants I tried this year. They were decidedly different okras, but I digress. This was, at least last year, a bed whose plants showed no evidence of nematodes. Not this year. Okra roots:



This surprises me as they were pretty prolific plants all season. There are still two 'Bowling Red' out there that I tried this year along with three 'Jing Orange', which has been my go-to okra. All five have dropped most of their leaves and slowed down production but it's about time. It will be interesting to see the roots once I pull them.

On the other hand, I noticed that all of the Jing are pushing new foliage at the main leaf axils so I will hold off removing the plants. Instead I will let the plants make more pods and let them dry for collection.

[Goodloe]

wow, Miss Dawgs, you got toded again? It's amazing to me that the critters attack almost anything... Good luck, and keep us posted! ...and Go Dawgs!

[GoDawgs]

I had a revelation the other night. Perhaps it was the wine. Rather than take chances with the nematodes, just plant on that side of the garden the stuff that they don't bother. Duh. So for the next season that means the garlic, onions, scallions and anything else planted real early while the soil is still too cold for the 'todes to want to get out of bed. That would include the green peas and the real early brassicas like cabbage that I'm now planting out early February (pushing the envelope!). Also the early Spring Treat corn I'll try in a bed. It's technically a grass and 'todes won't mess with it at all.

It almost seems that if plants can get up and running and get some age to them before the attack begins, they do better. But that doesn't explain the successful okra which was planted in warm soil unless the population just started to build in that bed late summer.

It also means I'll have to shoehorn everything else into the other side of the garden. I'll have to ponder on that. Maybe over another glass of wine.

[b54red]

Dawg, I get nematodes nearly everywhere I plant okra before the season is over. Two things that seem to help a lot are keeping them mulched and watering them regularly and heavily. Before I started doing this I would lose most of my okra plants just as they started to make good. Now almost all of them last til I am sick of okra or it is too cold and all the leaves fall off.

When I pulled my cantaloupe this year they were eaten up with nematodes. Some of them had it so bad that the ground right under the main stem was just a solid mass of nodules. It was like digging up a big rock under the plant it was so solid. I have seen a lot of nematode damage over the years but nothing close to what I saw under the cantaloupes. Surprisingly they made really good up until late July then faded fast.

Bill

[GoDawgs]

Thanks for those insights, Bill. These okra were mulched and watered well. Lord knows that okra wants all the heat it can get and all the water you can pour to it.

That's amazing about your cantaloupes. I've never seen neemies that bad and never hope to!

[b54red]

Originally Posted by GoDawgs

Thanks for those insights, Bill. These okra were mulched and watered well. Lord knows that okra wants all the heat it can get and all the water you can pour to it.

That's amazing about your cantaloupes. I've never seen neemies that bad and never hope to!

I'm not going to grow cantaloupes again I don't think. I was astounded at the nematodes and with my soil and location I don't want to grow anything that encourages them. I have been dealing with them for over 40 years in this location and up until the cantaloupes this year they had been getting less and less of a problem. My cantaloupes were very heavily mulched and well watered but it didn't help them like it did my cucumbers and okra in the past so I can only assume they are much more desirable to the nematodes.

Bill

[GoDawgs]

I did a lot of researching on Sunday, trying to chase down that small reference I came across about using molasses against nematodes. It's all in how you phrase your search I guess. Some things I found about molasses and other things:

MOLASSES

1. Molasses can be used to stimulate soil microbe activity aiding nutrient uptake, deal with certain fungi and soft bodied insects and stimulate compost pile breakdown. There are "reports" that molasses can drive away nematodes and fire ants (THAT I'd have to see to believe!). See:
https://fifthseasongardening.com/mol...-hyde-to-pests

2. This article talks about molasses, gives an application rate of 2 TBS per liter of water but offers a caution. "Molasses works by increasing the food source for bacteria in the soil. It changes the balance of bacteria/fungi/nematodes in the soil biology, and this may not necessarily be a good thing. Earthworms can be adversely affected also. Use this treatment sparingly and as a last resort." I also read several other places that that statement is nonsense. See:
https://www.greenlifesoil.com.au/sus...tips/nematodes

One other interesting item in the above greenlife article is that most brassicas, not just mustard, deter nematodes. A different article suggested tilling in brassica refuse (cut leaves, etc) for the same purpose.

3. Molasses was effectively applied against nematodes in papaya, onion and Chinese cabbage trials. Paper from the Hawaii Ag Research Center:
https://www.hawaiiag.org/harc/VEG3.pdf


4. The use of molasses to boost soil microbial activity does have some caveats which this next article explains. It also discusses types of molasses, application, use in compost tea etc and ends with some points to ponder from a Dr. Elaine Ingham:
http://www.thesoilguy.com/SG/Molasses

CORN

1. I had read in many articles that corn is not susceptible to RKN because it's a grass. But I found another article stating that after the 70's, hybrid corns became susceptible: "Unfortunately, all corn hybrids on the market today apparently are good hosts for Southern root-knot nematodes and will maintain, if not increase, their populations rather than suppress them, according to researchers. It is believed that resistance to this particular species of nematode was lost over the years because plant breeders failed to screen corn breeding lines against it."
https://www.farmprogress.com/root-kn...s-problem-corn

I had a grown a field corn in an RKN affected raised bed two years ago, testing the bed method and the RKN resistance thing. It grew wonderfully. After reading the above I think it may have been because the corn was an old heirloom, Boone County White. This year I'm growing Spring Treat in that area. It's a hybrid so we'll see.

2. However, a different article from Virginia Extension says corn, although not infected, serves as a host and boosts existing RKN populations so that succeeding crops are really affected. Heavy sigh... I'll plant the Spring Treat anyway and maybe try molasses as a light soil drench. This variety germinates in cool soils so maybe it will get a jump on the RKN population.
https://pubs.ext.vt.edu/444/444-107/444-107.html

ROTATION, TIMING

A publication from NC State confirms my thoughts about planting cool season stuff in infected areas and again in late fall. It also gives a useful list of specific resistant vegetable varieties. My Wando peas are on the list. They did just fine in the RKN area last spring and when pulled up May 20 showed no sign of RKN on the roots. See:
https://content.ces.ncsu.edu/control...getable-garden

The battle continues...

Originally Posted by GoDawgs

Southern Root Knot Nematodes. They invaded my garden about five years ago, coming in (I think) on a truck load of soil I had delivered while building new raised beds. They’ve gradually spread to other beds, probably from a combination of water drainage and hitchhiking on tiller tines, shovels and hoes during the time I didn’t know I had them. And I've been battling them ever since in about two thirds of the sixteen 4'x18' raised beds that make up the veggie garden.

They are microscopic worm-like organisms that invade plant roots, multiply and disrupt the flow of water from roots to upper plant. The result is stunted growth and little plant output. Plants look thirsty but watering doesn’t help too much; maybe just a temporary boost.

You can't kill them and can only hope to knock them back and suppress them with a combination of methods. Here's information on early symptoms I gleaned from some southern Extension Service websites and others:

Above ground symptoms of a root knot nematode infestation include wilting during the hottest part of the day even with adequate soil moisture. Damage is most serious in warm, irrigated, sandy soils. It’s easy to see the loss of vigor, yellowing leaves, and other symptoms similar to a lack of water or nutrients. And, of course, the knotted roots you find at the end when you've watered and watered, fertilized and the plants finally look bad enough that you pull them. Some cucumber roots:




Infested vegetable plants grow more slowly than neighboring, healthy plants, beginning in early to midseason. Plants produce fewer and smaller leaves and fruits, and ones heavily infested early in the season can die.

Things to do for suppression of nematode populations:

Plant nematode resistant veggies/flowers.

Plant as early as possible in spring and as late as possible in fall. I learned that in soil temps below 64, nematodes can’t function so it's best to plant resistant stuff as late in the fall as can be safely done and really early in the spring to get a jump on the nematodes. They don't infect older plants as hard as they do young ones. Because of that, it also pays to grow really large transplants if possible.

Get lots of organic matter into the soil because high water retention in soil helps fight nematode attacks. I mulch with leaves raked in the fall and till them in when the crop’s done.

One extension service suggested tilling the infected beds every ten days in the summer as the hot sun will kill eggs brought to the surface. While doing this, also keep the soil moist to induce egg hatch and keep weeds out so that any newly hatched nematodes have nothing to feed on. Starve ‘em! I did this faithfully the summer of ’16 and it seemed to reduce the ’17 population so I did it again last summer. This spring I’ll see if it helped.

Thickly planting French marigolds and mustard several times in one season and tilling them in disrupts the reproductive cycle and it did help a little. They have to be French marigolds (species Tagetes patula) as some other marigold species can attract more nematodes. I cheated by planting them along just the edges of one bed and although I’ve read where you have to plant the whole bed for it to be effective, what I did seemed to help a bit.

I've read where sowing mustard and then tilling it in several times in one season disrupts the reproductive cycle. It seemed to help a little and mustard seed is really cheap at the feed & seed store. The mustard’s volatile oils knock them back enough that the next year you can plant other stuff before having to repeat the process. Territorial Seed has in their Brassica Cover Crop section a ‘Mighty Mustard’ that has high levels of volatile oil to act as a natural soil fumigant. I haven’t tried it yet.

Plant winter cover crops (annual rye, rye or wheat) after several fall tillings. I sowed annual rye in four fallow beds this past fall and just now turned them under. It’s the first time trying that

Plant summer cover crops and till them in. In ‘16 I grew some sorghum in one bed just to starve the critters. No more of that as it was a mildew and aphid magnet. Late last spring I planted two beds with Sunn hemp which is supposed to have a somewhat nematocidal effect when chopped up and tilled in. We’ll see this year if it had any effect.

Good garden sanitation practices. Thoroughly clean all tools used in infected areas.

Since I have something growing in the garden all year long I have to pick and choose my battles. Beds that show big nematode damage get targeted for war. There hasn’t been any damage in the fall planted veggies due to the colder weather. I’ve read where RKN don’t bother corn, onions. So far that’s true.

There’s currently some research going on exploring the use of molasses, of all things, against nematodes. Something about a diluted spray. If I find any more about that I’ll post it. It's WAR, I tell ya!

Resources (in no particular order):

http://www.missouribotanicalgarden.o...nematodes.aspx

RNK in garlic: http://www.gourmetgarlicgardens.com/...es--pests.html

http://www.clemson.edu/extension/hgi.../hgic2216.html

https://content.ces.ncsu.edu/control...getable-garden

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7489.html

There’s also one I had from U. Of Florida but I can’t find it right now.