Root Knot Nematode (RKN), Heat Treatment, and Root Pruning

15 years ago

To my dismay, my one of my Italian fig trees was found to have RKN. So, I used the heat treament first fostered by James, it can be found at:

http://forums.gardenweb.com/forums/load/fig/msg0101273530670.html

Except I did it for 15 minutes @120F after pruning all the RKN off of the roots. I chopped the tree down, dug out the main stems of fig trees. I used a 10% bleach solution on all tools before and after use when performing the tree removal process. I usually do it, and in my opinion is a very good habit to develop.

The temp should be enough to kill any remnant RKN. James has reported good results and I will report my results in March some time. Here is a pic of how much I pruned off, the RKN was bad. I made sure to remove all galls using my precision flower pruners. I have these now in papertowels to see if they are going to show root initials. The trees are still alive judging from bark vigor, swelling of tips, and roots looking and feeling health. Here are the pics.

Comments (13)

gorgi
15 years ago
TRY this "quickie" experiment/fix for those root stubs.
Shave them ALL roots (I mean as close as you ever did to your
beard on your face!).
Give them the 10% bleach-treatment+ (for say 10 minutes). Re-pot; fig-root-stubs do re-root VERY, very easily.
Quarantine! Then carefully re-examine the roots (say) next year (or as you deem fit).
Good luck.
gorgi
15 years ago
Two springs ago, I bought a heavily RKN-infested fig plant.
After chopping it down for cuttings, I did exactly as I
said in the above post to the remaining root stub.
Today, in bright sunlight, and almost bare-rooting it,
I re-checked the same stub. Now it is a dual 3' whip
fig tree and is CLEAN of RKN (at least as I can see/tell)!

This is how the roots originally looked when I first got it.
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Yes, all of the above should be of some help. However, I occasionally remind people of a simple, effective treatment learned many years ago. As a furrow/planting hole is made to plant beans, carrots, parsnips, tomatoes, etc. (either young plants or seeds) toss in handfuls of regular granulated sugar and plant as usual. For those with large gardens 40# bags of dried molasses can be substituted for granulated sugar. Available where horse feed is sold. This year we are trialing a dry molasses mix that has dried kale added. This is all that was available here. So far all plantings are healthy and repelling the RKN. For plants that take a bit of time to mature it would be wise to scratch in a sugar top dressing halfway through the growing season. There is still time in your zone to grow some other crops. Give this sugar method a try.
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Intresting about the crab shells. Sure easy enough to find those around here, though I doubt I should collect them from the neighbors like some folks do leaves. I've already been asked by one old farmer if I really thought a vegetable grown in horse poop would be healthier for him than one grown with fertilizer. (I did tell him that in that case it was healthier for the land and maybe the plant and definitely the wallet, which seemed to satisfy.) I will follow the link and read more. And thanks for the info on the nematodes and green mulches. I was not impressed with my first forray into using them last year, so wasn't planning any this year. I haven't given up on the idea of using them, it is just another skill to master when I am doing so much more than I used to. I want to be able to continue to grow melons, they are one of the "value added" crops I can send in to the restaurant and are becoming a big deal. They showed the most sign of nematode damage, though they produced adequately. I'm hoping that a normal winter will return the populations of nematodes to a normal level, which is to say negligable, but planning on taking some action. Just haven't quite figured out which way I'm going to jump.
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Hi George, I wanted to address a couple of issues you raised. Last year I pulled a bunch of rooted suckers off a tree with RKN in my neighborhood. I planted them with the intention of experimenting on them. Most of the suckers had little roots to begin with, and most of the roots which were there were removed. The sacrificed tree I mentioned above was one of these suckers. While moving the container it was in, I dropped it. I didn't really have time to repot it. After sitting bare rooted for a couple of hours, the gals were no longer visible on the roots (hence the warning of receiving bare-rooted trees). The tree did have gals in the new root growth despite being stripped of most of it's roots. I do not know if the RKN can implant themselves in the trunk of the tree. I do remember seeing something that looked like a gal on the trunk of one of these suckers (not this specific ones) when I pulled them. I thought I had taken a picture of it, but have not been able to find it. Also, three of the suckers I pulled were about 2" in diameter and about 4' long. I planted all three of them without any roots left on them. Two of them leafed out. One has since died, but the other one is already putting on new growth this year and looking strong. I'm not advocating stripping mature trees of all roots, nor will I say RKN isn't a bad thing. Those things that we might think of a death sentence for the trees may not necessarily be. ~james
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Well, even with years of fallow or tolerant plants, you're still likely to have nematodes in the soil. They'll be at lower than previous numbers but will start rebuilding their populations as soon as you plant a susceptible crop. When the marigolds are used, the nematodes will infest the roots but won't be able to multiply. The marigold planting must be for an entire season with no other plants in the affected area. The common notion that one can interplant marigolds to prevent, or limit, RKN infestions is nonsense. Jean who gardened for 30-some years in SoCal, all the while dealing with plant damaging RKNs.
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boizeau
15 years ago
It may not cure a fig tree, but asparagus gives off a natural nematode repellant and you might try to plant it around the base of the fig tree. I don't know if asparagus would get enough light there, but I do know it has a record of being toxic to nematodes. Soil pests are really hard to deal with chemically. It is a pretty cheap fix and the asparagus is there for years.

Here is a link that might be useful: asparagus vs nematodes
gorgi
15 years ago
Oh, now that things are getting back to me; after
clean-shaving all the roots and treating with bleach,
I also scrubbed the root-stub with a tooth brush under
running tap water...

As I mentioned many times before, PREVENTION is the best cure!
Do examine ALL rooted figs you get from who-ever.

If RKN ever get into ones garden soil, it is extremely
difficult to eradicate them, no matter how many RKN-
trapping-marigolds are planted, RKN-eating-good-
nematodes (expensive) are applied, or chemicals used.

There is one chemical that nukes the soil (it practically
kills everything!). I forgot the exact name.
But it SO toxic, that it is now illegal and not available
any more.
boizeau
15 years ago
Good luck
And I thought yellow jackets were the worst problem.

Here is a link that might be useful: Nematode control measures
gorgi
15 years ago
Also, as I had said before, some "fig-pests" are very hard
to get rid off. RKN is definitely a one tough-cookie!
(I am very, very lucky and thankful, that my RKN experience
is so far contained).

Here is a link that might be useful: Fig's Worst Nemesis
hlyell
15 years ago
Yes George,
Some "fig-pests" are very hard to get rid of, but they are just doing their "thing" - living their life as a pest. Eventually goodness and diligence wins out over the pests - in the long run.
scott_ga
15 years ago
I wonder what effect this hot water treatment has on fig mosaic?
loslunasfarms
Original Author
15 years ago
Just as an update, the trees shown here were potted into clear pots and I still see NO sign of rkn and all the new root growth looks great.
bjs496
15 years ago
Hi Jose,

I am glad to see you duplicated this experiment. About mid-year last year, I had the same result you did. I partially bare-rooted a Petite Negri, and did not see evidence of RKN on fresh roots.

Scott,

RKN is a bug that lives in the roots of the trees. When exposed to heat the nematodes die. My understanding of viruses is that higher heat is required to kill them. This will probably kill the tree as well. I suppose one could dissolve one of the anti-viral meds into water. I'm not sure if you could convince a doctor to give an Rx for that though.

~james
gorgi
15 years ago
Clarification:
I wrote a LOT about RKN before, mostly mentioning chopping
the young infected tree for (safe) clean cuttings DOWN
to the root-stub just ~1" above the soil surface.

In this thread, by root-stub, I meant so (a STUB!).
A SHORT root-stub (void of any braches) shaved
of ALL roots. NOT the whole tree with no roots -
the root/leaf balance would be 0:X
- of course it will die!

A short clean-shaved root stub should VERY easily
RE-ROOT AND RE-SPROUT...
fernando_grow
15 years ago
is it o.k. to take cuttings from a fig tree that has root knot nematode? will the rkn be spread from a cutting or does it only effect the roots and soil?
gorgi
15 years ago
Yes, it is OK to take cuttings. RKN only affects the roots.
Do not use any (suspect) RKN infected soil.

Root Knot Nematode (RKN), Heat Treatment, and Root Pruning

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Root Knot Nematode (RKN), Heat Treatment, and Root Pruning

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