Neat works james, let us know how it works out.

-jbs

What is the exact temperature needed to kill RKN?

there seems to still be some debate as to the time and temperature requirements to kill the nematodes... perhaps it is a sliding scale. I've seen temps between 110-120°F and times between 10-30 minutes. I think the bigger question is at what temperature do you kill the tree.

I called to secure cuttings for next year from a PN tree I sent out last year before I started. This helped make the decision to try this procedure.

I should know in a couple of weeks if the trees survived... and by next December if the nematodes did.

~james

James, since you have the tree barerooted, is there anything that can be applied to the roots to help increases the death of any remenant RKN?

I'm not aware of any chemical agent to put on the roots. Stripping the soil away and letting the roots dry out removes any mobile nematodes outside of the roots. The heat is suppose to kill the nematodes which have already nested in the roots and hopefully any of eggs they may have laid.

I have two rooted suckers from the first tree I found with RKN. I am planning on soaking one in Hydrogen Peroxide on a bi-weekly schedule to see if it kills the mobile nematodes. If it does, I should be able to disturb the reproductive cycle. If I find another pair of trees to experiment on, I will try putting sugar in one of the containers.

If there are other suggestions on how to kill nematodes which have burrowed into the roots, I'm sure I'll have other trees to try them out on... so long as they don't poison the figs. Most of the other remedies for RKN has been geared to killing/removing them from the soil and not from the roots.

~james

I have the following trees which I found to be infested with RKN during repotting this year:

• Heat treatment: 4 trees

• 2 hour root exposure to dry, windy air: 3 trees

• Removal of all roots with visible gals: 2 trees

• Untreated: 3 trees

All of these trees have survived their treatment and have broken dormancy. Time will tell if the nematodes have.

~james

James did you ammend the soil at all? Compost, manure, marigolds, ?? I read also that heat in the soil help kills,are you using your air-pots or are you putting them in black nursery containers? Thanks.

All of the trees I heat-treated along with one which was air-treated, are in air-pots. The rest are in various 1-3g nursery containers except one which is in a 4g white bucket.

I did not add any amendments to the containers. I did this strictly to test which methods work. I am hoping that when they went back into the containers, they were RKN free. I used fresh growing mix and threw the old stuff away.

~james

James, I read one of the threads posted by Jon in his 'Figs 4 Fun' forum that citrus skins are good nematode deterent.

Paul,

I had also read Neem Oil acts as a deterrent. If I get a chance, I am planning on applying a Neem solution on a weekly basis to see if it sufficiently disrupts the life cycle to kill theme all off.

~james

James,
This is a great post and experiment. Thank you for sharing. I have been reading about repelling nematodes with natural substances. It seems that Marigolds (tagetes lucida) repels nematodes. I can't find the link but a recent read indicated that companion planting is not the method but rather integrate the material into the soil. I do not have a nematode problem to test but I will be planting marigolds.
Richard

Richard,

From what I understand, Marigolds (along with Elbon Rye) are nematode traps. Marigolds produce a toxic chemical within the roots that prevent RKN eggs from hatching. It is believed that once the Marigolds are shredded and turned under the soil, the chemical will spread and reduce the number of nematodes in the soil. From an Alabama Cooperative Extension document:

A few marigolds scattered through a vegetable garden will not control plant parasitic nematodes. For effective nematode suppression with marigolds, solid seed the garden with a recommended cultivar from Table 2. Maintain the solid stand of marigolds for at least 2 months and then turn them under with a plow or rototiller as green manure. Keep the treated area weed free until the next vegetable crop is planted.

I have not seen evidence to suggest nematodes are more attracted to Marigold roots than the roots of other plants. I think without this feature, planting Marigolds around a fig tree will only produce marginal benefits. Especially since you cannot turn them into the soil without also damaging most of the fig tree's root system.

For cover crop the French Marigold (Tagetes patula) 'Tangerine' seems to have the widest coverage. It is effective on Norther, Southern and Peanut RKN.

~james

Potential anyway.

Due to a mishap in my backyard on Monday, I happened to destroy the container containing the Petite Negri (the same one pictured in the bucket of hot water in the pictures above). In order to repot it, I had to partially (about 40% of the root zone) bare-root the tree. All of the exposed roots were new root growth. None showed any signs of gals.

Houston has already reached prime RKN activity temperatures. I would expect if RKN was present in the container, it would have been evident on at least a few of the exposed roots.

Unfortunately, I was not able to completely bare-root the tree. Also, the remaining root ball was falling apart pretty quickly, so I could not spend too much time thoroughly inspecting the exposed roots. However, I am very encouraged by what I did not see. I will bare-root all of the trees at the end of the season.

~james

This is great news James. I guess this winter my wife will not be happy when I start putting barerooted figs in our bathtub :) Great work!

Henry

So james,
Did this treatment work permenantly?
Should I try to place the RKN infected fig in a container with hot water for 10 minutes?
My other test was to place it in a bucket with water and clorox.

Bass

I just performed this on two trees that surprised me with RKN when I went to inspect the roots. I root pruned all the RKN off, it was mostly on the finer roots. I will post the results next season.

Do you think that if the roots were shipped with other bare rooted trees and they're all touching, do you think the others are infected?

Bass,

The heat treatment process is suppose to kill all RKN and eggs. It is only as permanent as one can prevent re-infestation. One of the things to note, I cut off as many of the larger diameter roots as I though the tree could be without. It takes longer to bring the center of the thicker roots to temp.

I have not bare-rooted my trees, yet. Most of the trees I heat treated, did not survive the summer. This was not because of the heat treatment. Rather, there was some difference in the micro-climate of those trees (along with trees close to them) which caused them more grief before Ike hit. The PN I showed pics above, was one of the casualties.

I will have two trees which were heat treated to check on. Also, I have two trees (the Esfehani tree I got from you) which were air treated... left in the sun and wind for over an hour which survived. I'm hoping to bare-root and replant before the end of the year.

If the trees were all packaged together, I would proceed as if all were infected.

~james

James,

Did you ever bare root the two surviving RKN figs you heat treated? I've got a couple of RKN infested figs that I need to make a decision on before they break dormancy and I was hoping to learn if your treatment did the trick.

posturedoc, take a look here:

http://forums.gardenweb.com/forums/load/fig/msg1223023831578.html

It work even better in conjunction with root pruning. I cut off all roots that had knots and treated for 5 minutes. If the tree was bigger I would treat for 10 minutes. If the tree is to small I would be afraid to cook it.

Here is a link that might be useful: Heat Treatment Results

Posturedoc,

The RKN trees I treated either died as described above or did not go dormant for me to bare-root. I did sacrifice an RKN infested tree that I cut the roots off as George described above (without any kind of scrubbing) and repotted in mulch. The RKN persisted in the roots of this tree.

Also, as we are inspecting the roots of the tree, it is important to note that once the roots of the tree are exposed, the gals will disappear over a short period of time. If you are receiving bare-rooted trees, it is still a good idea to quarantine the tree.

~james

Hi Bass,

Though I did post a lot about RKN in many posts, not in
this one. So I guess you meant to a link 2 posts above...
I just added a "clarification" to to that thread.

I am very surprized that a "well-seasoned" plant person
ever needed that and dare "sagrifice" a plant without
even first asking (some) queastions...

Here is the clarification.

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 (cleanly) AND RE-SPROUT...

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

Bass:

First of all I am glad that you did not sacrifice
any one of your one-a-kind precious figs because of
any of my mis-info.

>>> The tree did have gals in the new root growth
>>> despite being stripped of most of it's roots.
NOTE: the word "most". Shaving means ALL roots
less (of course) the skin/bark.

>>> I do not know if the RKN can implant themselves
>>> in the trunk of the tree.
That is THE EXACT question I asked myself at that time!
After an quicky research, I came to the conclusion that
(baby) RKN (pest) only attacks roots (I have NO proof).
HENCE my shaving of them all roots.

Others:
I was one of the VERY first to alert you-good-fig-people
of this very serious fig problem.
Like some of you, I was also naive, I had never heard
of it before, till it was given to me.
BEST cure is prevention, aka EXAMINE all rooted figs
obtained. If suspect, quarantine and DO NOT plant
anywhere on your property, specially if (maybe unknowly)
it was clean before.
After any contamination, healing may be just about impossiple.

Here in another pic of what I am talking about.
After seeing this pic, anybody that does not
throw-up/raise-back-neck-hair/or-similar
does NOT belong here.

And certainly should not (knowingly) distribute figs
with this ailment.

Gorgi,
i never saw that before on mine and if i did i would run!
No really that looks really nasty i would probably just take some sticks and start over but i know for some its different situations
Martin