A while back there was a somewhat contentious thread concerning root knot nematodes on figs.

Later a poster stated that he had purchased figs from Mr James Robin of Opelousas, La that appeared clean.  According to that post Mr. Robin had stated that his figs at one time had RKN but that he was now using sugar in his potting mix and had no nematode problems. 

I subsequently ordered a fig from Mr. Robin and it came in strong, healthy and apparently free of RKN. 

I also noted posts by James mentioning scraping a piece of root before planting to see if  he could get a plant free of RKN, and another mentioning a fig with brebas that was, as I understood him, infected with RKN.

What do you all know about treatments for RKN?  Sugar would probably dry out the boogers on the outside of the root.  Do all the nematodes at some time have to exit the roots? 

If sugar is effective it should be a quite practicable treatment for potted figs.
Ox

Ox,

Someone on the tomato forum posted this link to beneficial nematodes that may be useful:

http://www.gardensalive.com/product.asp?pn=5004&bhcd2=1207110414

Here is their claim:

With just one application of Beneficial Sf Nematodes, you can achieve 100% control of root-knot nematodes, and greater than 80% control of ring nematodes and sting nematodes, according to field trials. Root-knot nematodes can be difficult to diagnose because they do the most damage underground. Aboveground, symptoms include yellowing of leaves, stunted growth and loss of vigor.

Our strain of beneficial Steinernema feltiae (Sf) nematodes is highly effective against destructive nematodes. 10 million Sf Nematodes will treat 200-300 sq. ft., and one application provides at least 3 months of control. We ship at the proper time for your area, or on the date you specify.

If I ever run into RKN...knock on wood...I will give BN's a try.

Sue

According to people has suffered it, the best option is to airlayer (it is a foolproof rooting method) a branch or the main trunk of your suspect tree and, once a successful rooting, discard the original tree. There is an Spanish proverb that says " The dog died, the rabies ended"...

The fight against root nematodes can very frustrating and risky, they frequently win the battle.

The sugar Mr. Robin uses is to treat the soil as a measure to prevent initial infection of the plant by RKN.  Sugar (from what I understand) will not help if the roots are already infected.

When he had his RKN problem Mr. Robin was potting his rooted cuttings in pine bark mulch he had bought in bulk.  This truckload of mulch turned out to be infected with RKN.  He got rid of it and began using a different potting medium.  He is using the sugar treatment just as an added precaution when he pots up his rooted cuttings.

Since he changed his methods and destroyed a lot of infected plants I have gotten quite a few trees from Mr. Robin.  The ones that have been potted since he changed his methods and rooting medium have been very healthy and completely free of RKN.

I have a few RKN-infected trees now, and I may give the treatment Sue mentioned a try as an experiment.  As Axier suggested my plan was to airlayer them shortly and discard the infected roots.

However, I am very interested to learn the outcome of James' experiment with heat-treating RKN-infected roots.  I think he will be able to reach a conclusion about this method's effectiveness this fall when his trees go dormant.  The good news was that his trees survived the process of heat-treating the roots.

Henry

I found a few of web sites that describe the life cycle of RKN,
which may help us understand and defeat the buggers.

http://vegetablemdonline.ppath.cornell.edu/factsheets/RootKnotNematode.htm

(skip the Migratory kind, got to Sedentary -)  http://mint.ippc.orst.edu/nemacycle.htm

http://en.wikipedia.org/wiki/Root-knot_nematode

http://www.ext.vt.edu/pubs/entomology/444-107/444-107.html

Though all 4 sites have some significant info/pics; I find the last one as
most informative (with conjunction of earlier info of the above 3 - read all!).

George (NJ).

When the use of sugar was mentioned I deduced that the manner of action would be to dehydrate and kill nematodes that came in contact with it.  If that were the case, only nematodes outside the roots would be killed. 

Since juvenile nematodes all leave the roots, over time all the nematodes would be killed other than the breeders in the roots.  Eventually they too would die if the dessicating environment was maintained. 

This would be an unlikely case for an already-infected plant; regular watering would quickly  remove any sugar in the pot. 

As a treatment for potting soil used to root plants it might be effective.
Ox

Ox, up to this point I have only tried heat treating (soaking roots in hot water then repotting in clean medium) and air drying (tree left bare rooted for two hours then repotted in clean medium).  Trees treated both ways have survived.  As Henry pointed out, I am waiting to see if the nematodes did.

My understanding is that sugar somehow dislodges the nematodes and allows them to be flushed out with the water.  Sugar does not kill the nematodes.  I have seen several papers (or at least the abstracts... the papers are for sale) which describe (the abstract claims the paper describes) the process of using sugar to extract nematodes for laboratory experimentation/analysis.  From a Texas A&M paper:

Sometimes people resort to using home remedies to control nematodes such as planting marigolds or mixing sugar or lye into the soil. Of these three, only French marigolds are effective in controlling nematode populations, and their effectiveness has limitations and is often questionable.

• When M. incognita and S. feltiae were applied at the same time:  Neither M. incognita penetration rate nor developmental rate was affected by S. feltiae application. Egg production per plant and egg hatch rate were significantly reduced in the treated plants. However, the number of eggs per egg mass in treatment plants was not different from that in control plants.
• When  S. feltiae was applied to sand containing M. incognita infected plants:  Development of nematodes inside the root was not affected by S. feltiae in the sand. Galling 6 weeks after the application was again less in the treatment than in the control plants.

As far as the multiple threads about this very serious fig (RKN) problem, I still think
that the BEST cure is PREVENTION. Once you get it, LESS than nuke'ing the
place; ForgetAboutIT!  Examine  your newly  bought/given fig roots, mostly from
maybe naive sources.

To summarize, it appears that the best method of treatment for RKN as of the present time is a new plant from a cutting put into a clean pot. 

I live on a sandy place; sand for miles in each direction.  I know that there are nematodes present so those figs I put in the ground will just have to deal with them. 

Pots are a different matter. 
Ox

Hi everyone, I'm new to the fig forum, been reading lots of the interesting information you guys put on here.  Anyways RKN here where in live in north Florida are prevelant in these deep sandy soils and attack about anything of value.  One my friends Eliminated and prevents reinfestation with compost/consisting of 75% manure (horse/cow) or higher. It's taken her several years, but there's been 3 years now no damaged seen, and her soil samples keep coming back negative for RKN.  She tills it into new , or garden soils, and keeps everything mulched/top dressed with it.  I have read there are three common fungi (the names escape me at the moment) that breakdown proteins, and make mycellae (i know i spelled that wrong) webs in the soil that nematodes stick to and die as well as the fungus attacks RKN egg cysts (encapsulated in chitin, a protien).  I also know the farmers here in their gardens etc, always till in as much manure/organics as they can to wipe out or knock down nematode populations for the year. If you try to use the manure approach, you can't use fertilizer's containing sulfur, as this is a potent  fungicide. Also  I have a neighbor that swears he got RKN out of his large Brugmansia pots by using three Neem oil/water soaks, of the whole pot every two weeks.  I've also noticed under china berry trees (which is a cousin to the neem tree) the RKN weed hosts i.e. pussley, will be more vigorous and have flawless roots which  in this soil is unheard of. 
Just some ideas to throw around.  I'm eliminating RKN host plants from my property, and the places i'm planning to put my fig trees I'm making compost beds, which should eliminate RKN.  Now I just have to figure a way to prevent reinfestation, because nematodes here move fast through soil especially after heavy rains, and the egg cysts blow around with dirt/dust, how great is that!!!  Just some ideas, hope something helps:)