I am happy to report that I successfully killed root knot nematodes that had infested four plants.     Last repotting season I identified four infested container grown figs (nematodes came with soil from another location).   I did some research on our forums and other sources for remedies.    I settled on one that definitely worked.

Congrats. Will know what to do in the future. That's the fun in figging. Thanks for letting us know how it works.

Paully22

Byron,

Glad to hear of your success.
It is our everlasting endeavor to find ways to rid our beloved figs of pests and diseases.

Sounds like an awesome concept, but in reading it, I'm reminded of one of my first epiphanies in chemistry class.

One thang that blew my mind in my first real chemistry course was discovering 'physical change' and 'chemical change'.  Our teacher posed the class with scenarios and openly asked whether the change was physical or chemical.  Example:  water turning to ice or boiling a potato.

Long and short:  If you can't reverse the change, it's probably a chemical change. 

So, in the case of water ... water freezes to ice, ice melts and becomes water.  Whether water changes to ice or ice changes to water, it is still H2O - it's a physical change (state change).

In the case of the potato, if you boil a potato, it's forever changed.  You can't go back to having a raw potato again - it's a chemical change.

The whole point to this ... A potato is a tuber, basically a root.  If you boil a potato for 20 minutes it turns fairly soft and mushy.  With that in mind, it sounds like this method is probably cooking the nematodes to the point of death, but you're also all but killing the roots, turning them into mashed potatoes, and you're basically re-rooting the cutting from scratch?

It seems like airlayering would be safer, with a higher success rate?

I appreciated your thoughts about the situation and I too was concerned that I had "overdone" it.     When examining the roots, they all generated from the roots that I had left on the plant - roots had not restarted from the stump of the stem.    Also, the roots were not physically close to being boiled since there is a big difference between 120 F and 212 F.  The feeling that they had been "boiled" did cross my mind.     The idea behind this of course was to find a temperature that did not kill the plant but was hot enough over a period of time to do the job.   I surely pushed it a bit...

ah!  Fahrenheit.  i totally read 120 Celsius.  for some reason i thought you were one of our Canadian friends.  feel free to kick my ass if we ever meet up IRL.  ;)

No problem -   If that was Celsius, it would have certainly would have become a "mashed potato!"     In Celsius it would be around 49 deg.   Thanks for your reply.

120 C cooks whole potatoes in 6-8 minutes in my pressure cooker at 15 psi (with natural cooldown), I love it.

I remember reading about a similar treatment for banana pups but am not sure what the pest they were killing was. I think they actually did use boiling water and only dunked for like 15 seconds.

I tried this hot water method a couple of years ago. It was hot water straight from the tap and I didn't use a thermometer. We have our water heater cranked up to high all the time. I dipped the affected plant for 5 - 10 min. It was potted up and put in the greenhouse, this was in fall. In spring it never came out of dormancy. It sounds like it would have been good to use a thermometer! I've pretty much settled on doing airlayers to side step the nematodes but its good to know that under controlled conditions the hot water method works. Thanks for sharing!

Since we are considering a move to a different area with in-ground trees I'll admit the idea of having these nematodes in the soil makes me shudder.  I'm more of an expert wine grape grower than figs, but that cooking trick does well to eliminate some vine diseases, so it should work fine with figs!  Nice to know these remedies in case bad discoveries are found!  Thanks for posting.

I plan to use the jacuzzi should this ever happen!  Should make the pool guy happy....  I can see him shaking his head.  He already thinks I'm crazy, and if I do this, that concept will be in concrete! :-)) 

Suzi

My husband uses a similar method to kill chestnut weevil larvae in the nuts from our chestnut tree.  It takes 20 minutes in 120F water.  It totally eliminates the worms, but the heat doesn't kill or change chestnut embryo.  The nuts taste exactly the same, too, as they would without the heat treatment.  

According to the American Chestnut Foundation, "If the temperature is too low (less than 117'F), the weevil will not be killed.  Too hot, and you kill the embryo and, thus, the seed."  I'll bet you have to maintain a pretty tight control of temperature with fig roots, too.  I'd invest in an accurate thermometer. ;)   

Mimi