Hello Everyone,

I've posted on this forum about a scale & fungus gnat infestation on my tree last year, and this year they are back! I guess I didn't get them all. Also, I've repotted the tree 2 months ago and to my horror, the roots were infested with root-knot-nematodes...talk about annoying!

lLast year I picked off all the scales I saw (since my tree is only 3.5 feet tall) and lightly dabbed the leaves and bark with alcohol, which seemed to help with scales for the season. I'd see one or two, but those were easily squished.

The RKN are more of a problem though. Sadly, I was only able to root-prune when repotting and wasn't able to put the roots in hot water to kill the nematodes and their eggs. I've heard of soil solarization for in-ground plants and I'm thinking of doing it with my potted fig. I live in Hong Kong, so it gets relatively hot and humid in the summer. I'm thinking of wrapping the pot in black tarp when it gets hot enough for a couple of hours to kill off the bugs(hopefully). For the gnats, I'm going to try to sprinkle cinnamon on the soil and for the scales, I guess I'll just squish em.

If any of you have a recommendation on how to save my tree, I would be so grateful, as I'm new and just searching for solutions online! I know I should probably get rid of it, but it's just given out new leaves and 2 brebas and I don't want to let it die, the figs are white and sweet so if any of you can help me destroy these bugs I would be really grateful!

Thanks so much!

there are few posts about RKN on the forum. hot water therapy, heavy mulching.. i'm hoping i'll never have to deal with RKN. 

Thanks bullet! Yeah, RKN are terrible, and the roots look horrendous when infected. I can't say whether RKN or scales are worse though.

Going to try the 50/50 hydrogen peroxide solution I saw in the forum! As for mulching, can I use oyster shells on potted plants? What is it about oyster shells that the RKN hate? Thanks!

not sure i haven't read about oyster shells. but oyster shell should have lot of calcium. not sure if there is lime. about the only think i know about RKN is.. if it's in your yard, it will be almost impossible to get rid of. and they like sandy soil. mulching it with pine bark/needle keeps the zone moist and they don't see to like that too much. i believe some members in FL have RKN in their soil, but still grow rather nice trees with heavy mulching. on the other hand, i know of at least one member who grows everything in containers, and when one of the plant came in with RKN, number of them got infected and he had to do some serious repotting an cleaning up. 

i grow all mine in container since i have no clue if we have RKN in our soil. i'm pretty sure i don't. but don't want to even thinking about dealing with it. 

Yeah, I think the problem is once you treat the roots, you're still a bit paranoid if they are really all gone. I'm going to try the peroxide solution and cross my fingers. I'm also going to experiment with solarizing the container (I hope it doesn't kill the tree). Between the cinnamon, peroxide, soap and solarization, I hope the bugs just leave my container alone. :(

I have read that certain varieties like LSU Gold are resistant to RKN.  Could you maybe graft some scions from your tree onto an LSU Gold tree as root stock?  Or, air layer it now, and start fresh?

Suzi

You can start a few cuttings in clean soil. If your in ground soil is infested, do not use it at all, or at least cook it first.  Elevate the clean pot on some bricks or something to prevent ground contact.  I don't know of a way to sterilize infected soil and roots without killing the plant.  It might be possible, I'm just not familiar with it.

If you can find a RKN resistant variety, you can then practice grafting.  There are many instructional grafting videos on the internet.

I've often thought the reason RKN don't live under concrete slabs and large boulders is the lack of oxygen in those places.  Sandy soil allows oxygen penetration.  In theory, if one was to place a large trash bag over a potted plant, place a small candle on the soil surface, and tightly seal the bag against the plant trunk for a day, it could kill anything requiring oxygen.  Just a theory though.

Step #1: QUARANTINE the plants with RKN.  Their natural mobility can be measured in inches per year.  Wind, water, gardening tools, etc. all help them move much further.  Move them as far away from other trees as possible.

Charles' thought on O2 might be helpful, but the life cycle of RKN is about 2 weeks.  One could set the container in a larger tub and sublimate dry ice in it.  I do not know if this will work, but one would need to do it daily for a few weeks to make sure kill the hatching nematodes.  Another method would be to fill the tub with 150F/65C degree water and put your container into it.  Measure how much the temp drops once the container goes in.  You'll want the final temp to be about 125F/50C degrees.  Leave the container in for only a 3-5 minutes.  You want to kill the nematodes in the growing mix, not those in the roots.  Repeat every 3 or so days for a couple of weeks to disrupt the life cycle and reduce the numbers in the container.  Bare-root and completely heat treat the tree once it goes dormant.

It is possible/probable the other pest problems are tied to the RKN infestation.  The infestation of RKN (especially in a containerized tree) severely distresses the tree reducing it's vitality and making it a prime target for other bugs which will feed on it.  As for nematode resistant varieties... I have read many times that LSU Purple is RKN resistant, but no where have I seen WHY  it is resistant.  I can speculate it is due to LSUP being an aggressive root producer allowing it too outpace the natural movement of the nematodes.  If this is the case, it does no good in a container. 

Eggs require O2 also.  How much, I'm not sure, but depriving oxygen should kill eggs.  Measuring O2 requirements of RKN eggs would be a good experiment for a student.

http://www.aviagenturkeys.com/media/146026/atl_incubator_ventilation.pdf

Hi,
Because the tree is in a pot, I would quarantine it over concrete .
Then fertilize that tree the most I could, and at the end of the season airlayer or take cuttings of the top of the tree.
Once the small trees are growing and producing, burn the poor first tree ...
Life is hard !
Do you have nematodes in your garden dirt ?