Need help!

[Mat_bonsailover]

Hi all,
I have a Ficus Benjamina which was having scale issues and been treating it for a few months now. However, I saw some flies at the bottom of the nebari and digged in a bit and saw that the whole area below nebari was full of some yellow stuff as in the pictures. Cant figure what it is. Please could you help to identify if this is some kind of larvae, maggots or fungus? The tree is kept indoors in artificial lighting for past few years. I have been using neem oil and also brunnings Bug killer intermittently for past few months.

Cheers,
Mat

https://www.woolworths.com.au/shop/prod ... lsrc=aw.ds

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[shibui]

Your ficus looks very healthy so no immediate cause for concern. It looks like it is starting to get quite tall and leggy so probably high time it was pruned a little harder but that's best done through the growing season during warmer weather.

The photos are not clear enough to be definitive but my guess it that's a fungi or mould of some sort. I assume you did not see any of the yellow stuff moving when you uncovered it?
While there are a few fungi that attack trees, the vast majority are harmless and just help break down organic matter.
Provided the tree stays healthy I would just continue care and watch for any changes before rushing to nuke the soil.

If the flies you mention are tiny it is likely they are fungus gnats. Just a coincidence in naming, not related to the yellow fungus in the photos except that both thrive in constantly wet conditions. You may see larvae which are small white maggots in the soil
Try letting the pot dry out a little more before watering each time. If the pot sits in a saucer as many indoor plants do, consider raising the pot above water level on tiles, gravel, so it never sits in a pool of water.

[TimIAm]

This growing season I've worked on a few larger benjamina that have resulted in some patches of dieback on the trunk. I noticed that the outer bark becomes detached and whenever I've removed sections of bark where dieback has occurred there where small larvae/maggots of some sort, even when the section of dieback was not at the edge, so I'm not sure how they are getting in there. They were fairly easy to remove and didn't return once the section of bark was removed.

This is just a suggestion as I don't have your tree in front of me, but is it possible the large root shown has died off, leaving decaying bark which could attract the larvae? You can tell if the outer park is soft and spongy like you could easily peel the whole bark off by hand.

[Mat_bonsailover]

Thanks Shibui & TimIAm, the yellow stuff is not moving and looks more like mould. I went again and poked the side of the root/ bark where this happened and it seems like rotten in pictures below. The area was soft and spongy and disintegrated when poked. Didnt notice it until now since the tree looked healthy and growing this whole summer. The tree never sat in water and has been watered once top soil is dry for two cms. The tree was also repotted last Sep.
Would you recommend me repotting the whole tree to remove the area? Also am I right that I have missed the boat in pruning hard since its already going into winter soon.

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[TimIAm]

With Ficus you don't need to worry too much about missing the boat with an above-ground prune, long term there won't be much difference if you hold off until it warms up again.

What you really want to know is when you can carve out what is rotten and how to protect the rest of your tree. In Sydney it's still warm and my ficus are still pumping out new growth. Just hold off until Neil replies as he would be closer to you (in climate), as I'm not sure if you are heading into winter if now is a good time to carve out the rotten section.

What I am concerned about is how wet/damp the soil is typically? As you are growing indoors with less evaporation and your soil mix looks like it has plenty of pine bark in it, it may be too damp. Ficus like to be watered but sitting in constantly damp soil mix is not going a good idea.

[shibui]

I do not like the look of those new shots. Definitely something going on down there but, as mentioned above, it could just be the organics in the potting mix that's decaying. The top is so healthy it is hard to believe the roots are compromised. Does it look like any roots are soft and rotted?
For most of us it is past optimal time for repot but this one lives inside where, I guess, it is much warmer than most so repot is not out of the question.
It probably comes down to the lesser of two evils. Is the tree more likely to die of root problems or more likely to die from repotting? Chances are it will cope with late repotting because it lives inside and is relatively warm through the entire year.
If you decide to try repotting I would cut/comb out as much of the affected area as possible but would not bother going into areas that are not affected yet just to reduce the amount of regrowth the tree needs to do after. As it was repotted in spring there's probably little need to cut roots hard, just comb out the affected soil and repot with fresh mix. I've also seen Hydrogen peroxide used as a soil drench to treat fungus infestation in pots. H2O2 is also very effective against fungus gnats but be warned, after you apply the diluted H2O2 solution, the soil will bubble up almost like a volcano but it all drops back into place after the reaction is finished.
If you decide not to risk repotting you may be able to manage the problem through winter by keeping the pot on the slightly drier side, even to the point of the new shoots wilting a little before watering again. Ficus are really quite drought tolerant so can cope with remarkably long periods with little water.

[Mat_bonsailover]

Thanks both, I'll repot the tree, clean the affected areas and use some peroxide to clean up the roots and soil around it. Might also use the opportunity to prune it as well. Thanks for the heads up about the volcano reaction of peroxide since would have freaked me out.
Will let you know how it goes