Absolute newbie - help with rot

[Aradiel]

I am an absolute newbie when it comes to bonsai, and am in need of help

I inherited this particular tree from a now deceased relative, so I don't know what species it is

I bought some specific bonsai feed that said to be used once a week (twice during growing periods) - if anything I've been negligent and fed the tree less than that

When I first got the tree the trunk was grey. I would normally pour the feed into the soil, but found that pouring it directly into the trunk made it turn brown and look more alive.

However, the bit in the middle of the trunk looks as if it is rotting (it certainly looks like it when I have the light turned on, it's much harder to see in the daylight)

Is it rotten? What would be a good way to fix this (I'm worried that since it's so central, cutting it out would risk the integrity of the rest)

I've seen some mention of chemicals to use after cutting out the rot - would rubbing alcohol be good or bad for that?

Thank you for your patience and I would appreciate any advice

 

[Brian Van Fleet]

It is some type of grafted ficus, and it looks like the scion has died back (which is the circled part you are likely describing as rotten). It appears that the rootstock has budded and is now growing. Not altogether bad, just large leaves.

Typically we carve away rotten wood, careful to not damage live tissue, and make the edges smooth so callus tissue can grow over the carved area. Then we ensure water has a way around (or through) the dead area, then seal it to protect or delay further rot.

 

[Aradiel]

It is some type of grafted ficus, and it looks like the scion has died back (which is the circled part you are likely describing as rotten). It appears that the rootstock has budded and is now growing. Not altogether bad, just large leaves.

Typically we carve away rotten wood, careful to not damage live tissue, and make the edges smooth so callus tissue can grow over the carved area. Then we ensure water has a way around (or through) the dead area, then seal it to protect or delay further rot.
View attachment 613901

I think I understand the carve away aspect - I've got some scalpels I can use. I'm not sure what you mean about water going around the dead area - I could just pour the water on the soil (or did you mean internally?)
What would be recommended for sealing it?

 

[Brian Van Fleet]

I think I understand the carve away aspect - I've got some scalpels I can use. I'm not sure what you mean about water going around the dead area - I could just pour the water on the soil (or did you mean internally?)
What would be recommended for sealing it?

First, carve the dead area away, and leave it concave, except an area that forms a bit of a “spout” so water doesn’t pool up in the center. If that isn’t possible, sometimes drilling a hole straight down and through allows water to drain away. Carving can be done with whatever you have that will work. There are bonsai tools made for this kind of work called knob cutters and concave cutters. Here is an example of carving you can aim for.


Second, for watering, yes, you water the soil and don’t worry about trying to get the trunk wet.

Finally, to seal a wound like you’re creating, use something like this.

 

[Shibui]

I'm worried about the soil this tree is planted in. Looks very wet and some of the roots have suspicious marks on them that could mean more rot down lower. Soggy soil is the biggest killer of indoor bonsai. Water needs to drain through the soil and out of the bottom of the pot to drag fresh air into the soil. Soil should be allowed to get almost dry before the next watering. Pots sitting in a saucer of water aggravates the problem.
Please check all roots for soft, rooting tissue, especially close to soil level.

 

[Aradiel]

Thank you all for the advice so far - I spent a good couple of hours carving away at the top of the section Brian circled, which was hard work. I'm not actually sure the wood was dead, as it was moist to the touch but still yellow in colour.
However, in the middle of it there was this dark section, as if it was a dead branch the rest of the tree had grown around.

I didn't manage to get to work on the other severed branch.

Perhaps I'm mistaken and the trunk isn't rotten?
It's certainly not squishy.

I've been trying to watch some videos to get a better idea and think I'll need to check the roots. I'll also see if there is a nursery near me so that I don't end up buying more things than I need.

 

[Deep Sea Diver]

Welcome Aboard Bonsai Nut!

(Adding on the @Shibui above comments).

Whoa! Not sure digging out the tree roots is the best idea unless the other parts of the tree are in poor health. This might cause damage …… Instead, try drying out the media a bit more.

First please ensure all drain holes are clear. Next chock up one side of the pot with one drain hole at the lowest point. This will lower the water table, hasten drainage and overall slowly dry the media. Once it gets to barely moist, return to the horizontal position, water lightly yet thoroughly and see how the tree responds.

Cheers
DSD sends