Development questions on JBP

[NMbonsai]

Hello fellow bonsai nuts. I have some questions regarding the next step in development on a Japanese Black pine.
I have had this nursery stock JBP "Kutobuki" for several years. It has been in a training basket with bonsai soil (A/P/L plus some organics) for two years, but I did not do any work on the upper parts. At the end of January this year (2025), I became concerned about the inverse taper starting to develop at the branch whorls, so I did a trunk chop just above the second whorl and reduced the branches to two at each whorl.
On April 1st, I wired the branches and used guy wires to pull some branches downwards. I started fertilizing the tree last year with Biogold and this January started feeding with a slow release granular fertilizer (17-6-12).
The tree has responded well to the pruning and fertilizing and is producing candles on all the remaining branches. My questions are:
1) Should I not decandle at all this season and just let the tree build strength and recover from the work done on it earlier this year? If so, will the resulting branches grow too long and have to be cut back next year?
2) If I do decandle in about a month (early to mid June), should I remove candles over the whole tree or just from the top (future apex) branches? As shown in the last two pictures, the new growth appears to be pretty equal at both the top and bottom of the tree. It has one back branch near the bottom of the tree that has one very tiny bud near the tip, so I will definitely leave that one alone.
The tree is now about 15 inches tall and I don't really want it to get any taller, just more ramified. As I see it, it has two major design flaws. One is the inverse taper below the graft union with no root flare. The other is the straight section between the top branches and the next lower branch. I hope that these will become less noticeable as the tree ages and fills out.


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[SeanS]

It looks like you still have multiple (2) branches coming off the trunk in some spots. I can see 2 branches coming off the trunk on the left side, the 2 lowest left branches (circled in red).
When reducing to 2 at each whorl you should include the trunk or leader as a “shoot” at that point, meaning you’d only be leaving 1 actual “branch” and the trunk/leader.
How many branches/shoots are coming from the blue circled area?

 

[shohin_branches]

Do you like current height and trunk thickness? If yes then decandle in June. If no then don't decandle but reduce all candle clusters down to two.

 

[Shibui]

t looks like you still have multiple (2) branches coming off the trunk in some spots. I can see 2 branches coming off the trunk on the left side, the 2 lowest left branches (circled in red).
When reducing to 2 at each whorl you should include the trunk or leader as a “shoot” at that point, meaning you’d only be leaving 1 actual “branch” and the trunk/leader.
How many branches/shoots are coming from the blue circled area?

Totally agree. When I read 'reduced to 2 branches at each whorl' I suspected it would still have excess branches. When we talk about 2, the main shoot is included so that's main trunk (or branch) and 1 side branch.
The problem the OP has is that long, bare section of main trunk, which the OP has already pointed out. Unfortunately, that's a reality when working with trees that have been fast grown for landscape. Reducing to 1 branch at each whorl will leave a big gap in the tree.
The choices I see are to :

• design with a big space and fewer branches.
• leave extra branches which will fill the space a bit but risk inverse taper as the branches develop. Note there's already some inverse taper at the graft so maybe it doesn't matter so much?
• Chop the trunk above the lower whorl and regrow a new trunk with one of the branches - probably the best option as it will give both taper and bends to the trunk but long term project.
• graft new branches into the bare section - long term project. Will not address taper but will give better branching structure.

1) Should I not decandle at all this season and just let the tree build strength and recover from the work done on it earlier this year? If so, will the resulting branches grow too long and have to be cut back next year?
2) If I do decandle in about a month (early to mid June), should I remove candles over the whole tree or just from the top (future apex) branches? As shown in the last two pictures, the new growth appears to be pretty equal at both the top and bottom of the tree. It has one back branch near the bottom of the tree that has one very tiny bud near the tip, so I will definitely leave that one alone.
The tree is now about 15 inches tall and I don't really want it to get any taller, just more ramified. As I see it, it has two major design flaws. One is the inverse taper below the graft union with no root flare. The other is the straight section between the top branches and the next lower branch. I hope that these will become less noticeable as the tree ages and fills out.

The wiring and pruning you did should not worry the tree as far as decandling. I would decandle this season to start building ramification.
The shoots appear reasonably equal but all appear equally weak IMHO. I would expect healthy JBP shoots to be way bigger and stronger. Maybe that reflects the mention of only starting fert last season? Maybe cultivar? Maybe some other environment or care factor(s).
Kotobuki is a fastigate cultivar meaning it normally tried to grow tall and skinny. Not sure if that has an impact on shoot strength or length as I have not worked with Kotobuki.

Another thing to consider is the straight branches. I can see you have wired them down but left the branches relatively straight. Consider putting some 3D bends into the branches (up/down, back forwards) for interest. Over time you will be pruning back to side branches which will give such movement but until that time, I think some wired bends would add something to the branching.

The root flare should be addressed at some stage. It will probably require close to bare root to find where the main lateral roots are and, probably, to untangle and lay them out in a radial pattern. Root structure is another big problem with fast grown commercial trees grown for landscape. They are started in small, round pots and upsized as they grow but the circling roots are rarely worked so most of these trees tend to have circling and tangled roots - OK for landscape but not so good for bonsai.
You'll also need to (gradually) reduce any down roots. When lateral roots are doing most of the work for the tree, basal flare will happen. Given enough time the base of the trunk may even swell enough to hide that graft but, given you are moving to limiting growth and building ramification by decandling any trunk thickening will be very slow.
While the roots are tangled and the tree can rely on deeper roots instead of laterals the trunk will be even slower to develop basal flare.

 

[NMbonsai]

It looks like you still have multiple (2) branches coming off the trunk in some spots. I can see 2 branches coming off the trunk on the left side, the 2 lowest left branches (circled in red).
When reducing to 2 at each whorl you should include the trunk or leader as a “shoot” at that point, meaning you’d only be leaving 1 actual “branch” and the trunk/leader.
How many branches/shoots are coming from the blue circled area?

View attachment 595284

Correct, there are two coming off the top whorl as well, but they then branch into four. At the red circle, one branch goes to the left and one goes to the back. I figured it would not appear as a bar branch because it opposes the other at 90° instead of 180°. It is also the weakest branch on the tree, only showing one very small candle. The lowest branch, going to the right, is single.