I believe that it will aid your thinking to accept that the foliage is the source of all energy. Cutting off buds or foliage does NOT save energy, but does much the opposite.
Secondly, if you are wanting to learn from the tree, realize that you can do something to a branch and not have much, if any, effect on the others. In other words, you don't have to leave all the branches be as they are, just a few, maybe. You could try cutting off the semi-aborted buds from a few branches. You likely will not get a new terminal bud to replace it, but give it a try on a few branch tips. Cutting off part of the normal foliage on a few others might be more/less effective in releasing a fascicular bud from the base of some needle groups (of 5) than just cropping the semi-aborted buds. In both cases, this might not be apparent until next spring. Simply breaking off part of the semi-aborted buds, instead of removing them entirely might work as well. This is a technique used on many species, though it is usually done in spring as the new buds/candles are extending. Of course this brings to mind the possibility that one or more of these doings might be more effective done in spring instead of now, but you can figure that out by tagging the branches with the treatment you've given them and waiting to see what happens.
So, you've got possible treatments you could apply
- nothing, just leave it be
- remove part of the semi-aborted candle
- remove all of the semi-aborted candle
- cut further back so that it removes part of the older needles
And you could apply these treatments
- now
- next spring, say after it starts pushing whatever buds it has
That is 8 groups of branches to tag. And since trees tend to be more vigorous up top than down low, you may want to spread your selections along the length of the trunk. Some different color paint representing each treatment is a good way to tag branches (it will wear off long before this becomes your prize bonsai). Take pictures and keep notes. By this time next year you will know just about all there is to know about what you can do above ground, aside from optimizing the timing (that is a lot of future iteration).
You also want to keep in mind that auxin is produced by buds and leaves, but primarily by the bud at the very tip of a shoot (i.e., a terminal bud). Auxin flows down the stem in the cambium to the roots and it is the 'rooting hormone'. It is what stimulates the growth of your tree's roots. The more auxin and carbohydrates that flow down a branch the thicker it will become. Auxin also suppresses buds from activating/pushing.
So, when you decapitate a branch in some fashion, it tends to release buds below (toward the roots) where you cut. All of the 4 main ideas rest on this principle.
The last thing that deserves some thought is that the tree may have or have had root problems. The semi-aborted candles could be a symptom of the tree been neglected and become desiccated when it needed the water to puff up cells to express this year's new needles. If the pot is draining well, I would not contemplate messing with the roots by repotting next spring --> normal bud and needle extension next year would tend to confirm this guess. The fact that your older needles all look okay would also seem to say the roots are basically okay.
One year of methodical tedium and you probably will have learned more than most people do in a decade.
. It has some good potential, but it should at least provide some good experimental material as I learn. To start, I just want to see if I can get it back to some healthy looking growth. You can see in the zoomed-in photo that there are a lot of candles that have barely needled out. Being so late in the year, I'm assuming this isn't normal and that it may be the tree's reaction to losing so many branches. I'm in Michigan, so there's no chance these needles will have enough time to lengthen and harden off before it gets too cold. Should I remove these candles to help the tree conserve what energy it has? Or should I let them grow so it can recuperate what energy it can? What about the cones? Any other advice for care?
