Leaders: to side shoot or not to side shoot?

[SeanS]

Did you look at the picture I posted?

I did, but what I see is a sacrificial leader with the side branches cut off at each whorl, but many apical buds growing at the top. I already do this on my young JBPs, but only because the side shoots were shading out the lower growth so I cut off the side shoots mid summer last season. What I’d like to know is when should the side shoots be cut off? Telperion seems to leave all the top shoots growing, but then removed them at some point. When? Only at the start of the next season? Which would mean they were all allowed to grow the previous season?

currenty
I have 4-6 candles extending at the top of my young JPB sacrifice leaders. Do I let them all grow this spring and only reduce them later one if they shade out the bottom growth or possibly only at the end

 

[SeanS]

No, you have it wrong. Go back and LOOK at the pictures I posted. Those sacrifice branches are 15 feet tall! Each year they went and removed the side shoots of the sacrifice at the beginning of the growing season, leaving only the central leader. That picture was taken in late summer. The only side shoots on that sacrifice trunk are the current season’s growth.

That strong central leader produces a hormone that signals all the cambium between itself and the roots to build wood to support it. It’s the hormone, not the leaves, that build wood.

My established bonsai have lots of leaves, but because there’s no strong central leader, there’s no hormone produced (or very, very little). Therefore, no trunk thickening occurs! (Or very, very little).

Thank you, this response answered my previous question

 

[SeanS]

Only keep the central leader, as Adair showed in his photos. Especially on JBP. Build the trunk one section at a time, leaving small side shoots and keeping them short for use later. Let the trunk run, prune back that sacrifice branch to only a leader, and strip needles in the fall so they’re only at the top. This keeps those small shoots below stronger. When you have achieved the desired trunk section, chop it back and build the next section the same way.

So cut the side shoots off each whorl at the beginning of each season like Adair says?
I’m aware of keeping lower growth healthy and not shading it out. I just want to know how to actually grow the leader in the most effective way

 

[JeffS73]

Jonas' bonsaitonight.com is a great website to study sacrifice branches, there's a lot of variation depending on things like the age of the tree, style, health and climate. I don't think you can cookie cutter an answer for this.

For example, some my pines were suffering from needle blight, so I kept as much healthy foliage as possible. Now they've had a good vigourous Summer I feel confident cutting back whorl branches to get more light to the lower branches and buds in prep for Spring.

I remember in the comments on bonsaitonight Jonas said he keeps the leader and a 'spare' which seems like a sensible minimum to me, accidents happen. I also keep some smaller side branches at the whorl if I want to graft or practice grafting in the Spring.

 

[Brian Van Fleet]

So cut the side shoots off each whorl at the beginning of each season like Adair says?
I’m aware of keeping lower growth healthy and not shading it out. I just want to know how to actually grow the leader in the most effective way

Yes. The same guy who did that work Adair always shows of those pines at Telperion is the same guy who taught me, @garywood. He’s a plant physiology genius.

 

[Adair M]

I'm not sure how I'm "wrong." I'm not being argumentative here... so please take this post as honest questioning designed to clarify and understand.

I said: "More leaves, buds, and tips = more auxin = faster growth."

Is that not true?

I asked: "Is there is anything gained by having the active leaves and buds on a sacrificial leader farther from the roots? That is, does the distance that hormones and water have to travel change anything in the growth equation?" To simplify:

Is more auxin, water movement, and growth/thickening generated from:

1. a 3-foot tall sacrificial shoot with 10 leaves at the top
2. a 20-foot tall sacrificial shoot with no side branches and 10 leaves at the top
3. a 20-foot tall sacrificial shoot with all of its side branches and 1000 leaves

This was the original question (I think). I don't think anyone is questioning your pictures or the sacrifice branch having an effect - just asking WHY leaving such a tall leader with NO side branches is better for growth, than leaving them all on it (provided they don't shade out lower non-sacrificial ones).

You're saying #2 above generates the most trunk development. Some of us are asking, why not #3.

Again, you have it wrong about the amount of foliage.

The apical growing tip produces a hormone that signals wood development to support its height. I don’t believe it’s auxin. It’s another hormone. That top apical tip is racing for the sky. Trees have evolved to grow trunks differently than side branches. I have no idea how the tree figures out which of the apical tips is THE dominant one, but they do. It starts producing the “wood” hormone, and it travels down from the tip down to the roots. Essentially, it travels down the trunk. And the cambium on the trunk responds by building more wood type cells.

Side branches don’t do this.

My pictures of my Spruce show that the trunk up near the apex has nearly a one inch diameter trunk. But, look at the picture of the whole tree, and if you look up there at the apex area, you can see it’s really rather sparce. Very little foliage. So, it’s NOT foliage that causes the thickening or building of wood. It’s something else: a hormone. That hormone is causing the tree to invest energy into building a trunk to support that growing tip top bud. Sure, that energy has to come from foliage somewhere, but it doesn’t have to be from the surrounding area.

This concept of using sacrifice branches to build a trunk is important to understand. Many people try to use lower branches to fatten the base of the trunk. And let the branch grow out to the side. On trees, like pines, which are very apically dominant, this doesn’t really work, you might get a long branch, but not much thickening. If you can stake that branch up to where it becomes the tallest part of the tree, THEN it assumes role of being the dominant bud, and IT will start producing the “wood” hormone.

Trees like maples that are less apically dominant, will thicken more uniformly. But even those develop better by using apical sacrifice trunks, and develop taper by growing out, removing the sacrifice, choosing a replacement and letting it grow out, removing it a little higher up, choosing a replacement, and on and on.

 

[Brian Van Fleet]

Broadly speaking, Auxin builds up in strong shoot tips and is an inhibitor to growth behind it. When the strong shoot is removed, the auxin is reduced, so other branches below the cut are no longer inhibited. Cytokinin is the hormone associated to cell division and shoot growth.