Defoliating.. So many contradictions

[Scooter_M]

Hey guys, I may be a victim of over researching, but I'm watching a lecture on YouTube called 'bonsai trees best lecture to learn from' and there's a part about ramification. I've always known ramification to be cutting back the branch, and forcing a fork to occur, however in this lecture he talks about defoliating forces the buds at the base of the leaves to shoot out giving new growth. He talks about leaf size and how much light the tree needs which all makes sense to me. Cut of 4 big leaves, it will regrow 16 smaller ones. However my concern comes in around the defoliating, I've heard a lot of people say that defoliating isn't good for some trees, and some people say it's an our right no no. So my main question is, how do you guys get ur ramification? Defoliation or cutting back? And on which species?

[kcpoole]

who made the video? an unknown punter or someone with credibility and a track record?

Back to the Question.
Defoliation will cause every node to force new leaves but no new branching. It will develop smaller leaves, but will not produce more leaves per se.

Cutting back will force New shoots to develop, and on most trees you cut back 1 branch and will then get 2 or more new shoots. This is Ramification where a single branch becomes 2 smaller branches. Cut back the 2 new branches and you will get 4 more new ones, Cut those back you get 8 new ones.

Ken

[Guy]

this could be the video referred to.
https://www.youtube.com/watch?v=JXsy6eiPAgE

[Scooter_M]

Yep that's the video. He's quite specific that defoliation will give new branches, I don't usually search for well known lectures or anything, all information is handy.

Thanks kc, what u described was my understanding of ramification. It was just different to hear a defoliating version.

[CraigM]

Had the same confusion / contradiction when it came to a beech, partial defoliation worked well for me. If interested, you can view the thread viewtopic.php?f=129&t=19211.

[Scooter_M]

Good result there Craig, did it result in only leaves, or did you actually get new branches from the defoliation?

[63pmp]

What species of tree are you talking about defoliating?

And what stage of development is it in?

Paul

[treeman]

It's probably easier to list which trees should not be defoliated rather than which ones can be. There are not many healthy young trees which don't respond to it. I'll leave the list to others. But I will note that I have found you get more even re-growth after defoliation if you cut the branch tip off as well. The timing is also important. Leaves should be well matured and the tree ready to start it's next flush of growth. (often one month after a good feed)

[Scooter_M]

Hey 64pmp, well that question is what i'm starting to think is the key here, the video suggests its pretty much a blanket rule that defoliating will cause extra branching, he talks about there being a max "light receptor" size. His theory is basically this:

Tree's have a maximum number of light receiving surface area (leaves), to support its roots and max overall tree size.

A very large tree might have 10 leaves, 1 square foot of receptive area. Making up a total of 10 square feet of surface, for arguments sake, this is the maximum size this particular tree can support, 100%.

If you take off those 10 leaves, it produces smaller leaves, but because the leaves are small, it needs to make more of them, so instead of 10, 1 foot leaves, you have 100, 0.1 foot leaves. To support these 100 leaves, it now needs to sprout branches to hold them all.

Defoliate again, and you'll get 1000 0.01 foot leaves, and of course more branches to hold them. etc etc.. Now of course it wouldn't be as clean as multiples of 10's, but you get the theory.

Now this to me, for a theory, makes perfect sense. It qualifies why a try has a certain growing height in nature, a combination of the ability to absorb light, strength and size of roots for nutrients and water, the internal mechanics of the tree to get nutrients all the way around the trunk and to the tips of each branch. It makes sense there is a limit to this. By defoliating against this theory your forcing the tree to grow lots and lots of small branches to compensate and gather enough light to support the tree.

But after all this, its just one guys theory, and although it makes sense to me, i've never heard anyone else say defoliating causes new branches, and it seems the more people that reply on here, seems to solidify that.

[63pmp]

Hi Scooter,

I don't subscribe to his theory that "light receptors", what ever they are, are responsible for leaf size.

I do know that different species responds differently to defoliation. Figs definitely respond well to defoliation.

My understanding is that, type of species, hormonal effects and stored/available nutrients impact on how the plant responds. The plant does not calculate the amount of leaf surface area required and available buds, and then determine leaf size in relation to that.

However, leaf size will depend upon the amount of N available to the plant to produce new leaves, this is why plants that are over fed with N develop large leaves compared to underfed plants. The amount of buds that develop will depend on the vigor of the tree prior to defoliation.

Paul

[treeman]

Hi Scooter,

I don't subscribe to his theory that "light receptors", what ever they are, are responsible for leaf size.

I do know that different species responds differently to defoliation. Figs definitely respond well to defoliation.

My understanding is that, type of species, hormonal effects and stored/available nutrients impact on how the plant responds. The plant does not calculate the amount of leaf surface area required and available buds, and then determine leaf size in relation to that.

However, leaf size will depend upon the amount of N available to the plant to produce new leaves, this is why plants that are over fed with N develop large leaves compared to underfed plants. The amount of buds that develop will depend on the vigor of the tree prior to defoliation.

Paul

I agree with that.
Basically, the tip of each branch (leaf) releases an inhibiting hormone down the branch which keeps the lower buds retarded or dormant. ( If it was not there, there would be complete chaos and the tree could not grow correctly) So by removing the tip of the branch (or defoliating) we also remove production the the inhibiting hormone (or stimulate prodution of growth hormone) and the secondary buds then spring into life.
With defoliation, Because we are not just pruning branch tips but removing ALL leaves, we free ALL the dormant buds from the chemical inhibition and they can then all sprout. But because there are so many moving at once the limited mineral resources held in the tree must be distributed evenly throughout and we end up with smaller leaves.

[Scooter_M]

Hi Scooter,

I don't subscribe to his theory that "light receptors", what ever they are, are responsible for leaf size.

I do know that different species responds differently to defoliation. Figs definitely respond well to defoliation.

My understanding is that, type of species, hormonal effects and stored/available nutrients impact on how the plant responds. The plant does not calculate the amount of leaf surface area required and available buds, and then determine leaf size in relation to that.

However, leaf size will depend upon the amount of N available to the plant to produce new leaves, this is why plants that are over fed with N develop large leaves compared to underfed plants. The amount of buds that develop will depend on the vigor of the tree prior to defoliation.

Paul

I agree with that.
Basically, the tip of each branch (leaf) releases an inhibiting hormone down the branch which keeps the lower buds retarded or dormant. ( If it was not there, there would be complete chaos and the tree could not grow correctly) So by removing the tip of the branch (or defoliating) we also remove production the the inhibiting hormone (or stimulate prodution of growth hormone) and the secondary buds then spring into life.
With defoliation, Because we are not just pruning branch tips but removing ALL leaves, we free ALL the dormant buds from the chemical inhibition and they can then all sprout. But because there are so many moving at once the limited mineral resources held in the tree must be distributed evenly throughout and we end up with smaller leaves.

Ahhh now theres an explanation or two! Now that makes it alot clearer. I have also heard about not all plants liking defoliation. So whats the trick with those then to reduce leaf size? Or something like an elm where it drops all it leaves in winter?

[63pmp]

.... But I will note that I have found you get more even re-growth after defoliation if you cut the branch tip off as well. The timing is also important. Leaves should be well matured and the tree ready to start it's next flush of growth. (often one month after a good feed)

Yes, I agree with you here.

There are so many techniques with defoliation, its best to just go with what the tree requires. I only use it for ramification purposes, not ever on trees developing trunks.

I fully defoliate my English elm at the end of spring/early summer and it shoots back with smaller leaves and shorter nodes, but it also exhausts the poor thing and I only get 5 or 6 leaves per shoot and that's it for the rest of summer.

I tend to partially defoliate Japanese maples to let light into the interior of trees, if I defoliate at all. Tridents respond well to defoliating. I don't defoliate hornbeam, beech or azalea. Box are weird as you must leave a pair of leaves at the ends of the shoot to keep sap flowing.

Don't have any tropicals ...

Hope this helps; learn as many techniques as you can so you can pick and choose the best options when needed.

The best videos on youtube for consistent and excellent bonsai technique are Bjorn Borvalis's.

Paul

[63pmp]

Don't forget, tip pruning and shoot pruning are also very important in developing ramification. Not just defoliation.

Paul

[Scooter_M]

Cheers 63, with the you tube, did you mea Bjorn Bjorholm ? cant find the one you mentioned.