Defoliation 101

[markyscott]

Wait, what?! Damn it! Now you tell me. Why didn’t someone tell me sooner... *goes outside to work on trees*.
And here I’ve also been watering my trees frequently, like some kinda fool. Can finally stop wasting water..

But, seriously, great thread, great read . It should be of no consequence but I’m doing similar actions to a Acer P “Beni Maiko”, and a European hornbeam at the moment. Not as experiment, as just normal and best practice. But I’m taking pics, if they can be of any use. Awaiting response from them currently.

Also perhaps more useful, my other Acer P, on some large sacrifice branches left to grow, unpruned or defoliated, started to push a second flush of growth. As far as I see it, this is just purely out of good vigour and strength. So It shows that you may even see this second flush, whether you prune, defoliate, or do nothing. Always loads of variables at play!
But as a very simplified statement, I completely agree with you. And overall I think it’s better for the complete health of the tree, to partially defoliate or leaf prune, to allow air and light in to the trees inner structure.

Thank you CD - I’m glad you got something out of it!

- S

 

[PieterVE]

I have a trident maple with fairly well developed branches and I’m trying to reduce the length of the internodes to create dense ramification.

This describes a tree in what I call refinement and I typically perform a combination of techniques. When you have the basic branch structure in place, you can start to move on to this stage of development. Trident maples are pretty robust, especially when you’re fertilizing aggressively and you’re in a warmer climate. They’ll stand up to some pretty aggressive techniques. I let that first stage of growth flush out and the new shoots begin to extend. In the early stages of refinement, I let them extend more - later, I don’t let them extend as much so as to avoid coarse growth at the end of the branches. I generally avoid fertilizing during the fist flush of growth. You’ll just get really long internodes that you can’t use. I go through every extending shoot on the tree. If the internode is short enough, I cut back and defoliate at the same time. If it’s not, I cut back all the way to the base of the shoot. Here’s an example.
View attachment 304497 View attachment 304498 View attachment 304501

See? The first internode is too long to use. So I cut back all the way to the first set of leaves. I shoot pruned and defoliated at the same time. Hopefully that second flush will produce a shorter internode that I can keep. If it WAS short enough, I would have cut back to the first node and left it at that. In my climate, I can do this three or four times a year on a healthy trident.

I only do this on the outer canopy where the growth is very strong. Where it is medium strength, I shoot prune, but I don’t defoliate, but I might leaf thin. I may even cut the leaves in half. On the weakest growth, I just leave it alone.

After a few weeks, you’ll get another flush of growth - where there was one shoot, there will be two.

View attachment 304504 View attachment 304505

Scott

Great tread Scott, thank you so much for the information you give !

Sorry to get back to this, but after you get this second flush of growth, when do you prune again ? In summer, or after there are 8 pair of leaves or ... ?

Grtz Pieter

 

[William N. Valavanis]

Spring arrives a bit later in Rochester, New York, than other parts of the world. On Monday Diane Koretz, a member of my Monday Senior Crew defoliated my Katsura Japanese maple bonsai. I've learned during the past 50 odd years that Japanese maple cultivars differ how they develop twig ramifications and respond to defoliation. Here is the latest development of a Katsura Japanese maple bonsai. Spring 2020 was not a good year for the typical bright coloring of Katsura.

May 2014

May 2020

June 2020 before defoliation

June 2020, after defoliation

June 2020, after trimming, now I see several heavy branches which should be eliminated

 

[markyscott]

Great tread Scott, thank you so much for the information you give !

Sorry to get back to this, but after you get this second flush of growth, when do you prune again ? In summer, or after there are 8 pair of leaves or ... ?

Grtz Pieter

Thanks PieterVE. For me, I guess I try and read the tree and think about what I’m trying to accomplish. Basically, when it looks like this:



It’s time to work. What I prune, how much I prune, what I defoliate, how much I defoliate, etc, are all dependent on the species and on what I’m trying to accomplish. If basic branch development is what I’m after, I let the branches grow significantly. I wire them into place, focusing on the angle the branches exit the trunk. I do not cut the growing tips. I only remove the older leaves on the strongly extending shoots in order to let light into the interior. A trident at this stage looks like this when I’m done.


If the tree was in refinement, it would look completely different after the work. So I’d encourage you to focus on two things. Read the tree to focus on when it’s ready for work. Then consider what you’re trying to accomplish with the tree. That will tell you a lot about what to do and when to do it.

One problem that holds a lot of people back is they start focusing on refinement before their basic branch structure is in place. I see that a lot - even in people on this site that consider themselves “advanced”. They end up with lots of twiggy growth on poorly developed, young-looking branches. So many examples of this here. So I guess the third thing is to study what a well-developed branch looks like so you know what you’re shooting for and when you can start to adapt your technique for the next stage of development.

Hope that helps
Scott

 

[markyscott]

Spring arrives a bit later in Rochester, New York, than other parts of the world. On Monday Diane Koretz, a member of my Monday Senior Crew defoliated my Katsura Japanese maple bonsai. I've learned during the past 50 odd years that Japanese maple cultivars differ how they develop twig ramifications and respond to defoliation. Here is the latest development of a Katsura Japanese maple bonsai. Spring 2020 was not a good year for the typical bright coloring of Katsura.
View attachment 307948
May 2014
View attachment 307949View attachment 307949
May 2020
View attachment 307950
June 2020 before defoliation
View attachment 307954
June 2020, after defoliation
View attachment 307955
June 2020, after trimming, now I see several heavy branches which should be eliminated

Thank you Bill - beautiful tree. I see that you removed all the foliage. I’m sure there is a lesson in here for those of us trying to learn. With respect, can you please explain why you might remove the foliage from the weak interior shoots as part of this work? I always try and maintain the foliage on interior shoots to strengthen them when I remove the outer canopy. Can you discuss more about what the practice of removing the foliage on weak interior shoots does that furthers the development of this tree?

Thank you

Scott

 

[River's Edge]

I deliberately tried a variation in technique by branch and by plants! Three Prunus Mume as mentioned earlier in this thread. Here is the result! The plant where the apical leader was left intact responded on the lower branches with a few strong side shoots. The plants where the apical leader was also treated with leaf removal and cut back responded with increased number of side shoots and smaller leaves. I did leave some older leaves for comparison, they stand out. This is three weeks later.
I think it is important to note that branches can be treated independently in Mume to create side shoots while retaining extension growth in other areas.

 

[William N. Valavanis]

Check out my newest blog on defoliating two Japanese maple bonsai. Both bonsai and garden tree are my 40 year cuttings.
www.valavanisbonsaiblog.com

 

[markyscott]

Check out my newest blog on defoliating two Japanese maple bonsai. Both bonsai and garden tree are my 40 year cuttings.
www.valavanisbonsaiblog.com
View attachment 308080

Thank you Bill - I read your blog posting with great interest. I think that I saw you comment about the two maples on your facebook live video. I now have even more appreciation for my visit to your garden. Hopefully, I’ll get to do it again this autumn.

- Scott

 

[Arcto]

This is the kind of thread that is the main reason I joined bnut. Great job Scott! Keep em coming. Carry on.

 

[PieterVE]

Thanks PieterVE. For me, I guess I try and read the tree and think about what I’m trying to accomplish. Basically, when it looks like this:

View attachment 307946

It’s time to work. What I prune, how much I prune, what I defoliate, how much I defoliate, etc, are all dependent on the species and on what I’m trying to accomplish. If basic branch development is what I’m after, I let the branches grow significantly. I wire them into place, focusing on the angle the branches exit the trunk. I do not cut the growing tips. I only remove the older leaves on the strongly extending shoots in order to let light into the interior. A trident at this stage looks like this when I’m done.
View attachment 307947

If the tree was in refinement, it would look completely different after the work. So I’d encourage you to focus on two things. Read the tree to focus on when it’s ready for work. Then consider what you’re trying to accomplish with the tree. That will tell you a lot about what to do and when to do it.

One problem that holds a lot of people back is they start focusing on refinement before their basic branch structure is in place. I see that a lot - even in people on this site that consider themselves “advanced”. They end up with lots of twiggy growth on poorly developed, young-looking branches. So many examples of this here. So I guess the third thing is to study what a well-developed branch looks like so you know what you’re shooting for and when you can start to adapt your technique for the next stage of development.

Hope that helps
Scott

Yes, very helpfull !

 

[Brian Van Fleet]

I used to fully defoliate this Japanese Maple, but it always seemed to weaken the tree. It would shed some small interior branches, and concentrate growth on the exterior...basically the opposite of what I was trying to accomplish. About 8 years ago, I changed tactics and began to do a partial defoliation, removing one of each pair of leaves toward the end of May. This seemed to help encourage more interior buds.

Last winter, I heavily pruned the tree, and wired it. Due to this, I also decided to not repot this year; an otherwise annual task for over 15 years. The results of partial defoliation were magnified this year.

Late May, before work (yes, it suffered some unfortunate dieback in the right side...more on next week’s blog post):

Unwired:

Partially Defoliated, some shoots rewired:


It always looks a little windblown for a few days until the leaves reorient themselves. Then it starts to look normal again.


And 3 weeks later, new growth is really taking off in the interior of the tree, easily seen because of the bright red color:

I will let it extend another couple weeks, and then wire some of the new shoots into position. A shot of the interior:

 

[Gary McCarthy]

I used to fully defoliate this Japanese Maple, but it always seemed to weaken the tree. It would shed some small interior branches, and concentrate growth on the exterior...basically the opposite of what I was trying to accomplish. About 8 years ago, I changed tactics and began to do a partial defoliation, removing one of each pair of leaves toward the end of May. This seemed to help encourage more interior buds.

Last winter, I heavily pruned the tree, and wired it. Due to this, I also decided to not repot this year; an otherwise annual task for over 15 years. The results of partial defoliation were magnified this year.

Late May, before work (yes, it suffered some unfortunate dieback in the right side...more on next week’s blog post):
View attachment 309036
Unwired:
View attachment 309042
Partially Defoliated, some shoots rewired:
View attachment 309038

It always looks a little windblown for a few days until the leaves reorient themselves. Then it starts to look normal again.
View attachment 309039

And 3 weeks later, new growth is really taking off in the interior of the tree, easily seen because of the bright red color:
View attachment 309041
I will let it extend another couple weeks, and then wire some of the new shoots into position. A shot of the interior:
View attachment 309040

I really like the look of the tree with the new red growth and the older green leaves. You should strive for that

Question on your partial defoliation method. Do you ever also cut back the leaves you are leaving on the tree? Or are you always just removing the full leaf?

 

[AlainK]

I've always found 'Orange Dream' to be one of the most prone maple for leaf spot. This year, the one I kept in a bonsai pot (an air-layer) in almost full sun didn't show any sign of these, until two weeks ago, when we had heavy rain. From the side and under artifial light in the basement, it doesn't look as obvious as outside, from above. The "mother-tree" is in the shade and has no sign of leaf spot.

So, I defoliated the little one 2 days ago.



On the left of the big one (May, and today), 'Phoenix'.

 

[markyscott]

I've always found 'Orange Dream' to be one of the most prone maple for leaf spot. This year, the one I kept in a bonsai pot (an air-layer) in almost full sun didn't show any sign of these, until two weeks ago, when we had heavy rain. From the side and under artifial light in the basement, it doesn't look as obvious as outside, from above. The "mother-tree" is in the shade and has no sign of leaf spot.

So, I defoliated the little one 2 days ago.

View attachment 309110 View attachment 309111 View attachment 309112

On the left of the big one (May, and today), 'Phoenix'.

View attachment 309113 View attachment 309114

What were you trying to accomplish by defoliating this tree? We’re you trying to eliminate the leaf spot?

- S

 

[AlainK]

Actually, the leaves were quite big for the overall "design" and I had defoliation in mind to try and reduce the size of the leaves.

When I saw that the tre tree had leaf-spot, I thought it could be a double care, first for the size of the leaves, and when the petiole start to fall when you touch them, a little spray of copper and/or sufur-based treatment. It's in fact to "accidental defoliation", when a tree gets sunburnt. And it's usually a good opportunity to trim branches. Here's an example :



Or this Acer buergerianum from seed in a very small pot, all the leaves were dry, so I put it in the shade, and 10 days later, it shows new leaves.

 

[Brian Van Fleet]

I really like the look of the tree with the new red growth and the older green leaves. You should strive for that

Question on your partial defoliation method. Do you ever also cut back the leaves you are leaving on the tree? Or are you always just removing the full leaf?

Usually just leave the remaining leaf intact.

 

[AlainK]

I just go the whole hog.

 

[markyscott]

I just go the whole hog.

That’s clear. Personally, I wouldn’t remove any leaves on trees like this in early development when my main goals would be building trunk, nebari and primary branch structure. I’m sure your tree will leaf out again, but by my way of thinking, deferring those main developmental goals by slowing down the tree in order to reduce leaf size seems like putting the cart before the horse. If you‘re ever dissatisfied with the progress your trees are making, perhaps you’ll think back on this thread and recognize that there might be an alternative approach.

S

 

[leatherback]

One problem that holds a lot of people back is they start focusing on refinement before their basic branch structure is in place. I see that a lot - even in people on this site that consider themselves “advanced”. They end up with lots of twiggy growth on poorly developed, young-looking branches.

This might be the most important comment I have come across on this website. 200% agree, even though I am not sure of the route myself most of the time, lol

new growth is really taking off in the interior of the tree, easily seen because of the bright red color:

yes!

 

[AlainK]

putting the cart before the horse

We have a similar expression in French "Mettre la charrue avant les boeufs" ("boeufs" = "oxen")

But once again, these were "accidental", or "emergency" defoliations.

I'll keep you updated so we can continue this conversation.