Hard Pruning Pines

I have a question about the mechanics of Pine physiology. It is well understood that hard pruning of pines should be done in the Winter when the tree is growing less and sap leakage will be minimised.

But I am curious and want to understand why is it that even when we choose the correct time to hard prune a pine we can not reduce the trees foliage by too much.

I am only starting to learn about pines as the deciduous are my first love and I am curious what is the actual mechanics behind the tree keeling over if we take too much off?

Is it something to do with the tree not having the foliage to draw up water?

Would the same thing happen if you did not cut of any large branches but just stripped bare 1/2 to 3/4 of the foliage?
Just curious
Thanks for any help

A big question Brett with no straightforward answer.

Methods for pruning pines tend to be species specific and also different seasons and reasons for different species.

You can happily cut off more than half a shoot on a Scots Pine (sylvestris) or a black pine (thunbergii) and they will bud back further down the branch towards the trunk.

This would, possibly kill a 5 needle pine branch if done at the wrong time.

If you can be a bit more specific I'm sure will you will get more info than you bargained for



TimR

Tim is quite right, you need to be a bit more specific. I for one never prune my pines in the winter but all my pines are Scots and they bud back very well if pruned at the end of July. Which variety are you talking about.

Ok thanks guys I will try to be more specific.
As I said I am only learning with Pines I have mainly JBP also a dwarf scotts pine and a radiata.
So lets keep it simple and talk about JBP.
I recently picked up a young Pinus Thunbergiana Kotobuki with the plan to make a literati out of it. We have a workshop/contest on literati over on our Aussie site ausbonsai.com that goes for a year.
Now not being one experienced with Pines I started to experiment pruning it to see how much sap was lost and how much I could remove. This is in Spring here. I found that there was not excessive sap loss on the small branches but I did not think I could remove the top of the tree without excessive sap loss so I figured I could strip the top off needles which would direct the growth where I wanted it without actually removing the top of the trunk.
I almost heard the tree scream as I started plucking at least 80% of it's very healthy foliage off. Then I wrapped and bent some movement into the trunk. I and others where concerned that I had removed too much foliage in one go and the tree would suffer.
So far so good over two weeks later the tree is sucking up water and may look even slightly more vibrant. I think it is the youth and health of the tree that let me get away with it.
Since then I have wondered what is the actual mechanics of a tree dieing from such treatment. Is sap loss the only issue or is there something about the foliage needed to draw a certain amount of water.
One theory put forward is that the tree withdraws sap too far and dies?

Say you wanted to reduce an old JBP by half or more. Could you just strip the top half of foliage and wait to remove the dead half later. If you do chop the tree in half at whatever the best time of the year is why is it that the tree could die? What physiological damage occurs that kills the rest of the tree?

Thanks for any help
I can't work out how to load pics at the moment so I will just give a link to the actual work that I did on the kotobuki that sparked my curiosity.
http://www.ausbonsai.com/forum/viewtopic.php?f=122&t=2623
Oh and the contest encourages advice from outside entities so feel free to give any advice about my progression with the literati as well. The information will be passed on in the workshop/contest.

Sorry, cant help you much with Jbp. Apart from anything else, the timing is different over here. It takes 2 years to do here, what they achieve in 1 year in Japan. Looked at your forum downunder, looks vey good.

Ok can you pick a species and pose the same questions

The Aussie site has been a real treat for us. The bonsai community has become much stronger because of it.

Did you see the 360 bonsai viewing?
http://www.ausbonsai.com/forum/viewforum.php?f=112


The operator Steven should be congratulated for the promotion of Australian bonsai he has worked very hard at.
He has some new suprises comming to celebrate our first year.

No takers

Hi Brett. Sorry no one else has jumped in. You said you've got a dwarf Scot's pine. I will talk in seasons and not months as it may cause confusion.Firstly, I think you've got away with the reduction on your JBP this time but maybe a reduction over time would be more prudent. I f you had styled more of the tree to start with, you could have turned some of your work into deadwood and jin for an older convincing image maybe?
Dwarf Scotties usually bud back as well if not better than JBPs, but even so its all down to good feeding and late summer pruning. For backbudding I wait until the candles have opened and elongated.For best results cut out the whole candle and within a month, there will be new buds everywhere. This cannot be performed every year as needles only last into the third year, so in the second year reduce candles by half.
You spoke of reducing/stripping foliage off half a tree and would a pine cope with this. If healthy, yes. I would strip the bark as well. Pines can bleed a lot but im not sure they will bleed to death? They can cope with a lot of damage, rock falls etc...
Maybe some pics of trees you want to reduce wil give you more feedback.

Hi Brett
Depends on the vigor of your pine, and if you have a good fiber root system. If cuts are not too large it ok with the aformentioned. Heavier cuts go slowly --
Steve
www.matsumomiji.com

Excellent information Will.How about a bosnian pine???Pinus heldreichii That is the pine I will be collecting in the next few weeks at the nursery that I have sucessfully talked in to letting the pine and hornbeam go fully dormant b4 digging .

Sorry never have worked one of that species
Steve
matsumomiji.com

Just found out another aka for this species is pinus leucodermis.it is a 2 needle species so I wonder if I could treat it as a black or scots pine?

Probably
Steve

Mr. Brett,

Like you said, winter is the time of year of minimized sap flow on pines. As I live in a tropical country and do not have a well defined winter, I hard prune my pines and conduct shari si-diao, from december 'til february. In the tropical winter, the angle and position of the sun changes, plus the weather in the mountains (where i have my pines and tridents) sometimes drops considerably. Both the change in the sun's position and the fact that the temperature drops to the high 50's, makes it possible for me to prune considerably.

In order to minimize stress on the trees and to balance the proportions between foliage and roots, I tend to leave several long branches with needle bundles on the ends, to be cut at a later date. This extra foliage ensures a higher survival rate, as when one stylizes trees, a lot of the needles are removed to facilitate wiring and branch positioning. After three to four months, when the tree is growing strongly, I remove the sacrificial growth.

I hope this information enables you to conduct your detailed plans in pine cultivation. Should you have any further inquiries, I will do my best to answer them properly.

Kind regards,
Jose Luis

Thanks guys I have been asking around about this one and seem to have narrowed it down some.
The theory is that if you cut alot of a pine even in winter when there is reduced sap flow, that the tree continues to draw water up through the roots and it drowns the tree.
One fix for this is to also reduce the root ball of the tree and another option is to limit the water that the tree gets.
One other theory is that pines do not store enough energy to recover from this trauma. Apparently the slower growing the pine species the more chance there is of killing it. So this makes sense.
Maybe it is a combination of the two.
The advice of reducing the root ball at the same time came from one of our talented local nurserymen Leong Kwong. You can see him severely chop a Kotobuki Black Pine here.
http://www.bonsaisouth.com.au/cms3/index.php?option=com_content&view=article&id=66&Itemid=75