[IBC] unrestrained top growth
Lynn,
Unrestrained top growth should do the trick for all trees that I have worked with. Can't think of one that did not work that way. Jerry Meislik Hmmmm. That's a tough one. Obviously, the more foliage, the more transpiration, and the easier to overwhelm a weak root system. However, if you put the tree in a high-humidity tent, which would minimize transpiration, would greater foliage improve root growth? There would be more energy available for growth, but as I explained a couple weeks ago, sugar is moved in plants using a "source-sink" mechanism, so sugar won't move to where a potential root *ought* to be, only to a new, actively growing root. Besides, some research shows that high sugar concentration inhibits lateral root development. And how do you get root initiation? By the action of hormones. Auxin, produced by apical meristems of shoots stimulates lateral root growth. So if you prune the top growth, you will temporarily be reducing auxin, although as soon as back-budding occurs, and all the new branches begin to grow, the amount of auxin will be increased. So a tree that buds back quickly and easily would probably produce new roots rapidly, too. However, if a tree was in real trouble, it might be better to leave the strong apical meristems in place. I don't know; I'm afraid I'd be stuck with trial and error. -- Nina Shishkoff Frederick, MD ************************************************** ****************************** ++++Sponsored, in part, by Mike Page ++++ ************************************************** ****************************** -- The IBC HOME PAGE & FAQ: http://www.internetbonsaiclub.org/ -- +++++ Questions? Help? e-mail +++++ |
[IBC] unrestrained top growth
Thanks to you all, Alan for giving me cause to actually think
;) and Jerry, Jim and Dale and Nina for helping the gears work. I will have to figure my chances but I have some good thinking experience behind my judgments now. Previously I didn't much hesitate. Lynn ---------------------------------- From Dr. Nina: Lynn, Unrestrained top growth should do the trick for all trees that I have worked with. Can't think of one that did not work that way. Jerry Meislik Hmmmm. That's a tough one. Obviously, the more foliage, the more transpiration, and the easier to overwhelm a weak root system. However, if you put the tree in a high-humidity tent, which would minimize transpiration, would greater foliage improve root growth? There would be more energy available for growth, but as I explained a couple weeks ago, sugar is moved in plants using a "source-sink" mechanism, so sugar won't move to where a potential root *ought* to be, only to a new, actively growing root. Besides, some research shows that high sugar concentration inhibits lateral root development. And how do you get root initiation? By the action of hormones. Auxin, produced by apical meristems of shoots stimulates lateral root growth. So if you prune the top growth, you will temporarily be reducing auxin, although as soon as back-budding occurs, and all the new branches begin to grow, the amount of auxin will be increased. So a tree that buds back quickly and easily would probably produce new roots rapidly, too. However, if a tree was in real trouble, it might be better to leave the strong apical meristems in place. I don't know; I'm afraid I'd be stuck with trial and error. -- Nina Shishkoff Frederick, MD ************************************************** ************ ****************** ++++Sponsored, in part, by Mike Page ++++ ************************************************** ************ ****************** -- The IBC HOME PAGE & FAQ: http://www.internetbonsaiclub.org/ -- +++++ Questions? Help? e-mail +++++ ************************************************** ****************************** ++++Sponsored, in part, by Mike Page ++++ ************************************************** ****************************** -- The IBC HOME PAGE & FAQ: http://www.internetbonsaiclub.org/ -- +++++ Questions? Help? e-mail +++++ |
[IBC] unrestrained top growth
At 08:32 AM 6/16/03 -0400, Nina Shishkoff wrote:
Lynn, Unrestrained top growth should do the trick for all trees that I have worked with. Can't think of one that did not work that way. Jerry Meislik Hmmmm. That's a tough one. Obviously, the more foliage, the more transpiration, and the easier to overwhelm a weak root system. However, if you put the tree in a high-humidity tent, which would minimize transpiration, would greater foliage improve root growth? There would be more energy available for growth, but as I explained a couple weeks ago, sugar is moved in plants using a "source-sink" mechanism, so sugar won't move to where a potential root *ought* to be, only to a new, actively growing root. Besides, some research shows that high sugar concentration inhibits lateral root development. And how do you get root initiation? By the action of hormones. Auxin, produced by apical meristems of shoots stimulates lateral root growth. So if you prune the top growth, you will temporarily be reducing auxin, although as soon as back-budding occurs, and all the new branches begin to grow, the amount of auxin will be increased. So a tree that buds back quickly and easily would probably produce new roots rapidly, too. However, if a tree was in real trouble, it might be better to leave the strong apical meristems in place. I don't know; I'm afraid I'd be stuck with trial and error. Nina, et al I have spent years closely studying the response of plants to pruning. Your instincts are correct, leave meristem growth to quickly rebuild a new root system. I have written several articles about this effect at my website, one of them is Pruning Bareroot Seedlings. I have even done comparison studies on establishing Acer palmatum var atropurpureum plugs into my 2 3/4 inch pots. I divided 100 plants, half were top pruned (this was early summer) and the other half were not pruned at all upon shifting them from plugs to pots. They were placed side by side in the shade. By the end of summer, the unpruned ones were completely root established and pushing new growth, the top pruned ones were just sulking. By the way, at that time I thought the opposite would happen! That was probably eight or ten years ago. Since then, I have paid very close attention to balancing growth and transpiration so that I could maintain maximum terminal growth. That is the key, maintaining water balance. In winter, it's easy, especially for deciduous plants. You can start enormous plants with practically no root system. We do it all the time with bareroot fruit and ornamental landscape trees. Bonsai and other container plants are no exception. The very long period of low or no transpiration coupled with cool moist conditions allows you to leave maximum meristem growth. Pruning only delays the response and pushes you farther into hot weather. I have got this process down to where I lose very few plants now. I get two or three year old bareroot seedlings and cut off 2/3 or more of the roots in order to get them in my 2 3/4 inch pots. the tops are sometimes two feet tall. By about this time, they are beginning to push new growth and have nearly filled the pots with roots. Summer is more difficult because the transpiration is very high and it must be limited in some fashion. I find that removing foliage is superior to actual pruning, which removes the meristem and delays the growth response. Bud break following leaf removal is quite fast and results in a large area of leaf surface restored in a very short time. Knowing how much foliage to remove and how much protection to give a plant in summer just takes experience, there is no way around it. I am still actively repotting small and one gallon plants that are in collapsed soil mix with very poor root systems. Fortunately, the weak roots have already limited the amount of foliage so little to no pruning is required when they are placed under shade cloth and given some extra watering when it is very hot. One area that is still testing my powers is conifers. These guys just don't like summer repotting. I have just about learned their limits but I still get caught. This year I am losing about a half dozen nice white pines because I repotted too late and didn't give them enough protection. I knew I was pushing the envelope, but I was afraid they would not survive anyhow without repotting. I still think I could have saved them if I had the proper facilities, but the new nursery isn't that far along yet. What they need is grafting house conditions, where both temperature and humidity can be controlled summer and winter, usually cooler than regular greenhouse conditions. If you want to generate new roots, general heading back of plants is not the way to limit transpiration. Prune methodically, remove unwanted branches, and that isn't enough remove foliage, but maintain those terminal buds. You can correct any aesthetic problems later, after the plant is established. Brent in Northern California Evergreen Gardenworks USDA Zone 8 Sunset Zone 14 http://www.EvergreenGardenworks.com ************************************************** ****************************** ++++Sponsored, in part, by Mike Page ++++ ************************************************** ****************************** -- The IBC HOME PAGE & FAQ: http://www.internetbonsaiclub.org/ -- +++++ Questions? Help? e-mail +++++ |
[IBC] unrestrained top growth
Folks
I sent this message to Theo, who asked for a private reply, but since it bounced at his address, I am just going to post it here. Brent Theo Sorry, this is so late, things are a little busy around here. See comments below: At 09:22 AM 6/19/03 +0200, you wrote: HI My maple has been repotted in beginning of April and probably I cut too much roots and washed too much the root ball and made a new mix that is very drying with leaf mould sand and akadama Yes, I try to limit or completely avoid root pruning when repotting during the growing season. Washing out all the old soil isn't a bad practice IF, it comes out easily, the roots are not disturbed, and you don't do it too vigorously. I 'irrigate' tighter rootballs. I just keep watering and watering until the water stops coming out muddy and starts to get clear. The remaining soil particles are large enough to stay and much new porosity is added to the remaining root ball, so you get your drainage back. I then just backfill the voids with new soil. I am still doing this even at this late date, but the aftercare is important. They must not be heat stressed afterward, shade, a lot water, humidity, and cool conditions should be provided. Since than has pushed out the first pair of leaves as usual and since over 2 months no growth all is static the leaves are ok but no elongation on twigs no new eyes opening back in the trunk or branches .. just very few that do not burst out .. all is just static! That's because it is trying to regenerate the roots. What happens is that the compromised root system does not have the leaf stimulus (hormone) to promote new shoot forming hormones, so the leaves that open from stored tissue carbohydrates open but don't grow. They will keep feeding the roots until the roots are strong enough to begin growing again. When this happens, then the roots will once again begin sending the shoot hormones and top growth will start. When you prune both top and roots at the same time, you really create havoc with this system. That's why I always advocate doing one or the other but not both root and top pruning at the same time. It is a 20 years old 80 cmt straight Deshojojo jap maple I fertilized regularly with mild fertilizer almost every other day but nothing happens I do not dare cutting leaves as has been repotted this year shoulk'd I defoliate just a part of them to provoke growth ? Older trees will have even more trouble getting the system working again because they lack the vigor of more juvenile growth. Do NOT prune under any circumstances or you will just create a bigger problem. The roots need that leaf stimulus. I am perplexed ! thanks for your feed back Theo All you can do is wait. New growth may come very late in the season, which means that it will be quite soft going into winter. So the next drama will be protecting it from fall freezing weather. You want it to grow as long as possible to gather strength, but doing so sets it up for damaging freezes. You should provide a place (outdoors, not in the house) where it will stay between about 28F and 40F (-2 to +5C) for the winter. It is important that it be cold so it will go dormant, but not too cold to avoid root damage. Brent in Northern California Evergreen Gardenworks USDA Zone 8 Sunset Zone 14 http://www.EvergreenGardenworks.com ************************************************** ****************************** ++++Sponsored, in part, by Mike Page ++++ ************************************************** ****************************** -- The IBC HOME PAGE & FAQ: http://www.internetbonsaiclub.org/ -- +++++ Questions? Help? e-mail +++++ |
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