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If I were to prune a branch, it would interrupt the flow of auxin in the cambium and release buds below that have been held in stasis (of course there must be cyokinins in the tissues below to release the buds; i.e., the plant is actively growing). If instead I girdled the branch, I would also interrupt the flow of auxin to the tissues below and this ought to release buds in stasis just like decapitating the branch.

Am I right/wrong that girdling and pruning are equivalent in this respect (and why please)? In other words, is girdling and pruning equivalent as far as the response of the rest of the plant is concerned?

Girdling is removing a ring of bark completely around the stem. This also removed the phloem or inner bark in which sugars from photosynthesis are transported down the tree from the foliage toward the roots. This also removes nearly all of the vascular cambium through which auxin is transported from cell to cell (like a bucket brigade). However within a day or two exposed to the air any residual cambium cells desiccate and die - in effect, girdling also removes all of the cambium. The xylem (wood) remains in tact, supplying water and minerals to the portion of the branch above the girdle.

A girdle cuts off the flow of auxin to the branch just below the girdle as well as sugars from above. Pruning cuts off the flow of auxin and sugar as well. Yet many people tell me that pruning will release more buds than making a girdle. I cannot understand how this could be true. Is the effect really different? And if it is, I am very interested in an explanation of why.

  • Please can you edit your question to explain what you mean by girdling? Girdling, also known as Cincturing, is an established technique used to produce larger fruit yields. It is otherwise known as ring barking, whereby it is used to kill trees. I assume you're referring to the latter since it's effects are similar to pruning? – Nic Apr 17 '16 at 19:43
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    Ring barking only kills a tree if there is no foliage below the girdle to feed the roots – Jim Young Apr 17 '16 at 21:01
  • Who has told you that pruning makes more buds than girdling? Do they have any evidence of it, or has pruning always worked for "them"?? – Nic Apr 17 '16 at 21:11
  • Primarily some Bonsai hobbyist friends, but I've encountered an answer or two here that imply the same, or seem to. Personally I've never seen any difference between the two. So I'm just asking, not meaning to be ... – Jim Young Apr 17 '16 at 21:17
  • okay, I'm intrigued as to if there is a difference or not – Nic Apr 17 '16 at 21:19
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You might have answered it in your question - "The xylem (wood) remains in tact, supplying water and minerals to the portion of the branch above the girdle." I don't know enough plant physiology to provide a definite answer, however here's my theory.

When trees are girdled death is not instant, since the tree will "temporarily transport water and minerals from the roots to the leaves. Death occurs when the roots can no longer produce ATP and transport nutrients upwards through the xylem." - https://en.wikipedia.org/wiki/Girdling

It involves the concentration of minerals ( or [m] ) at the point where the buds develop (X). When girdled, the [m] remains constant at X. Buds are stimulated to grow by the absence of auxin. When pruned, buds are also stimulated to grow. The rate of flow of water in xylem will be lower, so [m] will decrease as the buds grow. This stresses the plant and triggers a defensive response to grow more shoots.

If it concentrations are involved, I think it may be incorrect to say more buds are produced by pruning. By pruning, the buds produced are healthy and grow bigger. The same number of buds probably grow either way.

  • Xylem is not wood. Wood is usually considered the inert stuff beneath the vascular system. Xylem and Phloem are right beneath any bark or thickened covering, very very thin, fragile in relation to the rest of the plant. One takes water and chemicals up to the leaves and the other takes the FOOD the plant itself makes to the roots for storage. Cutting the vascular system above a bud just redistributes the energy that used to take care of the growth above that bud and cut. Making more energy focused on the next bud in line. Yes pruning stimulates more buds but be careful. – stormy Apr 18 '16 at 21:49
  • ATP is broken down to ADP to make energy. I thought that photosynthesis was the main system to create energy from the sun into useable energy for the plant. What is the system that makes energy in the roots of a plant? – stormy Apr 18 '16 at 21:51
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From what I understand, they are the same but the buds should not fall off. Done this before and nothing like this has happened. I would say that it will be fine.

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Sorry but the two are extremely different. Girdling is killing the cambium all the way around a branch, trunk of a woody perennial or tree. The Cambium is an extremely thin layer just below the bark. If one cuts this layer all the way around then that is called girdling. It will kill everything that was growing above that line as the xylem and phloem the food and water lines feeding the plant are cut/damaged and will never work again.

Pruning on the other hand is doing for the plant what it already wants to do. When branches and their leaves are NOT producing for the plant using photosynthesis the plant will start killing its own branch. To prune is to understand the plant, botany and what its ideal form should be.

Pruning very very simply means getting rid of branches that cross, branches that are angled to the inside of the plant, branches that are unhealthy or injured, thinning vegetation so that the plant gets more ventilation less disease. Never prune more than 1/3 of the plant. If you are a newbie to pruning don't ever do that much. Use clean (wipe with alcohol) and sharpened blades every single time you prune and before pruning another plant. Use only by-pass pruners. Do not use anvil type (pinching) pruners. Do not coat the cuts with anything, ever. Keep the main, the largest blade of the by-pass pruners closest to the main trunk or stem when you cut. This will leave less of a stub. Any branch that is hugely smaller and out of proportion to that branch should go. Tiny thin little branches that come off a branch that is established and very thick in relation to little tiny thin branches should go. One should be able to see the main branching through the leaves. Don't mess with the 'leader' (the main branch that determines the tree's shape) on trees unless you know what you are doing. Trees should be THINNED, shrubs should be headed and not viseversa unless you know what you are doing. Heading is trimming the ends of all branches. Thinning is pruning entire branches off from the main branch and/or trunk. If your trees/shrubs are planted too low in the soil so that the trunk with bark is below the soil or below the mulch or below the decorative rock you will be girdling and killing it. Bark on the trunk should be out of the soil and have nothing that will hold the moisture next to the bark. Just below the soil the roots will take off. There is a line between the 'bark' and the 'roots'. If one buries the trunk too low the moisture from the mulch or soil will allow bacteria to GIRDLE the plant. It might take a few years for the tree or shrub to die but this is such a common mistake that I keep harping about it!

The bulk of the energy in a branch of any kind is in the apical or terminal bud. When one cuts that off the energy is then transferred to all the axial buds all along the stem. Not great for trees, but usually great for thick shrubs. Make sure that the lower branches, trees or shrubs are longer than the ones above it. Kind of a big salad bowl upside down. That way the leaves on the bottom are getting as much sun in relation to the branches above it.

OK...that is as simple as I feel I can get away with. Grins!

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    Nice review, thanks, but girdling and wrapping it in a damp medium is how we make air layers. In itself girdling is not the kiss of death to the branch above. Girdling is common in fruit growing so that sugars go into making fruit instead of making a bigger tree. Nevertheless, my question is about the effect in releasing buds below - Thimann-skoog said it is because of interruption of the auxin flow, but I keep reading people saying that pruning and girdling have different effects, physiologically. Do they? – Jim Young Apr 17 '16 at 1:02
  • huh! You are talking about cutting a small portion of the vascular system to do layering or promoting certain buds. To girdle is to go all the way around at least that is my understanding. I always am deciding what buds should I promote when I am pruning. I do not have to worry about layering or cutting the food/water flow to promote certain buds. What are you trying to achieve? – stormy Apr 17 '16 at 1:10
  • And I have to add that killing the buds above or on the distal end of the branch is akin to cutting off the apical buds. There is more energy in the apical or even the axillary terminal buds than the ones that are lower. You stop the flow of water and nutrients you kill the buds above and the energy is directed to the buds below. Girdling is stopping the flow of water and nutrients and 'kills' plant material. Cutting above a bud I guess could be called girdling but I've never heard that term being used like that. – stormy Apr 17 '16 at 1:20
  • Pruning on fruit trees I have knowledge about and is critical to keep the tree a height to be able to reach and pick the fruit, get rid of air suckers that use a lot of energy that should be going into the fruit and picking off developing fruits so that you get fewer and tastier fruits versus lame quality. Why would you be layering? Are you trying to add another species to your tree? Espaliers are done this way so that one can have 4 or 5 species of the same fruit on the same tree. What are you layering to produce? – stormy Apr 17 '16 at 1:21
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    Let me try again. There is a bud I want to promote. To promote it, I prune the branch just above it. Does it make any difference if I girdle the branch at the same point instead? – Jim Young Apr 17 '16 at 2:10

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