I also suspect that shorter scions are best but here are some longer scions just because I wanted to give it a try. There are plenty of issues with longer scions.
Approx 15"
Approx 18"
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nobody really knows how sap rises.
i somewhat find capillary/wicking action a plausible factor, but will have to disagree re: atmospheric pressure. The only entities that atmospheric pressure āpushes upā are entities less dense than the main ingredients of air.
Pure hydrogen and helium being the two that i know of which get displaced upwards.
Everything else will sink, and the pressure of the atmosphere will bear down on it.
Much like oil will get displaced upwards by water, but the oil on top of the water will still exert pressure on the water it is sitting on. Additionally, the atmosphere(albeit lighter than oil or water) will still exert pressure on this container filled with water and oil.
now-- water-- especially with solutes(like sap), is very dense. We could surmise capillary action, cohension-tension, and osmotic gradients play major roles in the upward movement of sap, but it is still a mystery of science. Still, none of these are immune to the universal effects of resistance and gravity. If one has a capillary tube, which one could dip into standing water, then yes, some water will rise, but only to some extent, so length clearly has a limiting effect, and resistance and gravity play huge roles in preventing the upward movement.
lastly, the main reason why we must strip a stemsā leaves-- when we try to strike stem cuttings directly into soil(say a rose stem or sugar cane), is because the cuttingās surface area and living parts get disproportionately enormous compared to the source of moisture, since it has lost all of its feeder roots and will have to get by on water being absorbed inefficiently through its rootless underground stem. The success rate is very low if not nil, if one will stick a rose stem onto earth without stripping it of leaves and if it is many inches long sticking out of the ground.
striking cuttings with just a bud or two above ground, with a relatively longer stem underground will maximize transpiration losses, and maximize moisture absorption which would more likely sustain the few buds that the cutting is required to nurse.
when we graft, we wonāt have the luxury of an underground stem, and are held hostage by what few xylem and phloem āpipesā we managed to approximate, so if the scion is long with too many buds to support/keep turgid, one could expect similar success rates as in the cuttingsā analogy.
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yet another very good and thoughtful post. Transpiration issuesā¦yep.
http://www.science4all.org/le-nguyen-hoang/the-amazing-physics-of-water-in-trees/ This is an interesting video on how water gets to the top of trees.
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You can find this in Wikipedia:
In plants and trees[edit]
The capillary action is enhanced in trees by branching, evaporation at the leaves creating depressurization, and probably by osmotic pressure added at the roots and possibly at other locations inside the plant, especially when gathering humidity with air roots.[23][24]
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thanks for the links Johnnysapples.
circulation of sap is evidently more sophisticated, enigmatic, and mysterious, compared to circulation of blood in animals.
i meant to write āoffset transpiration lossesā, instead of āmaximize transpiration lossesā
wow! your grafts are quite intense, from a mehanical point of view. That it actually ātookā and even budding along its entire length means you grafted it quite perfectly, as if it was never compromised.
Thanks @Appleseed70 !
i could still be wrong, of course, the mere āstudentā that i am.
It really is a fascinating phenomenon but quite elusive one. Funny that weāve split the atom, fused the atom, , been to the moon and back, yet we still have no cure for cancer, and no idea how sap could be āpumpedā 300 feet high into the canopy of giant eucalypts
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I thought I had an understanding how water got to the top from researching it before. I guess there is more to it than I had in my mind.
Auburn your grafts do look impressive! Did the end one break first?
I agree with others Billā¦your cuts must be perfect. It really does appear as though it is growing completely normal and as though it was never cut or joined. Good job brother.
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Very interesting!
When I prune figs or grapes in the late winter, there are no leaves. No transpiration. But they pull up lots of sap and leak it out. To the point where its dripping. I slso have a grafted apple scion thatās doing that now.
So must be osmotic. There is no evaporation driving that in leafless pruned plants.
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I most likely should not dive into a subject of which bud should pop first with my limited knowledge. The one thing I can offer is careful observation of what I do. The two long scions posted were almost level which might lend itself to the even gravitational pull on the resources that cause the timing of bud opening. Some of the other long scions I grafted were pointed upward and one pointed slightly downward. The ones pointed upward tend to pop buds on the end first, The one pointed downward appeared to leaf out evenly. One of my interest in the long scions was to replace short runted lower limbs on dwarf apple trees and see if they would fruit the following year. I will remove the tape soon and add a simple split for a little while. Bill
In the grafters handbook by rj garner, he refers to the necessity to use long scion with many buds each when frame working a large tree as opposed to top working to lesson the vegetative vigor and bring fruiting wood back online sooner. I believe his distinction being a frame worked tree has retained the original trees framework, whereas a top worked tree has been cut back much more severely.
Hereās a google books link to the page
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Very interesting, thanks for posting. In my case Iām looking for quick fruiting whether top working or āframeā working. Am just about finished this grafting season so canāt put this to work until next year. I have this book somewhere. Itās probably the same place as the scions I canāt find. I need a scion inventory system!
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Would like to here what everyones grafting projects are this year. Any interstem grafters? Anyone trting longer vs. Shorter grafts? We have enough special projects that i cant commit to more but im very interested in some of the concepts discussed.
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Iām going to graft a little bit of everything this year. Including my first peach and apricot. Last year I had great success with apples and pears. But from what Iāve heard peaches, nectarines, and cots are a whole different beast. With cherry and plum being somewhere in the middle. Iāll graft my apples and pears earlier and wait until it warmer and buds are popping to try peach.
I also want to try side grafting a cherry tree of mine thatās misproportioned. Have not attempted a side graft yet.
Last thing graft related is dealing with thin scions. I have a lot of small thin wood this year and I think Iāll be cleft grafting a lot of it.
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The real trick to stone fruits is pleasant consistent weather and growth on the rootstock. Once the rootstock starts pushing growth its time to graft. Plums are very easy to graft similar to pears and apples and cherries are graftable as well. Sour cherries were easier for me I should say and the sweet cherries not so much. Apricots are hard because our weather fluctuates so much. If it warmed up and stayed that way it would be no problem but we have spells of hot and cold and for peaches and apricots that makes for tough grafting. Keep us updated and let us know how you do if you would. I know some people wrap their grafts and others put a little plastic tent on theirs. I just wrap the union and use wax or grafting seal on the end of the scion. I should be ashamed blaming the weather because people do it inspite of bad weather.
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I should be finished after top working a wild apple to spy this year. I am going to cut some long branches just a couple off a wild apple that I converted to Honeycrisp. Those branches are encroaching on my rainier cherry. I want in time to get the fruit closer to the trunk. I want to graft my peach tree too. Iām still working on that skill with the weather swings here in Mi. I bought five plum rootstocks and five cherry. I will plant some and graft some. I have to read a bit more on those, but Iāll plant them and grow them to graft onto. A couple I will try making trees with right away. Every year I try more and more and work on techniques used for different circumstances. Grafting with long scionwood can give you spurs to grow fruit on the next year but is that the smart thing to do? Grafting short ones is better for success. It has less chance of coming apart. A couple years goes by in no time and then it doesnāt matter that much anyway. Thatās my thoughts.
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