Thread Grafting

tmjudd1

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Should a thread graft fit 'tightly' into the hole drilled to receive it?
Also... would it be of any benefit to scrape the outer layer of bark off of the thread, in the area that the thread will be seated into the trunk?
 

0soyoung

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The hole should be just big enough to pass the buds. Then one uses toothpicks, wood skewers, or the like, to fit the thread snugly against the top of the hole. Then you cover the two sides so that the cambiums on the entrance and exit sides don't desiccate (it isn't the end if this happens, just that your graft will take much longer to establish).

Scraping the bark on the thread is not a good idea as the normal damage response on a stem that thin is enough to clog the entirety of the xylem = the exit end of the thread (your graft) quickly dies of desiccation. As the thread grows, the hole you drilled acts as a tourniquet on the thread - the two cambiums find each other, make a common xylem. You will ultimately see the thickness of the thread on the insertion side is much thinner than the exit/graft side..
 

Shibui

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There is no way you can thread a shoot through and get it to fit tightly. The buds at the nodes always sit proud of the stem so threading a shoot through a small hole will just strip all the buds off.
Hole should be just large enough to pass the buds through without damage and the thread is wedged to hold it against one side as Osoyoung has already mentioned.
I disagree about scraping though. I normally scrape a small amount of bark from the thread, just where it will be wedged against the 'out' side of the hole - aiming for callus to help unite the graft quicker than constriction. Maybe it depends on the diameter of the threaded shoot?
Regardless of removing bark, I agree that sealing the wounds will help it to heal and then unite.
 

RVMcC

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Question... why wedge the shoot to the side? Why not wedge the shoot from to top downwards? Doesn't the trunk move sap/energy upwards more than sideways? I just did a thread graft on my Trident stump and thought a wedge (toothpick) at the top pushing down would be better? Comments?
 

sorce

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Why not use a cutting from the same tree as the "jammer", it increases your odds of a graft taking by 20%or so!


I think up is traditional. But there is another level of detail that makes it a case by case basis, so no tradition!

....

Reckon just because the out is thicker than the in doesn't necessarily mean it took.

I scraped between the crease of one 2 days ago, like one would rewound a hole to heal it.

I scrape after the fact.

Sorce
 

0soyoung

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Question... why wedge the shoot to the side? Why not wedge the shoot from to top downwards? Doesn't the trunk move sap/energy upwards more than sideways? I just did a thread graft on my Trident stump and thought a wedge (toothpick) at the top pushing down would be better? Comments?
Good thinking about these things, but sap/energy is made by the foliage and comes down the tree in the phloem (inner bark, just atop the cambium which are those cells that divide and make the stems and tree in general thicken). In effect, it is a lot like pouring thick syrup down the tree.

A hole with a stem through it is a lot like a pole in a river - there is kind of pile of water upstream (top of the eye) and a lack downstream (below). So, the growth happens much faster above than below the hole --> wedge the thread tightly toward the top of the hole.

Now, if you get this, you also have an 'aha moment' about the sense in Ebihara's big branch pruning technique! 🤓 :cool:
 

River's Edge

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Why not use a cutting from the same tree as the "jammer", it increases your odds of a graft taking by 20%or so!
For some species it is easier to get the Thread extension with cuttings grown for the purpose. Here is one example where that is the case! Azaela with very thin branches, difficult for approach graft and long time to get extensions to circle around and enter from the right angles!
Solution take cuttings, grow quickly and prune to promote extension without side branches to interfere with thread grafting! Satsuki Azalea requiring two lower branches after trunk reduction. IMG_1081.jpegIMG_1082.jpegIMG_1083.jpeg
 

River's Edge

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Reckon just because the out is thicker than the in doesn't necessarily mean it took.
Agreed, Often just a sign that the growth is occurring and restriction is present! Using the wrong sealant on the original graft will often cause the thread graft to fail, causing just enough impediment to stop the union. I avoid liquid sealants in favour of putty or paste.
 
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