The methods for bark grafting are all similar. The scion is placed between the bark and the wood on one side of the stock. The key to successful bark grafting, is making sure that the cambium on the scion is placed in direct contact with the stock’s cambium.
To begin with the modified rind graft, you must cut off at least 1/2 of the stock, leaving a stump that is less than 4 inches in diameter.For a faster healing process, I recommend trees in the 1.5 to 2.5 inch diameter range.
Next, you must inspect the stump and look for the “flat” side of the stem. On this side, you need to make a downward incision with your knife, cutting through the bark, around 3 inches long.
Then you need to carve the scion into a shape that will fit underneath the bark and maximize the cambial contact. Begin by making a deep cut, removing about 2/3rds of the thickness of the scion.This cut is approximately 2.5 inches long, and has a pronounced shoulder at the top of the cut.
Turn the scion over and make a shallow cut into the wood of the back side of the deep cut. This cut isn’t made parallel to the deep cut, but is angled to the one side. When done, I have a thin piece of bark that is adjacent to the deep cut on one side with a much thicker strip on the other side. The cut on the back side of the scion must begin just below the shoulder of the deep cut, and must give the scion a wedge shape when finished.
Next a third cut needs to be made, perpendicular to the deep cut, along the thick bark strip edge. Make this cut deep enough to expose the cambium and make sure to leave a strip of bark between the backside cut and the perpendicular cut. At this point the scion should have a triangular shape in cross section. Complete scion preparation, by making a chisel point on the end of the bud stick. This final cut must be made on back side of the scion.
Then you need to insert the scion into the stock. Use a grafting knife to gently pull the stock’s bark away from the wood, on the left side of the bark slit. Inserting the scion between the bark and the wood of the stock, you need to tap the scion down into the stock until the shoulder of the deep cut fits snugly against the upper side of the stock. The deep cut must be facing the wood, and the shallow cut must be covered by the raised bark flap. The perpendicular cut must d fit snugly against the bark slit.
Secure the graft union with staples (use a 5/16 staple from a light duty staple gun). It is vital to staple the bark down firmly against the scion. Make sure all the air pockets have been removed.
Cover the graft union with aluminum foil and a plastic bag. Finally, attach a dowel to the stock with black electrical tape, to prevent the birds from breaking the scion out.
A good time to look over the previous year’s bark grafts would be early spring. In the photo, you can see that 2 grafts were applied to this tree the previous year, but only one of the 2 grew. We left the aluminum foil and plastic bag (applied at the time of grafting) on the tree to protect the graft union during summer. A strong wooden stake attached to the tree is also visible. This was used to support the graft and to prevent wind breakage.
Begin by removing all the wrappings. When the foil was removed, the failed scion just fell off the tree (there was no callous formation to hold it in place). You can see how callous tissue formed at the top of the stock where the scion was inserted under the bark.
The second step in maintaining this graft would be to trim the top of the stock. You will see a distinctive swelling in the bark of the stock that runs at a diagonal angle from the scion to the opposite side of the tree, approximately 1.5 inches down the trunk. To encourage the healing process, you will need to cut the corner off the stock just above that swelling.
In order to find the exact location to trim the stock, you need to use a knife to peel back some of the bark on the side of the tree opposite to the graft. You will see that the tree has created a barrier to wall off the wound you made when grafting. Above the barrier the bark will be dark and possibly decaying. Below the barrier, the bark is alive and tan in color. In the photo you will see we’re using a hand saw to cut away the dead wood above the barrier. See the tan, living bark below the cut. Also see that we cut just above the diagonal swelling in the bark.
By trimming the stock at the exact spot that the tree is trying to seal the wound off, you will be enhancing the healing process and reduce the time needed to keep the graft supported with a wooden stake.
The step step in early spring maintenance is to prune the tree. Prune a few of the lower limbs in order to force more of the tree’s energy into the scion (note the fresh pruning wound below the graft union). Next, prune the scion so that you will have a nice central leader tree
The key to a arrowhead grafting successfully is in carving the scion into the correct shape. First you need to whittle the scion down into a thin strap. This strap must be thinner and narrower towards the bottom of the scion. There should also be a pronounced shoulder at the top of the cut surface.
Next turn the scion over and very carefully shave off some of the bark on each side of the scion. Make sure that the cut is deep enough to expose a thin strip of white wood along each edge. By exposing the wood, you are ensuring that cambial tissue is revealed. A thin strip of bark must stay down the middle of the scion. This graft gets it name from the two cuts that you make on the back side of the scion. I looks as though you are sharpening the edges of an arrowhead.
Next you need to insert the scion into the stock. At least 2/3 of the top of the stock tree needs to be cut.Make one vertical incision approximately 3 inches long, right through the bark of the stock. Insert the scion under the bark right down the center of the incision. You should see the strip of bark that you left on the back of the scion exposed through the crack in the stock’s bark. Please note that at this particular point, the bark of the stock is cupped away from the cut surfaces (and, more importantly, the cambium) of the scion.
Use a light duty staple gun with 5/16 inch staples, to form the stock’s bark closely over the scion. Starting at the bottom, use the staple gun to press the bark up against the edge of the scion and secure with a staple. 6 staples are recommended, 3 per side.Insert them vertically to hold the bark firmly against the scion.The success of this grafting method depends on how successfully you are able to force the stock’s bark to conform to the scion.
To secure the scion even further, wrap the graft union with grafting tape (1/2 inch wide, 4 mm thick, plastic plant tie ribbon). The tape will help hold the stock’s bark firmly against the scion.
Complete the grafting process by using the same wraps used for all pecan grafting methods. Cover the graft union with aluminum foil to prevent sun burn.Put a plastic sandwich bag over the scion and the stock in order to maintain high humidity (you will need to snip one corner off the bag). Then use grafting tape to seal the plastic bag around the scion tightly, and then again around the stock just below the graft union.
And finally, attach a dowel to the stock using plastic electrical tape (black tape). This dowel extends about 2 feet above the scion and makes a perch for birds to land on, instead of on top of the scion. Numerous new grafts have been damaged by perching birds when scions aren’t protected properly.
Once growth starts on the scion, tie the new growth to the dowel with grafting tape in order to stop the wind from breaking out your scion.
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