Bark Grafting Steps, Tools, Procedure

Bark Grafting

Introduction:

What is Bark grafting? Bark grafting means a plant graft made by slitting the bark of the stock and inserting the scion beneath it and used especially in top working & frame working where two or more scions are inserted at the end of each truncated branch of the stock. Bark grafting is a relatively easy and very successful process done only in the spring after the bark begins to slip and the buds are opening. Bark grafting is done normally from the end of March through mid-April. Some examples of Bark grafting used fruit trees are Persimmon, Mango, Apple, Citrus, Pecan, and Cherry.

Bark grafting tools:

The Tools used for Bark grafting is Bow saw with a raker blade, Shears, Grafting knife, Tack hammer, White glue, Scion wood, Hammer, Grafting compound, White latex paint, Knife, and Wire nails.

Selecting and handling scion wood:

The best quality scion wood generally comes from shoots grown the previous season. Scions must be severed with sharp, clean shears and placed immediately in moistened burlap or plastic bags. It is a good practice during the harvesting of scions & the making of grafts to clean the cutting tools regularly. This may be completed by flaming or immersing them in a sterilizing solution. Isopropyl (rubbing) alcohol works as a sterilant, although it evaporates quite readily. An alternative sterilizing solution can be prepared by mixing one part of household bleach to nine parts water. However, this bleach solution can be extremely corrosive to certain metals.

For best results, harvest as much scion wood as can be used for grafting during the same day. Select healthy scion wood that is free from insect, disease, or winter damage. Be sure the stock plants are of good quality, healthy, & true to type. Scion wood that is frozen at harvest often knits more slowly & in a lower percentage. If large quantities of scion wood should be harvested at one time, follow these steps:

Cut all scions to a uniform length, maintain their basal ends together, and tie them in bundles of a known quantity.
Label them, recording the cultivar, date of harvest, & location of the stock plant.
Wrap the base of the bundles in moistened burlap or sphagnum, place them in waterproof paper bags, and seal the bags.
Store the bundles for small periods, if necessary, either iced down in insulated coolers or in a commercial storage unit at 32° to 34°F.
Never store scions in refrigerated units where fruits are currently kept or have been stored recently. Stored fruits & vegetables release ethylene gas, which can cause woody plant buds to abort, making the scions useless.
Keep the scions from freezing through storage.

Rootstock Preparation:

If the branch on which the scion is to be placed has been previously cut off, it must be cut off another two-inch to have a fresh life & exposed.

Steps for Bark grafting:

The steps used for Bark grafting will be;

There must be a scion every two inches around the circumference of the rootstock. This is essential to form a callus to eventually grow over the exposed rootstock. The lateral rising scion, but one will be removed.
Make two vertical cuts in the bark, the width of the scion apart & just long enough so you can push the scion in without splitting the bark. Raise the strip between the cuts and remove a half-inch.
Include the scion under the bark so only a little of the inside cut surface extends above the stock. The front strip must completely cover the outside diagonal cut.
Make upper nail into Scion. Drive the lower nail through bark & Scion. Be careful not to damage the lower bud or the strip.
A scion must be inserted approximately every two inches of the outside circumference of the stock.
Cover all exposed cuts & top of stock with grafting compound. Be careful not to cover the lowest or outside bud. Cover only the tops of the scions.
Paint scions & stock with the white latex mixture. This is essential to prevent sunburn.

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Factors affecting successful Bark grafting:

Compatibility of scion and stock:

Because grafting involves the joining of vascular tissues between the scion & rootstock, plants lacking a vascular cambium, such as monocots, cannot generally be grafted. As a common rule, the closer two plants are genetical, the more likely the graft union will form. Genetically identical clones & intra-species plants have a high success rate for grafting. Grafting between species of a similar genus is sometimes successful. Grafting has a low success rate when doing with plants in the same family but in different genera. And grafting between dissimilar families is rare.

Cambium alignment and pressure:

The vascular cambium of the scion & stock should be tightly pressed together and oriented in the direction of normal growth. Proper alignment & pressure encourages the tissues to join quickly, allowing nutrients and water to transfer from the stock root to the scion.

Completed during the appropriate stage of the plant:

The grafting is completed at a time when the scion & stock are capable of producing callus and other wound-response tissues. Normally, grafting is performed when the scion is dormant, as premature budding can drain the grafting site of moisture before the grafting union is accurately established. Temperature greatly affects the physiological phase of plants.

Proper care of graft site:

After grafting, it is important to nursing the grafted plant back to health for a stage of time. Various grafting tapes and waxes are used to protect the scion & stock from excessive water loss. Furthermore, depending on the type of graft, twine or string is used to add structural maintain to the grafting site. Sometimes it is needed to prune the site, as the rootstock may produce shoots that inhibit the growth of the scion. These all the above factors are used for successful Bark grafting.

Bark grafting types:

The Bark grafting types will be explained by the following;

Top Bark Grafting:

In this method, the dormant scion must be used. The stock must be grafted when the bark begins to slip. The first step is to cut squarely across the trunk that is 4 to 6 cm in diameter. After the scion is cut across, a sloping cut of about 4 to 6 cm is ready, which is done above the top bud (7 to 8mm). The scion should be joined at the surface against the side of the stock. Finally, fix the scion with two nails & wax it once this is complete. Keep the trunk below the joining point so that it can be free from sprouts & shoots.

Side Bark Grafting:

This method is very similar to the top bark grafting. The square cut is 2 to 3 cm long & 8 to 10 cm wide. The joining branch is then tied. Nails are not used & the branch of the stock above the joining point must be cut off after the scion begins shooting. This process is most commonly used during the growing season.

Slipping Bark Grafting:

The technique has many similarities with the budding methods & can be applied during the same period when the bark peels easily off the stock. The 1st step is to cut back the stock. Next, make a 15 to 20 cm long cut on the bark from the point where the stock was cut back. The cut is similar to the cut used for the T-budding method; however, only cut the barks for slipping Bark grafting. Scion preparation is easy. First, create a sloping cut on the stick. A slight twist with the grafting knife can open the two flaps of bark. After that, the scion must be inserted under the two flaps of bark by pushing it downward. Finally, the incision must be closed with budding tape, which should be wrapped tightly around the stem.

Post Care used in Bark grafting:

The Bark grafting care will be frequently checked to observe if grafting wax is showing signs of cracking. If so, envelop with more wax. In midsummer, select the strongest scion & cut back all others about in half, so most of the energy goes to the strong scion, yet, some leaves are left to make food. Nest year cut back secondary scions to ensure the callus is rising all around. When a callus (bark growth) is well recognized, then all but one scion can be totally removed (maybe 2 years).

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How to make a Bark Grafting?

The Bark grafting procedure is completed in the spring when the bark peels readily. It is chosen by some to cleft grafting because it is done without splitting the wood. It is used in grafting limbs that are larger than is usually a cleft graft. Its weakness lies in the fact that the grafts are not sufficiently supported and, if vigorous growth ensues, are likely to be blown & whipped out by the wind.

Several methods of Bark grafting are used, but all consist of placing the scions under the bark. In one process largely used, the limb is cut off as for cleft grafting. The scion is cut with a long bevel on one side & a very short bevel on the other so as to leave a sharp chisel edge at the lower end.

The scion is then held in place on the outside of the bark & the bark slit down with a knife approximately to correspond with the length & width of the bevel surface of the scion. The lower end of the scion with the long bevel towards the stock is then pressed under the bark between the two cuts, the bark peeling as the scion is pushed downward. The lifted bark is then cut away even with the top of the short bevel & the scion tacked tight to the stock with two small nails or brads. Other scions at intervals of 2 to 4 inches are put in place in a similar manner entirely around the stub. The entire scions & cut surfaces of the stock are covered with melted wax.

In shaping the scion, some prefer to cut halfway during the scion at the top of the long bevel forming a shoulder that is placed against the top of the stock, giving added support to the scion. Another process is to cut the scion to a very long, slim bevel from one side, slip it down between the bark, and tack it in place. If the bark is heavy, it is essential to cut the bark in front of the scion before it will loosen enough to allow the scion to be pushed down into place. The scion is then secured & waxed in the usual way.

In placing scions in Bark grafting, care must be taken that they are cut with a smooth outside as nearly as possible to fit the surface of the stock. A small block plane has been found very valuable in smoothing up & cutting the long bevel in this type of grafting. The knife on the plane may even be ground to a somewhat rounded cutting edge instead of straight. This will enable the beveled surface of the scion to be cut a little concave to fit the surface of the stock more closely. The small nails or brads used in bark grafting must be very slender so as not to split the scion & should have wide heads so as to draw the scion closer to the wood. Those normally known as cigar box nails or small nails used in making up bee supplies are fine for this purpose.

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