Grafting Techniques for Wine Grapes

Graft Composition

• Grafting is the combining of two separate plant pieces that results in either a completely new plant or a top-work variety (grafted on established rootstock) with all the desired qualities of a certain grape varietal.

  The two pieces that form the graft are known as the scion and the rootstock. The scion is the piece that will produce the desired fruit, and the rootstock serves as the root system for the vine. During the grafting process, cells form that bind the scion and rootstock together and then eventually form a new water-and-nutrient path called a xylem, and a new sugar pathway called a phloem.

Cleft Grafting

• Considered to be one of the simplest methods of grafting, cleft grafting is usually done in the winter with dormant plants. The rootstock should measure at least 1 inch in diameter and the scion should be of 1/4-inch diameter. The rootstock is split with a blade, and one end of two scion pieces are cut into 'V' shaped points and inserted towards the edges of either side of the split. Care must be taken to match up the cambium on each side. The scions are taped securely into the split and sealed with a special grafting compound.

Chip Bud Grafting

• The chip bud method uses only a single mature bud rather than a scion piece containing multiple buds. Chip budding can be successfully done in late spring through early summer. Vines that have been grafted by the chip bud technique will produce a marketable crop within two to three years. A small angled chip is cut on the side of the rootstock out and replaced with a piece containing a bud cut from a scion; the new piece must be of similar size and line up to the rootstock as closely as possible. To seal it, the graft is wrapped with polyethylene tape.

Bark Graft

• A bark graft is usually done in early spring when the bark is "slipping" enough to pull loose from the rootstock but the sap has not yet started to flow. Bark grafting is used on larger diameter rootstock, and multiple scions can be inserted around the top of a cut-off rootstock. The end of each scion to be inserted is cut at an angle on one side to create a wedge shape about 2 inches long. Two vertical slits are cut into the bark of the rootstock at each place in which a scion is to be inserted. The bark is gently loosened and the scion inserted with the cut edge against the exposed wood under the bark flap. The bark is pulled back into place and each scion is secured by driving a brad in through the bark and scion; all exposed surfaces are coated with grafting compound to seal them.