To create a "true" genetically identical version of fruit tree, with all its desirable characteristics, a graft is required. This involves using a live stem from the desired tree, called a scion, and implanting it into a similar variety of the tree that acts as a root stock. The root stock will then nourish the stem as it grows. The two will eventually merge to form one plant. Grafting a fruit tree requires some special care, preparation and treatment. There are a variety of grafting techniques to choose from, each with its advantages and level of difficulty.
Things to Know About Grafting
Scions are collected in late winter, when fruit trees are still dormant. They are cut and stored in refrigeration until needed. Grafting is done in the spring when buds are beginning to open on trees that will act as root stock. Root stock should be from a hardy, disease-resistant variety of the fruit tree.
The most important point to remember about grafts is that the inner layers of bark in the root stock and scion must align for the graft to take.
The Whip Graft
Whip grafts are used when branches are relatively small. A branch from the root stock tree is cut off at an angle. The branch is then split slightly. The cut end of the scion is prepared in a similar manner. The angles are then turned face to face and the split ends wedged into each other. The graft is then wrapped, coated with grafting compound and left until the scion shows signs of growth.
The Cleft Graft
This graft is commonly used for working the tops of established trees. The graft is made between 2 to 3 feet of the center of the tree on either the main trunk or major branches of the tree. A branch between 1 and 2 inches is cut off squarely with a hand saw, then split slightly. Two scions are prepared by trimming the cut ends to form a wedge. Each scion is inserted into either side of the split so the inner bark on the scion aligns with that of the branch. The graft is wrapped and sealed. Once the scions begin to grow, the less vigorous of the two is removed. The modified cleft graft is similar to the cleft graft, only the root stock is smaller and only one scion is used.
The Side Graft
In this graft, a deep, downward cut in a smooth part of a branch is made. A scion is prepared as for a cleft graft. The branch is bent to open the cut and the scion is inserted, ensuring that the inner layers of bark align. The branch is then cut off. Usually, binding is not required and the graft can be coated with grafting compound.
The bridge graft is used when a tree's bark has been girdled, threatening the life of the tree. In this technique, the bark is trimmed to above and below the girdling. Then, larger scions with wedge ends are inserted under the bark of the tree. As the graft takes, it will act as a bandage, to provide a pathway for water and nutrients until the tree can heal.
A form of grafting known as budding is used to insert a single bud under the bark of a branch. A bud is first removed to form the scion by slicing under it along the stem to remove an oval piece of bark with the bud. This is trimmed and inserted with the bud facing out in a raised "T" shaped incision in the root stock. The bud is held in place with tape.