Building a Tree, The Grafting SkillHome Orchard Society Publication
The goal of grafting and budding is to join together two living plant parts so that the whole grows as one plant. One of the two pieces supplies the roots and perhaps a length of trunk; this piece is called the rootstock. The other piece, the scion, provides the rest of the trunk, plus the stems, leaves, flowers, and fruit. Each part retains its own identity.
Grafts are usually made because a variety of plant does not grow true to seed and is extremely difficult either to layer or root from cuttings. In order to maintain a high-quality line of fruit trees, then, cuttings must be made from a successful tree and grafted on established roots.
Success in forming a permanent graft union between plants or plant parts depends upon compatability and cambial contact. The closer the botanical relationship between rootstock and scion, the greater the chance of a successful take. It is also critical that the cambium (the thin layer of cells between the outer sapwood and the inner bark) layers of both the rootstock and scion be in close proximity and that they be held there until healing is complete. The rate of callusing also varies with air temperature and plant species.
Simply stated the reasons for grafting and budding are:
- To perpetuate a variety.
- To increase the ease and speed of multiplication.
- To produce some radical change in the size, nature, habit, adaptation, or disease resistance of rootstock or scion.
Gathering Scion Wood
Winter is the time to gather scions for spring grafting. Consider these suggestions for getting the best wood.
1. Timing. The best time of year to gather scionwood will vary with bio-regional climate and type of fruit. The wood should be in the dormant stage and inspected for freeze damage.
2. Authenticity. The best wood will be taken from healthy trees that have proven themselves as productive and true to name and type. Label each variety carefully at cutting time. Use a water proof label and marker.
3. Selection. For most types of dormant grafting, one-year old wood (last season's growth) is generally considered best. Wood about a pencil diameter and 6 to 10 inches long is usually ideal.
4. Storage. The essential requirements are to keep the wood moist and viable, but not so wet as to rot, and maintaining a cool enough temperature to prevent premature bud-swelling and protecting against freeze damage. Store scions in tightly sealed plastic bags with some moisture in refrigeration until ready to use.
5. Disease. Be careful not to select scion wood from trees suspected of harboring infestation of bacterial, viral, or fungal disease.
The season for budding is in the late summer. This is desirable because buds of the present season are mature and the bark of the stock can still be slipped.
Most fruit tree propagators rely on a few simple types of grafts. The following five methods can facilitate the grafting or budding of almost any type of fruit or nut tree over a wide range of conditions.
1. Whip-and-Tongue Grafting.
This is the most popular method for dormant grafting where stock and scion are of similar diameter. This is suited to bench grafting indoors and starting rootstock & new scions.
2. Cleft Grafting.
Most often used for dormant grafting where the stock is larger than the scion. This is a good method for topworking older trees to new varieties.
3. Bark Grafting.
Used, like cleft grafting, where the stock is larger than the scion; must be done later in the season when the bark is slipping freely. This is frequently used with walnut and persimmon.
4. Shield Budding.
This method requires only a single bud for each bud-graft. It can be done only at times of intense cambium activity when the bark will slip. This is the main form for commercial propagators during the summer months.
5. Chip Budding.
This uses only a single bud–but can be performed over a long period regardless of bark slippage. This is excellent for warm weather grafting of difficult species like nuts.
Probably the most common reason for graft failure is allowing air to dry out the graft. To prevent this, all cracks, wounds, and the cut end of the grafting stick should receive a liberal coating of a sealing compound.
Be sure you permanently label your new tree. Even keep a written record.
The amateur may think grafting is the province only of the professional grower but it is easy and wonderful to watch. For further instruction attend a workshop or read from a book like The Grafter's Handbook by R.J Garner.