About the Author
Peter T. MacDonald taught plant propagation and nursery stock production at Scotland’s Rural College. His research focused on propagation techniques and the formulation of growing media. He now delivers workshops on grafting an propagation to colleges in Scotland, the National Trust for Scotland, and horticultural societies. He is a member of the International Plant Propagators’ Society and the chair of the Scottish Branch of the Chartered Institute of Horticulture.
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Introduction
Grafting, the act of uniting part of one plant with another so that they become a single plant, has been used as a method of propagation for several thousand years. The original purpose of grafting was to propagate plants vegetatively, that is, to produce plants that are genetically identical to the parent plant. Over the years, however, other benefits have been developed from joining the roots of one plant and the top growth of another. Grafting is particularly important for pest, disease, and vigour control, but can be used for other reasons.
The development of grafting has involved many people. Some are famous such as Virgil, Alexander the Great, and Charles Darwin. Others such as Philipp Franz von Siebold and Frederick Burbidge are well known in horticulture, although their story may not be familiar. Still others such as Jules Planchon and Charles Riley are little known but deserving of more recognition. In this book, the history and uses are described, showing how nearly all the grafting methods used today had been developed by the end of the nineteenth century. Not until the twentieth century did the science of grafting start to be properly understood—although there is still much to learn. Understanding the scientific principles of grafting has helped to improve and develop the grafting techniques commonly used today. These principles are outlined in this book to provide the underpinning knowledge required to succeed in grafting a plant.
One of the most important requirements for a successful, good-quality grafted plant is the quality of the initial rootstock and scion. The main methods of producing rootstocks are also described—by seed, layering, and cuttings. In practice, however, most people who graft plants purchase their rootstocks from specialist producers. It is important that they are able to obtain plants of the correct specifications, so the requirements for different types of rootstock are provided. The provision of the correct scion material, principally by pruning, is also discussed.
On visiting a number of growers, it was obvious to me that there are many ways of grafting most plants. These may be large differences, such as between budding (attaching a single bud to the rootstock in the field) and grafting (attaching a bud-stick of three or four buds to the rootstock on the bench). Other differences are less obvious, such as waxing or not waxing a side veneer graft.
There is no single, correct way to graft a plant. There are, however, different ways of successfully grafting. These are not necessarily preferred or better—just different. Therefore, it is not possible to provide blue prints for the grafting of different species, there are simply too many options available.
In the chapter on bench grafting, the grafting approaches have been divided into cold and hot callus grafting. The choice of one or the other depends on the time of year and whether artificial heat is applied to the graft. Although growers use many different actual grafts, all of the grafts fall into two types: apical grafts (where the top of the rootstock is cut back prior to grafting) and side grafts (where the top of the rootstock continues to grow above the graft union for a time). This book includes details for managing the rootstocks and grafts after the union.
After the quality of the original plant material and the timing and aftercare of the graft, the third key element to success is the craft skill required to make the graft cuts. How to prepare an apical graft and a side graft is described. If the described techniques are mastered, then it is possible to adapt the use of the knife for any other specific graft required.
Budding in the field is the other main method of grafting used by growers. The two methods of budding described in this book are T and chip. The reasons for using each and the process of successfully carrying out budding are explained.
Most of the book concentrates on woody plants, but the grafting of tomatoes and other vegetable salad crops is becoming increasingly widely used. Although the possibility of grafting these types of plants has been known since ancient times, it has been the Japanese in particular who have led to its popularity in recent years. The advantages of grafted plants are discussed and the methods used for a range of species outlined. Cacti can also be grafted using a technique different from that used for woody and vegetable plants. The grafting of cacti is, therefore, given a separate chapter.
What is the future of grafting? It is always difficult to predict the future, but some of the possible developments and uses are discussed. Finally, at the end of the book are three charts of woody plants, both ornamental and fruit, that may be grafted. If you are looking to graft a particular plant, the charts suggest options for the grafting method to be used and suitable rootstocks.
