Graftage may be divided into three general divisions, between which, however, there are no decisive lines of separation: 1. Bud-grafting or budding, in which a single bud is inserted upon the surface of the wood of the stock. 2. Cion-grafting or grafting proper, in which a detached twig bearing one or more buds is inserted into or upon the stock. 3. Inarching or grafting by approach, in which the cion remains attached to the parent plant until union takes place. Each of these divisions can be almost endlessly varied and sub-divided, but in this discussion only the leading practices can be detailed. The following enumeration, after Baltet, will give a fair idea of the kinds of grafting which have been employed under distinct names:
Particular Methods.—Budding. Budding is the operation of inserting a single bud, bearing little or no wood, upon the surface of the stock. The bud is nearly always inserted under the bark of the stock, but in flute-budding a piece of bark is entirely removed and the bud is used to cover the wound. There is no general rule to determine what species of plants should be budded and which ones cion grafted. In fact, the same species is often multiplied by both operations. Plants with thin bark and an abundance of sap are likely to do best when grafted; or if they are budded, the buds should be inserted at a season when the sap is least abundant to prevent the “strangulation” or “throwing out” of the bud. In such species the bark is not strong enough to hold the bud firmly until it unites; and solid union does not take place until the flow of sap lessens. Budding is largely employed upon nearly all young fruit-trees, and almost universally so upon the stone-fruits. It is also used in roses, and many ornamental trees. Budding is commonly performed during the growing season, usually in late summer or early fall, because mature buds can be procured at that time and young stocks are then large enough to be worked readily. But budding can be done in early spring, just as soon as the bark loosens; in this case perfectly dormant buds must have been taken in winter. Budding is always best performed when the bark slips or peels easily. It can be done when the bark is tight, but the operation is then tedious and uncertain.
Shield-budding.—There is but one style of budding in general use in this country. This is known as shield-budding, from the shield-like shape of the portion of bark which is removed with the bud. Technically, the entire severed portion, comprising both bark and bud, is called a “bud.” A shield bud is shown natural size in [Fig. 61]. This is cut from a young twig of the present season’s growth. It is inserted underneath the bark of a young stock or branch, and is then securely tied, as shown in [Fig. 65].
Fig. 61. Shield-bud.
The minor details of shield-budding differ with nearly every operator. In commercial practice, it is performed in the north from early July until the middle of September. In the southern states it usually begins in June. As a rule, apples and pears are budded before peaches. This is due to the fact that peach-stocks are nearly always budded the same season the pits are planted, and the operation must be delayed until the stocks are large enough to be worked. Most other fruit-stocks, especially apples and pears, are not budded until two years after the seeds are sown. The plants grow for the first season in a seed-bed. The next spring they are transplanted into nursery rows, and budded when they become large enough, which is usually the same year they are transplanted. The nurseryman reckons the age of his stock from the time of transplanting, and the age of the marketable tree from the time when the buds or grafts begin to grow. The young stocks are “dressed” or trimmed before being set into the nursery. This operation consists in cutting off a fourth or third of the top and the tap root. This causes the roots to spread and induces a vigorous growth of top because it reduces the numbers of shoots; and such stocks are more expeditiously handled than long and untrimmed ones.
Stocks should be at least three-eighths inch in diameter to be budded with ease. Just before the buds are set, the leaves are removed from the base of the stock so that they will not interfere with the operation. They are usually rubbed off with the hand for a space of five or six inches above the ground. They should not be removed more than two or three days in advance of budding, else the growth of the parts will be checked and the bark will set; any branches, too, as in the quince, which might impede the work of the budder, are to be cut off at the same time. The bud is inserted an inch or two above the surface of the ground or as low down as the budder can work. The advantage of setting the bud low is to bring the resulting crook or union where it will not be seen. It is a common and good practice, also, to place the bud upon the north side of the stock to shield it from the sun.