Propagation by Means of Budding and Grafting
taken from The Nursery Manual (1934) by Liberty Hyde Bailey
Budding is the operation of applying a single bud, bearing little or no wood, to the surface of the living wood of the stock. The bud is applied directly to the cambium layer of the stock. It is commonly 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 every gradation between budding and grafting proper.
There is no general rule to determine what species of plants should be budded and what ones cion-grafted. In fact, the same species is often multiplied both ways. 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 on young fruit-trees, and with the stone-fruits in nursery practice. It is also used in roses and mat1y ornamental trees. Grafting is in common use for working-over the tops of large trees, and it is also employed extensively in certain kinds of nursery practice as the rootgrafting of apples and the veneer-grafting of ornamental stock.
Budding is commonly performed in the growing season, usually in 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, as soon as the bark loosens; in this case perfectly dormant buds must have been taken in winter and kept in a cellar, ice-house or other cool place.
Budding is always best accomplished when the bark slips or peels easily. It can be undertaken when the bark is tight, but the operation is then tedious and uncertain. It is also more certain when performed in dry clear weather.
But one style of budding is in general use in this country. This is known as shield-budding, from the shape of the piece of bark 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. 130. 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. 131, which is adapted from a print once published by the United States Department of Agriculture. Sometimes the positions are reversed, the bud being inserted from below.
The minor details of shield-budding differ with nearly every operator, and with the kind of plant to be budded. In commercial practice, it is performed in the North mostly 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 earlier in the season than peaches. This is because peach stocks are budded the same season the pits are planted, and the operation must be delayed until the stocks are large enough to be worked.
Most fruit-stocks, particularly 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.
Stocks are sometimes “dressed” or trimmed before set in 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; and such stocks are more expeditiously handled than long and untrimmed ones. A Manetti rose stock, dressed and ready for planting, is shown in Fig. 132. This stock was grown in France, and on being received in this country was trimmed as it is now seen. It will now (in the spring) be set in the nursery row, and it will be budded near the surface of the ground in summer.
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 which might impede the work of the budder, as in the quince, are to be cut off at the same time.
The bud is inserted an inch or two above 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, and to enable it to be set below the surface of the ground when the tree is transplanted, if the planter so desires. It is a common and good practice, also, to place the bud on the north side of the stock to shield it from the sun.
The buds are taken from strong and well-hardened shoots of the season’s growth and of the variety it is desired to propagate. Usually the whole of the present growth is cut, the leaves are removed but a part of the petiole or stalk of each leaf is left (as in Figs. 130 and 133) to serve as a handle to the bud. This trimmed shoot is then called a “stick.” A stick may bear two dozen good buds when the growth has been strong, but only ten or twelve buds are commonly obtained. The upper buds, which are usually not fully grown and are borne on soft wood, are generally discarded.
The buds are cut with a thin-bladed sharp knife. Various styles of budding-knives are in use (Fig. 134), and the budder usually has preference for a particular pattern. The essentials of a good budding-knife are these: the very best steel, a thin blade with a curved or half-circular cutting end, which is light, and handy in shape. The curved end of the blade is used for making the incisions in the stock. The handle of the budding-knife often runs into a thin bone scalpel at the end, and this part is designed for the lifting or loosening of the bark on the stock. The operation of raising the bark by means of this scalpel is often called “boning.” Some budders, however, raise the bark with the blade. A good form of blade, but one seldom made, has a rounded end, the upper side of the curve being ground simply to a thin edge. This blade may be used both for cutting the bark and loosening it, thus overcoming the necessity of reversing the knife every time a bud is set. The blade of a common budding-knife can be ground to this shape. In large fruit-tree nurseries the knife shown in Fig. 135 (and the top one in Fig. 134) is in common use. This is a cheap knife with a stationary blade. When using this knife, the operator loosens the bark with the rounded edge of the blade.
The bud is usually cut about an inch long. Most budders cut from below upwards (as seen in the inverted stick in Fig. 133, and in Fig. 136), but some prefer to make a downward incision. It does not matter just how the bud is cut, if the surfaces are smooth and even, and the bud is not too thick. Some propagators cut the buds as they go, while others prefer to cut a whole stick before setting any, letting each bud hang by a bit of bark at the top, and which is cut off squarely when wanted, as is shown in Fig. 133. On a stick one-fourth or three-eighths inch in diameter the cut, at its deepest joint just under the bud, is about one-fourth the diameter of the twig. A bit of wood, therefore, is removed with the bud, as shown in Fig. 130. There is some discussion as to whether this wood should be left on the bud, but no definite experiments have been made to show that it is injurious to the resulting tree. Some budders remove the wood with the point of the knife or by a deft twist as the bud is taken from the stick. But buds appear to live equally well with wood attached or removed. The bit of wood probably serves a useful purpose in retaining moisture in the bud, but at the same time it interposes a foreign body between the healing surfaces, for the bark of the bud unites directly with the surface of the stock. Probably the very youngest parts of the wood in the bud unite with the stock, but if the budding-knife cuts deep, the denser part of the wood should be removed from the bud. This remark is particularly true, also, of all buds likely to be cut into the pith, as in the nut-trees.
The wound or matrix that is to receive the bud is made by these are light cuts, extending only through the bark. The vertical slit is usually made first and by the rounded end of the blade. This is an inch or inch and a half long. The transverse cut is made across the top of the vertical cut by one rocking motion of the blade. The corners of the bark may be lifted a little by an outward motion of the blade so as to allow the bud to be pushed in, but unless the bark slips very freely it will have to be loosened by the scalpel on the reverse end of the handle, as previously explained.
The bud is now inserted in the cleft of the bark. It is thrust down part way by the fingers, as in Fig. 138, but it is usually driven home by pushing down on the leaf-stalk handle with the back of the knife-blade. The entire bud should pass into the cleft; or if a portion of it projects above, it should be cut off. If the bark peels freely, the bud will slip in easily and will follow the cleft, but if it sticks somewhat, more care is necessary to prevent the bud from running out. If the bark is very tight, it may have to be loosened with the knife throughout the length of the cleft; but budding should be performed, if possible, when such pains is not necessary. The illustration, Fig. 139, shows some of the details of shield-budding (on a small scale) as described by Peck in a Cornell Reading-Course Lesson: 1, bud-sticks; 2, cutting the bud; 3, the buds ready for setting; 4, the stock made ready; 5, the bud inserted.
The bud must now be tied. The whole matrix should be closed and bound securely, as represented in Figs. 140, 143. The string is usually started below the bud, being wrapped twice below and about thrice above it, in fruit-trees, the lower end being held by lapping the second course over it, and the upper end being secured by drawing a bow through under the upper course or sometimes by tying an ordinary hard knot. Waxed string or bandage is sometimes used, as in Fig. 131. Care should be taken not to bind the string directly over the bud itself.
The strings are previously cut the required length — about one foot — and the tying is performed very quickly. Any soft cord may be employed. Yarn and carpet warp are sometimes used. Formerly the most common material was bass-bark. This is the inner bark of the basswood or linden. The bark is stripped in early summer, and the inner portion is macerated or “rotted” in water for four or five weeks. It is then removed, cut into the desired lengths, and stripped into narrow bands — one-fourth to one-half inch wide — when it may be sorted and stored away for future use. If it is stiff and harsh when it comes from the maceration, it should be pounded lightly or rubbed through the hands until it becomes soft and pliable. The best tying material we now have is undoubtedly raffia. It is an imported article, coming from the eastern tropics (the product of the palm Raphia Rujfia), and it is so cheap that it is superseding even bass-bark. It is strong and pliable, and is an excellent material for tying plants in the greenhouse or outdoors. The greatest disadvantage in its use in budding practice is its habit of rolling when it becomes dry, but it may be dipped in water a few minutes before it is taken into the field, or, better still, it may be allowed to lie on the fresh ground the previous night, during which time it will absorb sufficient moisture to become pliable.
In two or three weeks after the bud is set, it will have “stuck” or united to the stock. The bandage must then be removed or cut. It is the common practice to draw a budding-knife over the strings, on the side opposite the bud, completely severing them and allowing them to fall. If the strings are left on too long, they will constrict the stem and often kill the bud, and they also have a tendency to cause the bud to “break” or to begin to grow. The bud on summer- and fall-budded stock should remain perfectly dormant until spring, for if it should grow, it will be injured and perhaps killed by the winter. It should remain green and fresh; if it shrivels and becomes brown, even though it still adheres to the stock it is worthless. A dormant bud, as it appears in the winter following the budding, is shown in Fig. 141. This bud was inserted in August, the picture was made in March, following; the bud should have started to grow in May.
Advantage may be taken, when cutting the strings, to rebud any stocks that have failed. If the bud should begin to grow because of a warm and wet fall or other reasons, there is little remedy except perhaps to head the shoot back if it should become long enough. If the stocks are protected by snow in winter, some of the buds at the base of the new shoot may pass the cold in safety.
The spring following the budding, the stock should be cut off just above the bud, in order to throw the entire force of the plant into the bud. The stock is generally, and preferably cut off twice. The first cutting leaves the stub 4 or 5 inches long above the bud. This cutting is made as soon as the stocks begin to show any signs of activity. Two weeks later, or when the bud has begun to grow (the shoot having reached the length of an inch or two), the stock is again cut off a half inch above the bud (Fig. 142). A greater proportion of buds will usually grow if this double heading-in is done, in outdoor conditions, than if the stock is cut back to the bud at the first operation. Sometimes the stub of the stock is cut long to serve as a stake to which to tie the bud, preventing it from blowing out and keeping it straight. Fig. 143 shows this at 3; and the total removal of the stub is shown at 4. (Peck, Cornell.)
If the root is strong and the soil good, the bud will grow 2 to 6 feet the first year, depending much on the species. All sprouts should be kept rubbed off the stock, and the bud should be trained to a single stem. In weak and crooked growers, the new shoot must be tied, and some propagators in such cases cut off the stock 5 or 6 inches above the bud and let it serve as a stake to which to tie (3, Fig. 143); but this operation is too expensive to be employed on common fruit-trees. The stock, of course, must not be allowed to grow. Late in the season the stock is cut down close to the bud. Peaches and some other fruits are sold after having made one season’s growth from the bud, but pears, apples, and most other trees are not often sold until the second or third year.
“June-budding” is a term applied to the budding of stocks in early summer, while they are yet growing rapidly. It is employed at the South, where the stocks can be grown to sufficient size from seed by the last of June or first of July. Small stocks are usually employed — those ranging from one-fourth to one-third inch being preferred. A few strong leaves should be left on the stock below the bud, and after the bud has “stuck” the whole top should not be cut off at once else the growing plant will receive a too severe check. It is best to bend the top over to check its growth, or to remove the leaves gradually. The bandages should not be left on longer than six to ten days if the stock is growing rapidly. To prevent the constriction of the stem, muslin bands are sometimes used instead of bass or raffia. In hot and dry climates the buds should be set an inch or two higher in June-budding than in the ordinary practice, to escape the great heat of the soil. June-budding is practiced on the peach more than any other tree, although it can be employed for any species that will give large enough stocks from seed by the June following the sowing. In peaches, the bud will produce a shoot 3 to 5 feet high the same season the buds are set, so that marketable budded trees can be had complete in one season from the seed.
A different kind of early summer budding is sometimes performed on apples and other fruit-trees. In this case, the stocks are one or two years old from the transplanting, the same as for common budding, but dormant buds are used. These buds are cut the previous fall or winter in the same way as cions, and when spring approaches they are put on ice – in sawdust, sand or moss – and kept until the stocks are large enough to receive them. The particular advantage of this method is the distributing of the labor of budding over a longer season, thereby avoiding the rush of the regular budding time. It is also a very useful means of top-working trees, for the buds start the same season in which they are set, and a whole season is thereby saved as compared with the common summer or fall budding.
Budders usually carry a number of “sticks” with them when they enter the nursery. These may be taken in the pocket, or some budders carry four or five sticks in the hand. The budder follows a row throughout its length, passing over those trees that are too small to work. It is an old mode to rest on one knee while budding, as in Fig. 144, but some prefer to use a low stool or to sit. It is a common practice, in some nursery regions, for budders to have a low box with half of the top covered to serve as a seat, and the box is used for carrying buds, string, knives and whetstone. The tying is usually done by a boy, who should follow close behind the budder in order that the buds shall not dry out. An expert budder will set from 1000 to 3000 buds a day, in good stock, and with a boy (or two of them for the latter speed) to tie. Peach stocks are more rapidly budded than most others, as the bark is firm and slips easily, and some remarkable records are made by skillful workmen.
Budding is sometimes employed the same as top-grafting for changing over the top of an old tree from one variety to another. The buds cannot be easily inserted in very old and stiff bark, but in all smooth and fresh bark they work readily, even if the limb is three or four years old; but the younger the limb, the greater the proportion of buds that may be expected to live. Sometimes old trees are severely pruned or stubbed the year before the budding is to be undertaken, to obtain young shoots in which to set the buds. The stubbing or heading-back of a citrus tree to get new shoots for budding is indicated in Fig. 145 (adapted from a publication by R. A. Davis of the Department of Agriculture of the Union of South Africa). In fruit-trees six or seven years old or less, budding is fully as advantageous as grafting. New varieties are also budded into old branches to hasten bearing of the bud, for the purpose of testing the variety. Here budding has a distinct advantage over grafting, as it uses fewer buds, for the wood of new sorts is often scarce.
Other kinds of budding
It would not profit us to pause with all the kinds of budding that may have been named. Only those that seem to represent rather distinct classes or departures need be mentioned, and these only briefly.
Prong-budding (sometimes called twig-budding). — A modification of the common shield-bud is the use of a short prong or spur in the place of a simple bud. The bud is cut in essentially the same way as the shield-bud (Fig. 146). This is chiefly used in certain regions for nut-trees, particularly for the walnut, and when the trees are dormant. The method is very much like grafting, for the stock is cut off just above the bud when the operation is performed, and the wound, in addition to being tied, is covered with grafting-wax. In budding the walnut, it is essential that nearly all the wood be removed from the bud, to bring as much as possible of the bark in direct contact with the stock.
Plate-budding is sometimes employed with the olive, and is adapted to other species. A rectangular incision is made through the bark of the stock, and the flap of bark is turned down (Fig. 147). A bud is cut of similar shape, with no wood attached, and is inserted in the rectangular space, and is then covered with the flap, which is brought up and tied. The subsequent treatment of the bud is similar to that of the ordinary shield-bud.
The patch-bud (Fig. 148) is very like the plate-bud, but the bark is cut away from the stock with no hanging strip. This old method has recently been revived for propagating the mango and certain thickbarked subjects. Brown writes as follows on a home-made knife for cutting the patches (B. S. Brown, “Modern Propagation of Tree Fruits,” 1916): “Where very much bark budding is done a special knife for cutting the exact size of the patch is necessary. This can be made by fastening two thin steel knife blades to a block of wood so that two parallel cuts can be made at one time. Such a tool when drawn horizontally across the bark and then vertically, will cut a square patch the desired size. If the blades are set about one inch apart, the patch will be one inch square which will be large enough for most work. The same knife can be used in cutting the buds by drawing it around the twig. After the patch containing the bud is removed the sides can be trimmed to secure a perfect fit.”
H-budding (Fig. 149) is a modification of plate-budding. In this method, a flap is formed both above and below, covering the bud from both ends, and allowing of more perfect fitting of the bark about the bulge of the bud.
Flute-budding. — In this method the bud is not covered by the bark of the stock. Fig. 150 illustrates it. A piece of bark is removed entirely from the stock, and a similar piece is fitted into its place. When the wound extends only part way about the stem, as in the illustration, the operation is sometimes known as veneer-budding. When it extends entirely round the stem it is called ring- or annular-budding. Flute-budding is usually performed late in spring. It is best adapted to plants with very thick and heavy bark. The bud is tied and afterwards treated in essentially the same way as in shield-budding. A species of flutebudding in which a ring of bark is slipped down on the tip of a shoot, which has been girdled for the purpose, is called whistle- or tubular-budding.
Chip-budding (Fig. 151) inserts a chip of bark and wood into a mortise in the stock. It is used in spring, when the stock is dormant and the bark does not slip. The bud is held in place by tying, and it is better for being covered with wax.