This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
70. In gentlemen's gardens, where the walls are higher than ours, four lower and four upper secondary branches may be established on each of the main branches; but as they are formed in the same way as the other three, I shall confine myself to describing the operation according to the method I pursue with my own wall-trees.
71. The operation that forms the lower secondary branches, which should always be permitted to grow before the upper ones, is based upon the above-mentioned principle (64); that pruning to a wood-bud favors its development, and that of the eyes that are beneath it, in proportion to their proximity. Therefore, the wood-bud, which is immediately below the terminal one, is that which takes the next greatest growth. This being the case, when we want to form a lower secondary branch, we prune the leading shoot of the main branch (a, fig. 7) to an eye on the upper side or in front of the shoot, the next lower bud being on the under side. The first is intended to prolong the main branch, the second to form a lower secondary.
72. For the formation of a lower secondary branch, we can also make use of a shoot or of a summer lateral, if they spring from immediately below the bud to which the main branch has been pruned. The shoot or summer lateral is either left entire, or pruned back to the first wood-bud; and it is trained in the direction which it ought to take. It is sometimes useful to facilitate its development by one or more longitudinal incisions on the main branch immediately above it, and extending to the base of the shoot.
73. In pruning the lower secondary branches, it is best to cut to an eye situated on the under side of the branch. In cutting to an eye on the under side, the shoot from it has a natural tendency to take the direction we desire. The same holds good in pruning the main branches, after the formation of the three lower secondary branches; but previously it would not, owing to the alternate position of the buds. For the prolongation of the main branches, we should generally cut to an eye so situated as that the one immediately below it may be on the under side for the development of a lower secondary branch. The eye to which a main branch ought to be shortened must not, however, be chosen in all cases in this manner. Under some circumstances it may be preferably shortened to a bud placed on any side, provided it be at the proper height, and the position of the shoot is afterwards regulated by nailing. When a branch is stronger than its fellow, its pruning must be so managed as to check it; while the weakly branch must be pruned in such a manner as to promote its growth: and thus equality will be ultimately restored.
With this aim, I cut back the stronger to a triple wood-bud (13), and destroy the middle one, which is always the strongest, with the point of the pruning-knife. As soon as the remaining two are grown up, I preserve the one that appears the best fitted for the object in view, and the other is cut off. Lastly, when there is a strongly-marked inequality, the weaker branch may be cut back to a vigorous shoot which may be made the leader; and in training, this must be allowed to grow as freely as is consistent with the regularity of the tree.
74. With regard to the upper secondary branches, they are formed, when it is time to do so, from a fruit-branch suitably placed, of the thickness of a quill throughout its length, of moderate vigor, and which has been several times pruned back. To accomplish this, the successional bearing-shoot is cut out close to its base, and the branch that has borne fruit the year before is pruned to a wood-eye for a leading shoot. The formation of upper secondary branches must be watched progressively, in order that their base may be always well furnished with branches that shall not be over-vigorous for fruiting. This requires much care, and pinching and disbudding must be resorted to, in order to check the tendency of the sap to rise most abundantly through vertical channels. They are also pruned to a triple bud for a leader; and frequently, when they still prove too vigorous, they are cut back to a well-placed lateral, the latter being shortened to a suitable wood-bud.
75. From what has been said, it is now evident that there is no great difficulty in pruning wood-branches; and any one can insure success when the operations necessary to be performed on them, from the time the tree is planted till that of its complete formation, shall have been detailed.
76. 2d, Pruning the Fruit-branches. In a Peach tree, trained according to the square mode, if we except the two main branches and the twelve secondary branches that compose the skeleton, all the others may be considered as shoots and fruit-branches of a mixed nature; for the greater number of them bear both leaves and fruit.
77. The way of obtaining the greatest possible quantity of fruit from a tree, without exhausting it, consists, then, in the art of keeping the whole extent of all the leading branches well furnished with shoots capable of producing fruit, a property which they lose when more than one year old. We must therefore know how to procure a succession of these by suppressing those branches that have borne fruit, and which, after that, are merely wood-branches. This is done by properly pruning the fruit-shoots, and by promoting the growth of others to succeed those that have borne fruit.
78. On the fruit-branches there are eyes which may be single, double, triple, quadruple, or even more numerous ( 9 - 14 ). Hence there are four sorts of fruit-branches. The first, which has single eyes, usually a flower-bud, is long and slender, and is terminated by a pushing-eye or growing-point It is shown in fig. 1. The terminal pushing-bud is seen at a; all the buds, 6, are single and flower-buds. Sometimes it has also at its base another wood-bud, a; and when this is the case, the shoot is considered well constituted. These wood buds are found more especially on the under side, and at the base of wood-branches, particularly in aspects not much exposed to the sun.