PRUNING, the removal of parts of plants in order to economize and divert energy in desired directions. Fundamentally the various objects for which plants are pruned are (1) training, in which the limbs are started and dis posedas desired; (2) pruning proper; (3) trimming or the shaping to some artificial form. The first is of prime importance in the early years of orchard fruits, but is of smaller and smaller application as the subjects dealt with are shorter-lived or less tree-like. The second is important, as a rule, during the whole life of the plant, in many cases, especially of trees, commencing when the plants are set. The third is usually of small importance, at least in Amer ica, being employed mainly with such orna mental subjects as hedges, topiary specimens and dwarf trees.
Popular opinion concerning the practice has changed within recent years. Formerly it was against pruning upon the ground that the plants suffered and that the practice was unnatural. But nature is an inexorable pruner, as the straight limbless trunks of forest trees and the dead twigs and branches of trees left to themselves sufficiently show. The horticulturist improves upon nature in doing his work intelli gently, not only with respect to what shall be removed, and when, but how it can be best done, so as to enhance the healing of the wound. The practice is essential to successful orchard fruit culture and to a greater or less extent with other plants. With woody plants that have been grown in nurseries it is necessary to cut back the tops to approximate a balance between the top and roots which latter have been necessarily reduced in digging. The usual practice in this matter is to remove at least one-half of each branch that is to remain and to cut off all the others. Many orchardists trim off all the limbs and some leave nothing but a switch or even a stub, claiming that they can then form the head of the tree where they desire and that the tree more quickly recuperates than if a larger proportion of top is left. Certain it is that in practice the trees untrimmed at trans planting time generally suffer severely.
Among the principal objects sought in the pruning of fruit-trees the following may be mentioned: To divert plant-food from wood production into fruit formation and develop ment of improved specimens; to keep, not to force, the tree in bearing condition, which is secured by regular annual attention and not by intermittent neglect and butchery; to prevent the excessive production of wood which is usu ally at the expense of fruit production and or dinarily is a sequence of excessive pruning; to keep the tree within manageable limits so as to facilitate cultivation, spraying and harvest ing; and to admit light and air to the tops so that the fruit may be well colored.
Before any pruning is done, however, it is essential to know the exact manner in which the trees or shrubs bear their fruits, for unless this is understood the operator may be working against his own interests and injuring the tree at the same time. For instance, apples and
pears bear their fruits upon gnarly twigs called spurs, the plum and cherry usually upon spurs, but sometimes also on the axial growths; the peach bears usually upon the axial growth of the previous season, but also to some extent upon spurs which live only two or three years as a rule; the quince bears upon terminal shoots of the present season; the grape upon shoots of the current season ; the raspberry and black berry usually upon shoots of the previous sea son, the shoots dying after production ; and the currant and gooseberry upon wood one or more years old. Further advantage may be taken of the method of fruit production in preventing the necessity of thinning, the fruit-buds being re moved by the cutting out of the fruit-bearing wood.
In the pruning of ornamental subjects the same principles apply. Except for removing straggling, unsightly or unnecessary growths, the pruning has mainly to do with flower pro duction. Flowering shrubs and trees may be divided into two groups; those which produce their flowers from buds which were matured during the previous season; and those whose buds are developed during the current year. The one rule that will apply to these subjects is: Prune after flowering. If members of the first group are pruned during the winter they will generally suffer severe loss of flower buds; members of the other group, however, should be pruned, preferably, in early spring about the time that growth starts. Properly done and at the right time the production of bloom should be greatly enhanced with each group.
There is considerable difference of opinion as to when subjects should be pruned, but if wounds are properly made, that is, close to the main stem without leaving any stub, and if the large ones are protected from decay during the healing process, they may be pruned at any time, preferably, perhaps, just before the season of most active growth when the object is wood, and after this period if the object is fruit. Trees grown as cordons, espaliers, etc., require the greatest skill, but these practices are largely matters of training and are of rare application in the United States.
There is an immense literature on the sub ject, consisting chiefly of short articles on spe cial phases, to be found in horticultural jour nals of this and foreign countries and in the publications of governmental departments of agriculture and of agricultural colleges and schools. For general treatment of the subject consult Bailey, L. H.