Fruit-bearing may be augmented by bending, twisting or ringing the canes, since all of these operations diminish vegetative vigor. Ringing is the only one of these methods in general use, and this only for some special variety or special purpose, and usually with the result that the vigor of the vine is diminished too much for the good of the plant. Ringing is discussed more fully in Chapter XVI. _The manner of fruit-bearing in the grape._ Before attempting to prune, the pruner must understand precisely how the grape bears its crop. The fruit is borne near the base of the shoots of the current season, and the shoots are borne on the wood of the previous year's growth coming from a dormant bud. Here is manifested one of Nature's energy-saving devices, shoot, leaves, flowers and fruit spring in a short season from a single bud. In the light of this fact, pruning should be looked on as a simple problem to be solved mathematically and not as a puzzle to be untangled, as so many regard it. For an example, a problem in pruning is here stated and solved. A thrifty grape-vine should yield, let us say, fifteen pounds of grapes, a fair average for the mainstay varieties. Each bunch will weigh from a quarter to a half pound. To produce fifteen pounds on a vine, therefore, will require from thirty to sixty bunches. As each shoot will bear two or three bunches, from fifteen to thirty buds must be left on the canes of the preceding year. These buds are selected in pruning on one or more canes distributed on one or two main stems in such manner as the pruner may choose, but usually in accordance with one or another of several well-developed methods of training. Pruning, then, consists in calculating the number of bunches and buds necessary and removing the remainder. In essence pruning is thinning. _Horizontal_ versus _perpendicular canes._ An old dictum of viticulture is that the nearer the growing parts of the vine approach the perpendicular, the more vigorous the parts. The terminal buds, as every grape-grower knows, grow very rapidly and probably absorb, unless checked, more than their share of the energy of the vine. This tendency can be checked somewhat by removing the terminal buds, which also helps to keep the plants within manageable limits, but is better controlled by training the canes to horizontal positions. Grape canes are tied horizontally to wires to make the vines more manageable and to reduce their vigor and so induce fruitfulness; they are trained vertically to increase the vigor of the vine. _Winter-pruning._