Pruning after the third winter.
For the pruner who understands the pruning of young vines and has brought them to approximately the form represented in Figs. [29] and [30], the subsequent winter pruning is very simple. It involves, however, one new idea—the distinction between fruit and sterile wood.
Up to the third winter pruning, this distinction is not necessary; first, because practically all the wood is fruit wood, and second, because the necessity of forming the vine controls the choice of wood. From this time on, however, this distinction must be carefully made. At each winter pruning a number of spurs of fruit wood must be left to produce the crop to be expected from the size and vigor of the vine. Besides these fruit spurs, it may be necessary to leave spurs of sterile wood to permit of increasing the number of fruit spurs the following year.
Fig. 31. Four-year-old vine pruned for vase-formed head.
This will be made clear by comparing Figs. [30] A and [31]. Figure [30] A shows a vine at the third winter pruning with two fruit spurs of two buds each and one fruit spur of one bud—five fruit buds in all.
If these five fruit buds all produce vigorous shoots during the following summer, they will supply five canes of fruit wood which can be used to form five fruit spurs at the following winter pruning, which will be about the normal increase necessary. Some of these fruit buds, however, may produce weak shoots or shoots so badly placed that they would spoil the shape of the head if used for spurs. Other shoots, however, will be produced from base, secondary and adventitious buds which, while less fruitful, can be used to form spurs for the starting of new arms.
