6. A NEWLY SET VINEYARD.
When to Prune.—Grape vines may be pruned at any time during the winter. It is the practice among most grape-growers in the north to prune as time permits from November to late in February, or even early March. The sap flows very freely from cuts made in spring and early summer, causing the phenomenon known as "bleeding," or in Europe as "weeping," and in order to prevent this loss, pruning is stopped six weeks or more before the time at which the buds usually swell. It is yet a moot point if this bleeding injures the vine, but it is a safe practice to prune early. The vine is cut off an inch or two beyond the last bud which it is desired to leave, in order to avoid injury to the bud from the drying out of the end of the cane.
The pruning is done with small hand pruning-shears. The canes are often allowed to remain tied to the wires until the pruning is accomplished, although it is the practice with most growers who use the Kniffin system to cut the strings before pruning. The removal of the severed canes is known as "stripping." In large vineyards, the pruner sometimes leaves the stripping to boys or other cheap labor. The stripping may be done at any time after the pruning is performed until spring. It must be done before the growth starts on the remaining portions of the vine, however, to avoid injury to the young buds when tearing the vines off the trellis.
Summer Pruning.—There is much discussion as to the advisability of summer pruning. It is essential to the understanding of the question that the grower bear in mind that this summer pruning is of two kinds—the removal or "breaking out" of the superfluous shoots, and heading-in or "stopping" the main canes to keep them within limits. The superfluous shoots are such as spring from small, weak buds or those which break from the old arms or trunk of the vine. Shoots which start from the very base of the old cane are usually weak and should be removed. Buds in this position are shown at a a, in [fig. 4]. The secondary or axillary branches, which often start from the base of the season's shoots, should be removed or broken out. These superfluous shoots are pulled off from time to time as they appear, or the buds may be rubbed off before the shoots begin to grow.
The heading-in of the main canes, while desirable for the purpose of keeping the vine within bounds, is apt to cause a growth of laterals which choke up the vine and which do not mature, and in those styles of training in which very little wood is allowed to grow, the practice may prevent the development of a sufficient amount of leaf surface to properly sustain the vine. Vines are often weakened by summer pruning. These dangers can be overcome by careful attention, however, especially by heading-in very lightly and by doing it as late in the season as possible, when new lateral growth does not start readily. The necessity of much heading-in has been largely obviated in late years by the adoption of high or drooping systems of training, and by setting the vines far apart. The strong varieties, like Concord, Brighton and Niagara, should be set ten feet apart in the row, especially if grown upon the Kniffin system. Catawba, being a very upright grower and especially well adapted to upright training, may be set eight feet apart, and Delawares are often set as close as six or eight feet. It is doubtful, however, if any variety should be set less than eight feet apart for trellis culture. In Virginia and southward, where the growth is large because of the long seasons, vines are often set more than ten feet apart. In the South, the rows should run north and south, that the fruit may be shaded from midday sun. The only summer heading-in now generally recommended is the clipping of the tips when they fall over and begin to touch the ground. This clipping is often done with a sickle or sharp corn-cutter.
Objects of Pruning.—The objects of pruning the grape, as of other fruits, are five:
1. To produce larger and better fruit.
2. To maintain or augment the vigor of the vine.
3. To keep the vine within manageable limits.
4. To facilitate cultivation.
5. To facilitate spraying.