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Pruning grape vines


In no fruit crop does pruning play so important a part, as regards the quantity of fruit borne, as with the grape. In fact the manner of pruning employed determines to a very large extent the cost of maintaining a vineyard.

Certain styles of pruning require a large expenditure of money in the construction of supports or trellises and an equal outlay each season for tying, both early in the season and during the summer. Other systems require less expensive trellises, and little or no expenditure of time or money in spring and summer tying, thus making a very considerable difference in the cost of producing a good quantity of fruit.

In this connection two of the important systems used by grape growers will be described, namely, the Kniffen and the high-renewal system. The first named requires no system, a greater outlay for trellises than does the second, but permits of growing the crop with very much less summer tying than is required by the high-renewal system.

The Kniffen System
It will be noted that the long trunk employed in the Kniffen system carries the fruiting branches far above the ground. This permits the annual growth to fall from the supporting wires in a natural way without the necessity of tying. This constitutes the chief advantage of this system over any other employed m the eastern grape belt. Another slight advantage which the Kniffen system has over the high-renewal or the renewal system is that the fruits are farther from the ground and experience teaches are less liable to injury from mildew and rot. They are, also somewhat easier to spray, although there is comparatively little difference in this regard between the Kniffen and the high-renewal systems.

The Kniffen system, then, consists in the carrying of either one or two main trunks to the height of 3 to 5 feet above the ground; sometimes they are carried to the height of 6 feet or more. If two trunks are employed, one is carried 6 feet or more above the ground and the other about 18 or 20 inches lower. It is not desirable to attempt to make the two stories on a single trunk, as the laws of growth induce development at the extremity of the cane and therefore the set of branches which is lowest upon a common trunk makes little or no development, growth being confined almost entirely to the uppermost set of branches.

When two trunks are employed, however, the case is different and each set of branches becomes, as it were, terminal branches, and a much more satisfactory growth results. The method of renewal employed in the Kniffen system is practically the same as that in the high-renewal system; that is, the canes which are to bear the fruit during the next season are selected from wood which developed the previous year. These canes are cut back to six or eight buds and are tied to the central wire of the overhead trellis. At the close of the season the bearing cane is removed and a new shoot, one developed from near the head of the trunk, is used to replace it during the succeeding year.

The same treatment is employed for the other side of the head; that is, the T-head at the top of the trunk on the Kniffen-trained vine serves the same purpose as the T-head - at the top of the trunk of the high-renewal vine.

The High-Renewal System
The high-renewal system of training requires requires a trellis consisting of three or more wires or other suitable supports carried by posts or stakes placed at convenient distances apart in the row of grapevines, the vines themselves being planted 8 or 10 feet apart in the row. The first or lowest wire upon the trellis is usually 18 or 20 inches from the ground. The next is about 18 inches higher, and the third about 2 feet still higher. The main trunk of the vine is carried to the height of the lowest wire or support. From it a cane carrying about eight buds is trained in either direction along the lowest wire.

From, each of these buds shoots develop which bear the crop of the season; but as these shoots are seldom able to care for themselves they must be tied to the upper supĀ­ports of the trellis. It will be noted from this that the summer tying of plants trained on, this system is very much greater than with plants trained on the Kniffen system. From the T-head, which, as has been stated, is carried to the height of the lowest wire, canes are carried in both directions along the lowest wire and are firmly tied to it.

Near the base of each of these canes, but upon the older wood of the T-head, short spurs carrying two or three buds are maintained, from which shoots develop which, in turn, are usually employed to furnish the fruiting canes of the succeeding year; that is, the spurs are the means of renewing the fruiting wood of the vine grown on the high-renewal system. The same plan can be and frequently is employed with the Kniffen system.