Manual of American Grape-Growing Part 15

The vine so pruned consists of a single cane which with the older wood at the base reaches nearly to the top of the stake, or fifteen inches.

This if properly treated will develop into a vine with a trunk of about twelve inches, though this length can be modified slightly, as will be explained later.

This cane consists of about seven or eight joints or internodes, with an equal number of well-formed eyes and an indefinite number of dormant buds, princ.i.p.ally near the base of the cane or junction of the one- and two-year-old wood. Only the buds on the upper half of this cane will be allowed to grow. These buds--about four--should give six to eight bunches of grapes and four, six, or eight shoots from which to form the spurs at the following winter pruning.

With a vine which has been cut back to form a high head, the cane is about twenty-four inches long and can be used to form a trunk eighteen inches high, though this height can be modified as in the last case.

As with the shorter cane, only the buds on the upper half will be allowed to produce shoots. These--about six--should give ten to twelve bunches and the shoots necessary for the formation of spurs.

In all cases a full internode has been left above the top bud. This is done by cutting through the first bud above the highest which it is desired to have grow. This cut is made in such a way as to destroy the bud but to leave the diaphragm intact and part of the swelling of the node. This upper internode is left partly to protect the upper bud, but princ.i.p.ally to facilitate tying. By making a half-hitch around this internode, the vine is held very firmly. If the swelling at the node of the destroyed bud is not left, many vines will be pulled out of the hitch when they become heavy with leaves and supple with the flow of sap in the spring.

In tying the vines, no turns or hitches must be made around any part except this upper internode. A hitch below the top bud will result in a crook-necked vine, as the top will bend over in the summer under the weight of the foliage. A hitch lower down is even more harmful, as it will girdle and strangle the vine.

A second tie about half way from the upper to the ground is always necessary to straighten the cane. Even if the cane is straight when pruned, a second tie is needed to keep it from curving under the pressure of leaves and wind in the spring. For high-headed vines three ties are usually necessary.

For the top tie, wire is particularly suitable. It holds better than twine and does not wear. Even though it is not removed, it does no harm, as the part around which it is wound does not grow. The lower ties should be of softer material, as wire has a tendency to cut into the wood. They should be placed so that the cane is able to expand as it grows. With thin and especially with round stakes this means that the tie must be loose. With large, square stakes there is usually sufficient room for expansion, even when the twine is tied tight.

_Third summer pruning._

During the third season, average well-grown vines will produce their first considerable crop and develop the canes from which will be formed the first arms.

Such a vine, soon after the starting of the buds in spring, will have one vigorous shoot about three inches long grown from the old wood and five fruit buds started above on the cane. All the buds and shoots below the middle of the cane should be removed.

This will leave the four or five fruit buds and will give the vine the opportunity to produce eight or ten bunches of grapes. These buds will produce also at least four or five shoots. If the vine is very vigorous and the season favorable, they may produce eight, ten or more.

When the five shoots grow, the height of the head will be determined at the next winter pruning by which of the corresponding canes are left as spurs. If the highest two canes are cut back to spurs and all others removed, the vine will be headed as high as possible, as these two spurs form the two first arms which determine the length of the trunk. If the lowest two canes are chosen and all of the vine above them removed, the trunk will be made as low as possible. Intermediate heights can be obtained by using some other two adjacent canes and removing the rest. It is often advisable to leave some extra spurs lower than it is desired to head the vine and to remove these lower spurs the following winter after they have borne a crop. For example, the three or four upper canes might be left, if the vine is vigorous enough, and the lowest one or two of these removed at the next pruning. This, however, is not often necessary with properly handled vines and is objectionable because it makes large wounds in the trunk.

_Third winter pruning._

At the end of the third season's growth the vine should have a straight, well-developed trunk with a number of vigorous canes near the top from which to form the arms.

Figure 28 represents a well-grown vine at this period. No shoots have been allowed to grow on the lower part of the trunk and the five buds allowed to grow above have produced nine vigorous canes. The pruner should leave enough spurs to supply all the fruit buds that the vine can utilize. The number, size and thickness of the canes show that the vine is very vigorous and can support a large crop. It will depend somewhat on the variety how many buds should be left. For a variety whose bunches average one pound, and which produces two bunches to the shoot, twelve fruit buds should give about twenty-four pounds, or about seven tons per acre, if the vines are planted 12 by 6 feet, as these were. The number of spurs will depend on their length. Six spurs of two buds each will give the required number, but as some of these canes are exceptionally vigorous they should be left a little longer, in which case a smaller number of spurs will suffice.

[Ill.u.s.tration: FIG. 28. Three-year-old vine ready for pruning.]

When the number and length of the spurs are decided on, the canes should be chosen which will leave these spurs in the most suitable position for forming arms. This position will depend on whether we want a vase-form or fan-shaped vine. In the first case, we choose those which will distribute the spurs most evenly and symmetrically on all sides, avoiding any which cross or point downwards.

In the second case, we choose only those canes which run in the direction of the trellis, avoiding canes which stick out between the rows. Downward pointing canes may be used in this case.

[Ill.u.s.tration: FIG. 29. Vine of Fig. 28 after pruning for vase-formed head.]

Figure 29 shows the vine after pruning for a vase-formed head. The pruner has used two of the strongest canes to form two three-bud spurs and three of medium vigor to form three two-bud spurs. The head is of good shape, though some of the spurs are a little too low. One, two, or three of these can be removed at the following winter pruning, and the permanent arms and head of the vine formed from canes which develop on the two highest spurs. If the vine were too high, the head could be developed the next year from the three lowest spurs and the upper part removed.

[Ill.u.s.tration: FIG. 30. Three-year-old vines: _A_, pruned for a vase-formed, and _B_, for a fan-shaped head.]

Figure 30 shows vines of the same age of practically perfect shape.

Less spurs have been left because the vines were less vigorous. It is easier to properly shape vines which make only a moderate growth during the first three seasons. On the other hand, very vigorous vines can finally be brought into practically perfect shape and the somewhat larger and more numerous wounds necessary are more easily healed by a vigorous vine.

_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.

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 advent.i.tious buds which, while less fruitful, can be used to form spurs for the starting of new arms.

[Ill.u.s.tration: FIG. 31. Four-year-old vine pruned for vase-formed head.]

Figure 31 shows a vine after the fourth winter pruning which had developed from a vine similar to that shown in Fig. 30 A. From the three fruit spurs left the previous year four canes have been chosen for the fruit spurs of this year. The old spur on the left has furnished two new spurs and the two old spurs at the right each one new spur. The pruner, judging that the vine is sufficiently vigorous to stand more wood, has formed two spurs from water sprouts which, while not likely to produce much fruit the first season, will supply fruit wood for the following year. The result is a very well-shaped vine with six almost perfectly balanced spurs. These spurs will develop into permanent arms, some of them furnishing finally two or three.

Figure 32 shows a high-headed vine of the same age. It has five spurs, of which four are fruit spurs and one a spur of sterile wood left to shape the vine. The two more or less horizontal spurs on the right will bear fruit the following autumn and will be removed entirely at the following winter pruning, as they are badly placed. The arms of the vine will then be developed from the three upright spurs, which are excellently placed.

[Ill.u.s.tration: FIG. 32. Four-year-old vine pruned for high vase-formed head.]

Each year thereafter the same process must be followed. First, enough fruit spurs, as well placed as possible, must be left to produce the crop. Second, on most vines supplementary spurs of sterile wood must be left to supply more arms where they are needed, and finally, when the full complement of arms has developed, to supply new arms to replace those which have become too long or are otherwise defective.

_Fan-shaped vines._

With headed vines, the treatment up to the third winter is the same except for the variations in the height of the head. At the third winter pruning, however, the formation of the head commences, and the pruner determines whether it shall be vase-formed or fan-shaped. The production of a vase-formed head has already been described.

At the third winter pruning, the vine should be pruned to two spurs, as shown in Fig. 30 B. More vigorous vines should _not_ be given more spurs, as in Figs. 29 and 30 A, but the spurs should be made longer, with four, five, or even six eyes in some cases. This is in order to obtain some fruit, which might not be obtained from long pruning varieties by leaving many spurs. With extremely vigorous vines one fruit cane may be left at this pruning. The wires of the trellis should be put up this year, if this has not already been done.

Fig. 33 A and 33 B ill.u.s.trates the second step in the production of a fan-shaped head. This form of head is used only for trellised vines and long-pruned varieties. The formation of the head and the management of the fruit canes are therefore conveniently discussed together.

[Ill.u.s.tration: FIG. 33. _A_, before pruning; _B_, after pruning.]

By comparing the pruned vine, Fig. 33 B, with the unpruned, Fig. 33 A, the method of pruning will be made clear. The unpruned vine shows two arms, the spurs of the previous year, from one of which have grown three vigorous canes and from the other two somewhat less vigorous.

The pruned vine shows a complete unit, that is, a fruit cane with its accompanying renewal spur on the vigorous side and a spur for the production of fruit wood for the following year on the other side. If the vine had been more vigorous two complete units would have been left and one or two extra spurs.

As the form of the vine is determined by the renewal spurs, special attention should be paid to their position. In this case, the middle cane on one arm and the lower cane on the other have been used for renewal spurs. This brings them both to the same height above the ground and determines the place of the permanent arms. The next year each of these spurs will furnish a fruit cane and one or two renewal spurs. The arms will thus in two or three years be increased to four, or, with very large vines, to six. These spurs should be chosen as nearly as possible in the plane of the trellis, that is, they should not project out sideways. Figure 25 shows vines of this kind of full size and in full bearing.

The fruit canes also should be as nearly as possible in the direction of the trellis, though this is not so important, as they can be bent over to the wire when tied up, and in any case they are removed the next year.

_Double-headed vines._

Some growers attempt to arrange the arms of their vines in two stages, one above the other, forming double-headed or two-crowned vines. The method is applied to both vase-formed and trellised vines. It is open to the same criticisms as the vertical cordon, the chief of which is that it cannot be maintained permanently. The lower head or ring of arms finally becomes weak and fails to produce wood.

It is easier to maintain in trellised vineyards and has some advantages, the chief of which is that it makes it easier to keep the vine in the single plane and to prevent arms getting into the inter-rows. The double trunk is not necessary and is, in fact, a disadvantage, as one trunk has a tendency to grow at the expense of the other.

_Vertical and bowed canes._

Figure 24 A shows a long-pruned vine in which the fruit canes have been tied vertically to a tall stake. This is a method used commonly in many vineyards. The unit of pruning is the same as in the method just described, consisting of a fruit cane and a renewal spur. The framework of the vine consists of a trunk of medium height, with a vase-formed head consisting of three or four arms. The defects of this system have been pointed out on page 155.

It is used with fair success with seedless Sultanas and with some wine grapes such as Colombar, Semillon, Cabernet, and Riesling, in the hands of skillful pruners. The results with Sultanina are very unsatisfactory.