Occasionally rejuvenating old vines by pruning is worth while. When such an attempt is made, it is best to cut back severely at the winter-pruning, leaving two, three or four canes, depending on the method of training, of six, eight or ten buds. The amount of wood left must depend on the vigor of the plant and the variety. The success of such rejuvenation depends much on selecting suitable places on the old vine from which to renew the bearing wood. It requires good judgment, considerable skill and much experience to rejuvenate successfully an old vineyard by remodeling the existing top, and if the vines are far gone with neglect it is seldom worth while.
Sometimes old vines or even a whole vineyard can be rejuvenated most easily by grafting. This is particularly true when the vines are not of the kind wanted, and when the vineyard contains an occasional stray vine from the variety to which it is planted. Directions for grafting are given on [pages 45 to 50]. The grafted vine is readily brought into shape, under any of the several methods of training, by treating it as a young vine.
Plate XII.—Diana (×3/5).
CHAPTER IX
GRAPE-PRUNING ON THE PACIFIC SLOPE
The methods of pruning and training native grapes, discussed in the last two chapters, do not apply to the Vinifera grapes grown in the favored valleys of the Rocky Mountains and on the Pacific slope. As we have already seen, the Vinifera or Old World grape differs markedly in habits of growth from the American species so that it would not be expected that pruning which applies to the one would apply to the other types. The fundamentals, to be sure, are much the same and the different species of grapes are about equally subservient to the shears of the pruner, but while pruning to regulate fruit-bearing finds many similarities in Old and New World grapes, the training of the vines is radically different.
European practices in pruning and training Vinifera grapes are so many and so diverse that the first growers of this fruit in America were at a loss to know how to prune their vines. But, out of a half century of experience, American growers of Old World grapes have adapted from European practices and have devised to meet new conditions, methods which serve very well in the new home for this old grape. Since the culture of the Old World grape is centered in California, almost confined to that state, California practice may be taken as a pattern in pruning and training the vines of this species.