_The True or Four-Cane Kniffin System._--Figure 21 shows the true Kniffin system, very nearly as practiced by its originator. A single stem or trunk is carried directly to the top wire, and two canes are taken out from side spurs at each wire. Mr. Kniffin believed in short canes, and cut them back to about six buds on both wires. But most growers now prefer to leave the upper canes longer than the lower ones, as seen in illustration. The bearing shoots are allowed to hang at will, so that no summer tying is necessary; this is the distinguishing mark of the various Kniffin systems. The main trunk is tied to each wire, and the canes are tied to the wires in spring. This system possesses the great advantage, therefore, of requiring little labor during the busy days of the growing season; and the vines are easily cultivated, and if the rows are nine or ten feet apart, currants or other bush-fruits can be grown between. The system is especially adapted to the strong varieties of grapes. For further comparisons of the merits of different systems of training, the reader should consult Chapter II. [Illustration: 21. THE TRUE KNIFFIN TRAINING.] [Illustration: 22. NO. 21 WHEN PRUNED.] The pruning of the Kniffin vine consists in cutting off all the wood save a single cane from each spur. Fig. 22 illustrates the process. This is the same vine which is shown with the full amount of wood on in fig. 21. The drooping shoots shown in that illustration bore the grapes of 1892; and now, in the winter of 1892-93, they are all to be cut away, with the horizontal old canes from which they grew, save only the four canes which hang nearest the main trunk. Fig. 22 shows the vine after it had been pruned. It is not obligatory that the canes which are left after the pruning should be those nearest the trunk, for it may happen that these may be weak; but, other things being equal, these canes are preferable because their selection keeps the old spurs short. The careful grower will take pains to remove the weak shoots which start from this point, in order that a strong cane may be obtained. It is desirable that these side spurs be removed entirely every three or four years, a new cane being brought out again from the main body or trunk. There is little expectation, however, that there shall be such a complete renewal pruning as that practiced in the High Renewal, which we discussed in the last chapter.