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. [Illustration: 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. [Illustration: FIG. 29. Vine of Fig. 28 after pruning for vase-formed head.]