In relatively mild climates where winter protection is not essential, such as western New York, the river bluffs of Missouri, and in sections of the South, a modified system of high renewal training is practised in large vineyards. Three wires are used for the trellis, with the lower wire usually twenty inches above the ground. The renewal head is started on a tree-like stem at or near the lower wire, as shown in Fig. 73. It will be noticed that dd in the illustration are wood of the preceding year's growth which may be called long spurs of bearing wood of the preceding year's growth. It will also be observed that spurs for fruit-bearing are left on the short arms g and b. After growth
starts the fruit will form on the young shoots on the lower wire and between the lower and second wire. As growth extends from dd and the arms, it is tied to the upper wires.
At the next pruning the long spurs dd are cut away and their places are taken by other long shoots that have grown up from the arms.
Those who have some experience will realize at once that with this high renewal system no two vines will permit the formation of arms or stubs in the same position. The main essentials are the retaining of arms or stubs capable of starting new growth, and the annual renewal of the long spurs dd.
Fig. 73. - High renewal plan, vine pruned.
In starting young plantations on this plan, the cane is trained upright on a small stake, the second year to the lower wire, where it is caused to divide by pinching.
When the vines are fully established the arms or stubs are renewed or shortened every two or three years by starting new shoots direct from the old head. If this is not done the arms or stubs would soon get too long.