Grafting the grape is mainly confined during recent years to the parts of Europe and California where the varieties of the European species (Vitis vinifera) are grown. The destruction of vineyards by the phylloxera became a national calamity in France, and soon extended to Germany and the Pacific slope of the United States. After testing hundreds of plans for the destruction of this tiny insect, it was found that grafting the European varieties and their hybrids on stocks of our wild species (Vitis riparia) gave the best success, as this stock is less injured by this destructive louse. In the States east of the mountains it is also found beneficial to graft such hybrid varieties as Brighton, Salem, Lindley, and Wilder on phylloxera-resisting stocks. In some sections the Delaware also succeeds far better worked on Vitis riparia stocks.
Where young seedling stocks are used of our wild species, one of the surest and easiest methods is shown at Fig. 65. The earth is scraped away from the crown of the stock and the top of the cut-off crown is sloped upward as in whip-grafting (84. Root-grafting the Apple). In this slope a gash is cut as in whip-grafting, taking care not to split the stock. The scion has a wedge tongue, as shown in Fig. 65, with a part of the lower end stuck in the soil. No waxing is needed, but the soil is banked up to the top bud of the scion. This grafting is done before the sap starts in the spring.
As the lower end of the scion takes root it must be cut off, after the union has taken place, where the native root is desired.
In grafting above the ground on wild vines we have found the plan shown in Fig. 66 very successful. After the leaves are well started in the spring, wrap wire around the vine as shown between the nodes. Below and above gash the vine for the insertion of a scion wedged at both ends. After springing in the scion, secure it by tying as shown and wax the wounds made at points of insertion. The bud on the scion will soon start growth, and during the season the writer has had a growth of six or more feet from the scion bud without removing the top of the stock. Indeed, we have had the best success where the top has not been cut away until the next season, when the growth of scion is able to use all the sap flow. Roses, shrubs, and other vines can be safely grafted in this way early in the spring and the top cut away when growth begins.
Fig. 65.—Grape-grafting. (After Bailey.)
Fig. 66.—Top-grafting the grape. (After Hussman.)
Fig. 67. - Grape grafted low down with long scions. (After Bailey.)
The common commercial plan used in California on a large scale is quite as successful in the States east of the mountains. By this plan the ordinary cleft grafting (90. Top-working Old Trees) is practised, using scions fourteen inches long. If the established stock is not more than half to three fourths of an inch in diameter at the crown only one scion is inserted. But if an inch in diameter two scions are put in - one on each side, with the bark of stock and scion together, as shown in Fig. 67.
The use of the long scion or scions is to make use of the sap pressure from the established stocks. The long scions are tied to a small stake for support and are banked to the top bud. Long grafts thus inserted with fruit-buds, often, if permitted, ripen fruit the first year. I have had the best success with the long-scion system when dormant scions were inserted after the leaves of the stock had begun to expand and the first heavy sap pressure was over. The inarching (54. Propagating by Inarching) method practised for instruction in German school gardens is also worthy the attention of amateurs. Cuttings or plants are started around a cultivated vine trained on a stake. As the stocks grow upward on small stakes, a branch or shoot of the cultivated variety is inarched on the top shoot of the stock. This union is accomplished during the season of most active growth and new wood cell formation. When united the shoot of the cultivated variety is severed just below the point of union and the top of the stock just above it, giving a top-worked vine for planting where wanted.