Manual of American Grape-Growing. U. P. Hedrick
struck root and became independent, whereupon the stock dies or becomes so moribund that the beneficial effects are lost. There are grape-growers who argue that it is beneficial to the vine to have roots from both stock and cion, but experience and experiments very generally teach the contrary, it being found that in most grafts the cion roots grow more vigorously than stock roots and eventually starve out the latter. The disastrous effects of cion-rooting are often to be found, also, when grafting has been done on old vines in the vineyard; and, again, when the graft is too close to the root system.
Another cause of failure is that different stocks require that the vineyard soil be treated differently, especially at planting time. Vulpina stocks require that the soil be much more deeply plowed than for Viniferas on their own roots, since Vulpinas are deep-rooted and are exacting in the depth of root-run required. Those who have had most experience with resistant stocks maintain that all American grapes require rather deeper plowing than European grapes on their own roots.
Influence of the Stocks on the Cion
Up to the present, the growing of grafted grapes has been carried on with little thought of the mutual influence of stock and cion; grapes have been grafted only to secure vines resistant to phylloxera. Yet there can be no doubt that stock and cion react on one another, and that any variety of grapes is influenced for better or worse in characters of vine and fruit by the stock upon which it is grafted. A plant is a delicate mechanism, easily thrown out of gear, and all plants, the grape not the least, are more or less changed in the adjustments of stock and cion. One could fill a large volume on the supposed reciprocal influence of stock and cion in fruits. Space suffices, here, however, to mention only those proved and those having to do with the influence of the stock on the cion when the grape is grafted.
Influence of stocks on European grapes summarized.
Common experience in Europe and California indicates that varieties of Vinifera grapes grafted on resistant stocks which are perfectly adapted to soil and climate produce not only larger crops but sweeter or sourer grapes; that the crop ripens earlier or later; that the vine is often more vigorous; and that there are some minor differences depending on the stock used. Wine-makers assert that the character of their product may be affected for better or worse by the stock. Often vines are so improved by grafting that the extra expense of the operation and of the stock is paid for; although, to be sure, about as often the effects are deleterious. The successes and failures of vineyards on resistant stocks make plain that the vine-grower must study the many problems which stocks present and exercise utmost intelligence in the selection of the proper stock.
Influence of stocks on American grapes.
No doubt American species of grapes may be as profoundly modified by stocks as the European species, but there is but little evidence on this phase of grape-growing to be drawn from the experience of vineyardists. One rather conclusive experiment, however, shows that American grapes may be improved by growing them on stocks which give them better adaptations to their environment. The experiment was tried in the Chautauqua grape-belt in western New York by the New York Agricultural Experiment Station. The test was carried on for eleven years, during which time many interesting possibilities in grafting grapes in this region came to light. It was proved that the stock materially affects the vigor and productiveness of the vine and the quality of the grapes. The following brief account is taken from Bulletin No. 355 of the New York Station:
In this experiment a number of varieties were grafted on St. George, Riparia Gloire and Clevener stocks, and a fourth group on their own roots. The varieties grafted were: Agawam, Barry, Brighton, Brilliant, Campbell Early, Catawba, Concord, Delaware, Goff, Herbert, Iona, Jefferson, Lindley, Mills, Niagara, Regal, Vergennes, Winchell and Worden. The planting plan and all of the vineyard operations were those common in commercial vineyards.
Yearly accounts of the vineyard show that the vines passed through many vicissitudes. The experiment was started in 1902 when St. George and Riparia Gloire stocks from California were set and grafted in the field. Many of these died the first year. The winter of 1903–04 was unusually severe, and many more vines were either killed or so severely injured that they died during the next two years. The vines on St. George, a very deep-rooting grape, withstood the cold best. Fidia, the grape root-worm, was found in the vineyards early in the life of the vines and did much damage in some years. In the years of 1907 and 1909 the crops were ruined by hail.
But despite these serious setbacks it was evident throughout the experiment that the grafted grapes made better vines and were more productive than those on their own roots. As an example of the differences in yield, a summary of the data for 1911 may be given. In this year, an average of all the varieties on own roots yielded at the rate of 4.39 tons to the acre; on St. George, 5.36 tons; on Gloire, 5.32 tons; on Clevener, 5.62 tons. The crops on the grafted vines were increased through the setting of more bunches and the development of larger bunches and berries.
The grapes on the vines grafted on Gloire and Clevener ripened a few days earlier than those on their own roots, while with St. George a few varieties were retarded in ripening. Changing the time of maturity may be very important in grape regions where there is danger of early frost to late-ripening sorts, and where it is often desirable to retard the harvest time of early grapes.
In the behavior of the vines, the results correspond closely with those given for yields. In the growth ratings of varieties on different stocks, the varieties on their own roots were rated in vigor at 40; on St. George, at 63.2; on Gloire, at 65.2; on Clevener, at 67.9. There is no way of deciding how much the thrift of the vines depends on adaptability to soil, and how much on other factors. Since all of the varieties were more productive and vigorous on grafted vines than on their own roots it may be said that a high degree of congeniality exists between the stocks and varieties under test.
The experiment suggests that it would be profitable to grow fancy grapes of American species on grafted vines, and that it is well within the bounds of possibility that main-crop grapes can be grafted profitably. In the general tuning-up of agriculture now in progress, it may be expected that soon American as well as European varieties of grapes will be grown under some conditions and for some purposes on roots other than their own.
Direct Producers
Attempts innumerable have been and are still being made to secure, by hybridizing V. vinifera and American species of grapes, varieties that will resist phylloxera, the mildew and black-rot. The grapes of this continent are relatively immune to all of these troubles, and if hybrids could be obtained to produce directly, without grafting, grapes with the good qualities of the Viniferas—in short, European grapes on American vines—the cultivated grape flora of the whole world might be changed. So far, a "direct producer" that is wholly satisfactory in either Europe or California has not been found for the wine or raisin industries, although a number of varieties are rated as very good table grapes, and a few are used in wine-making. The best of the direct producers are Lenoir, Taylor, Noah, Norton's Virginia, Autuchon, Othello, Catawba, and Delaware.
CHAPTER V
THE VINEYARD AND ITS MANAGEMENT
A vineyard is more artificial than other plantations of fruits, since the vine requires greater discipline under cultivation than tree or bush. Yet greater art is required only when the attempt is made to grow the grape to perfection, for the vine bears fruit if left to indulge in riotous growth wheresoever it can strike root. Vineyard management, therefore, may represent the consummate art of three thousand or more years of cultural subserviency; or it may be so primeval in simplicity