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 de icate 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.