Ringing Grape Vines

The ringing of woody plants is a well-known horticultural practice.

Three objects may be attained by ringing: unproductive plants may be

brought into bearing by ringing; the size of the fruits may be

increased and thereby the plants be made more productive; and the

maturity of the fruit may be hastened. In European countries, ringing

has long been practiced with all tree-fruits and the grape, but in

America the operati n is recommended only for the apple and the grape

and with neither fruit is ringing widely practiced. Experiments

carried on at the New York Agricultural Experiment Station by Paddock,

as reported in Bulletin 151 from this Station, show that ringing may

well be practiced by grape-growers under some conditions. Since

Paddock's experiments, and possibly to some extent before, the grape

has been ringed to produce exhibition fruits or a fancy product for

the market.



Ringing consists in taking from the vine a layer of bark around the

vine through the cortex and bast of the plant. The width of the wound

varies from that of a simple cut made with a knife to a band of bark

an inch in diameter. The operation is performed during that period of

growth in which the bark peels most readily from the vine, the period

of greatest cambial activity. The term "ringing" is preferred to

"girdling," a word sometimes used, since the latter properly

designates a wound which extends into and usually kills the plant.



The theory of ringing is simple. Unassimilated sap passes from the

roots of the plant to the leaves through the outer layer of the woody

cylinder. In the leaves this raw material is acted on by various

agents, after which it is distributed to the several organs of the

plant through vessels in the inner bark. When plants are ringed, the

upward flow of sap is continued as before the operation, but the newly

made food compounds cannot pass beyond the injury, and therefore the

top of the plant is supplied with an extra amount of food at the

expense of the parts below the ring. The extra food produces the

results noted.



It turns out in practice that ringing is usually harmful to the plant,

as one might expect from so unnatural an operation. Injury to the

plant arises from the fact that parts of the vine are starved at the

expense of other parts; and because, when the bark is removed, the

outer layers of the woody cylinder dry out very quickly and thus check

to some extent the upward flow of sap through evaporation from the

exposed wood. Thus, not infrequently, the plant's vitality is

seriously drained. Nevertheless, vineyards may be found in which

ringing has been extensively practiced many seasons in succession and

which continue to yield profitable crops, the growers having learned

to perform the work of ringing so as to injure the vines but little.



Ringing without harm to the plant depends much on the way in which the

vines have been pruned. For instance, if the vines are pruned to the

two-arm Kniffin method, the ringing of bark should be done from both

arms just beyond the fifth bud. Thus, the ten buds left on the vine

produce enough leaf surface to supply the food necessary to keep the

vine in vigorous condition. When the four-arm Kniffin method is used,

the two top arms only are ringed, and even so three or four buds must

be left on each for renewals. Whatever the method of training, it will

be seen from these examples that some unringed wood must be left to

the vine with which to supply leafy shoots to support the vine. Some

growers ring their vines only every other year, thus giving them an

opportunity to recover from whatever loss of vigor they may have

sustained in the season of ringing.



Several other considerations are important in ringing: First, the

vines must not be permitted to carry too large a crop. Again, the

amount of fruit on the ringed portion of the vine must depend on the

amount of leaf surface not only of the plant but of the ringed arms,

each ringed arm acting somewhat independently so far as its crop is

concerned. If too many clusters are left on the ringed arms, it always

follows that the fruit is inferior and often worthless. Lastly, all

fruit between the rings and the trunk must be removed, for it does not

mature properly and so adds only to the drain on the plant's vitality.



As to the results, it is certain from the experiments that have been

conducted and from the experience of grape-growers, that the maturity

of the fruit is hastened, and berries and bunches are larger when the

ringing has been done intelligently. Many growers hold that fruit

produced on ringed vines is never quite up to the mark in quality and

in firmness of fruit. There seems to be a difference in opinion about

this falling off in quality, however, although unquestionably, choice

sorts, as Delaware, Iona and Dutchess, suffer more or less in quality.

It is commonly agreed, also, that varieties, the fruits of which crack

badly, as the Worden, suffer more from cracking on ringed than on

unringed vines.



Experiment and experience prove that the best results of ringing are

obtained if the work is done when the grapes are about one-third

grown. Of course the exact time depends on the season and on the

variety. The operation is variously performed and is easily done with

a sharp knife, but when large vineyards are to be ringed the grower

ought to provide himself with some simple tool. Paddock, in the

bulletin previously mentioned, pictures two of these tools and these

are reproduced in Fig. 52.




1 and 2; while 3 and 4 show ringed vines at the beginning and the

close of the season.]



In conclusion it must be said that it is doubtful whether the gains

attained by ringing offset the losses. The practice is chiefly of

value only when exhibition clusters of grapes are wanted or when it is

necessary to hasten the maturity of the crop. Always, however, the

work must be performed with intelligence and judgment or the losses

will offset the gains.