Fig. 52. Tools used in ringing grape-vines are shown in 1 and 2; while 3 and 4 show ringed vines at the beginning and the close of the season.
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].
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.