Screw grafting: what it is
Grafting of the vine is an agronomic technique designed to create new specimens using a rootstock and a graft. The first is the basal part on which the graft is arranged to give life to a new specimen. This technique is able to develop a plant with the same genetic characteristics as the grafted one. This practice is very important because it is able to improve the variety, saving it, as happened long ago, from very harmful epidemics. It is good to know that the grafts can only be implemented on woody or semi-woody specimens such as the vine. There are countless techniques for making grafts, in fact, in some, not only the graft and rootstock are used but also the intermediary. In general, the rootstock and the graft (consisting of a branch of the mother plant or one of its buds) are cut in such a way as to make them match and allow their fusion which will lead to the birth of a new plant from two different specimens. Before implementing this technique, it is necessary to choose the right season which coincides with spring or the end of the summer season.
Variety to graft
Before proceeding with the grafting of our plant, it must be made aware that not all species can be grafted. Specimens born from other grafts cannot be used for this practice. The wild vine (European and American), on the other hand, is very suitable, where the American one is used as rootstock, which has proved to be very resistant to phylloxera, while the European variety is used as a graft from which grapes and wine are obtained. It is good to know that grafting cannot be practiced between an American and a Canadian specimen (the latter variety has an exclusively ornamental function). The latter also propagates by seed, offshoot or cutting. With regard to grafting techniques, you can choose from the following grafts: triangle, double and simple English split, zeta, bridge, Majorcan, eye, scudetto, splinter and star. According to the type chosen, the multiplication of the vines takes place from the end of the winter season to the end of the summer one.
Split screw connection
The graft of the split vine belongs to the category of woody grafts since the split is practiced in the woody part of the rootstock. This technique is suitable for those more vigorous branches of adult plants. We talk about simple or double English split. With the first, the radius of the trunk of the rootstock is cut, in which the scion (or graft) is positioned, consisting of a branch containing 2 or 3 buds. With the double English split, on the other hand, a cut is made in the whole diameter of the rootstock trunk and then positioning the shoots containing always between 2 or 3 buds. It is good to be aware that the cuts are made with a knife suitable for grafting, the scions must have been taken during normal winter pruning. All the elements necessary for the implementation of the graft of the vine must be healthy, free from infections and injuries. It is good to know that the grafting does not end with the scion matching the rootstock, it is necessary to wrap around this new structure some adhesive paper and mastic, and possibly a lace in order to hold the graft in place.
Eye screw connection
The grafting of the eye vine is also called a scudetto or a bud, and is used for the multiplication of fruit and ornamental trees. It is good to know that with this practice the same results as split grafting are not achieved, as the graft consists of a bud cut from young and vigorous branches. Before proceeding, it is necessary to have a disinfected knife suitable for the practice of grafting cuts, a bud and a healthy rootstock. At this point, a T-shaped cut is made in the bark of the rootstock (the dimensions of the latter must not exceed approximately one and a half centimeters), the two flaps are lifted and the bud that was taken during the month of July is placed; ends with wrapping the mastic or plastic around the graft, in order to facilitate the germination of the new plant.
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