cleft grafting, a popular method for changing vine variety in the vineyard (see top grafting). The severing of the trunk may be at ground level or just below the head; the latter is preferred because desuckering is simpler, less vine training is required, and the extra wood of the trunk aids the rapid establishment of the new vine. The trunk is cut horizontally in early spring and the stump split across the middle to about 5 cm/2 in depth. scion pieces of one or two nodes are prepared from dormant canes with a long-tapered wedge. After the trunk is split and spread, the pieces are inserted one on each side so that cambiums of rootstock and scion are matched to facilitate their bonding. The wounds are sealed with grafting mastic, then with paint. notch grafting is an alternative. See diagram.