As the wood becomes weak and the life span shortens, if grapes are infested with insects that absorb nutrition from the roots, seedlings are formed and grapes are cultivated using a special type of vine root stock that prevents the insects from absorbing the nutrition.
The Katsunuma Tomimachi grape is called “Koryu,” which has withstood many natural disasters prior to being used as a root stock, and even now it produces magnificent and abundant grapes.