In neglected vineyards where pruning has not been done for several years, several strategies can be employed. One is to completely remove the old cordons except for a six inch renewal spur at the head of each cordon. Allow new shoots to grow down the wire to form the new cordon. Pinch them when they reach the desired length.
The second option is to cut the growth on one side of the vine (left side) back to two to four buds of the previous season’s growth. On the other side of the vine (right side) cut off all the lateral growth leaving just a naked cordon. This will allow the left side of the vine to produce fruit. The second season, bring the right side of the vine into production and cut the left side back to a naked cordon. In the third season the vine is completely rejuvenated and back to near full production.