With age, the side shoots (branches/'arms') on the main skeleton of the vine become increasingly gnarled as their ends get further and further away from the main trunk (Image 01). The annual pruning over many years leads to adhesions/knots in the wood which obstruct the sap flow, and often after 5-10 years, the side shoots become useless (Image 02). It is then rejuvenated with a water shoot arising close to the stem. This close-to-the-stem, usually vertical water shoot is shortened and future fruiting canes will grow from its basal buds (Image 03). If no water shoot grows from there, try the following: hit the spot with the metal back of the pruning shears (not too timidly!) where you want a water shoot to grow, either on the stem or the side shoot. This will bruise the spot and a water shoot may grow there...
If a side shoot has died and can no longer be salvaged, it is removed with a 2-3cm long stub. The other side shoots will initially fill the gap by being cane pruned, which also ensures that there will be sufficient "eyes" along the cordon. The cut surface, however, will lignify and cause a sap flow obstruction in the main skeleton. An accumulation of such sap flow obstructions means that at some stage the entire cordon needs removing and replacing with a new shoot. It is best to plan this rejuvenation ahead over about 2 -3 years.
