Leaving some shoots can be appropriate in certain situations. If the winegrower decides to leave a shoot on the vine, it will be with a precise, defined objective. For example, a shoot can be used to counter vine elongation in order to restart growth in an area closer to the trunk at the time of pruning and thus closer to the roots and the sap-conducting vessels. However, leaving such shoots is not without risk and requires careful attention.
It is also important to make sure that there is not a significant leafhopper threat in the vineyard. Shoots are the part of the vine that is most likely to be used as a hatching place for the eggs by the insect vector. Furthermore, leaving shoots can increase the phytosanitary risks of mildew outbreaks which can then spread more rapidly. In such cases, it is very important to reduce the vegetation close to the vine at row and inter-row level in order to delay the spread of these diseases as much as possible.
When the winegrower decides to preserve a shoot in order to create a new arm, it should ideally be placed in the axis of the row, thereby allowing easier management during subsequent operations in year N and N+1. Care must be taken of this shoot, possibly adding a marker to the vine to ensure that other operators present on the plot at other times do not remove it. It may be possible to tie it to the vine to indicate its value. Note that the replacement of an arm causes a substantial wound that can, if it is poorly maintained, be an open door to contaminations of fungal complexes responsible for Esca. Several precautions and methods can reduce this risk (See Winter pruning