The VinPro (SA) Consultation Service publication "Guide for establishing a vineyard" provides comprehensive guidelines for the development of young vines while "Wingerdbou in Suid-Afrika", pp. 202 - 233 covers winter pruning of adult vines. A video entitled "Wintersnoei" is also available from VinPro (SA) Consultation Service.
Pre-pruning, which involves pruning the shoots of trellised vines 30 - 40 cm from the base, is done to distribute labour more evenly and speed up the final pruning process.
Clean pruning entails the removal of all the shoots, except the bearers, and should be done by well-trained labourers, since this influences the most important aspects such as vine shape and number of buds.
Final pruning later in the season limits the bearer shoots mostly to 2 buds.
Pre- and clean pruning should preferably only be applied to vigorously growing vines and early cultivars.
Delay pruning if the soil and air are very dry to prevent drying out of pruning wounds. Do not prune during rainfalls either, because free water is conducive to fungal infections in pruning wounds.
Young vines in the vine development stage should be pruned by the most experienced persons seeing that each vine has to be judged individually in order to obtain optimum shape. The tempo and method of vine development are determined by vigour and trellis system and are discussed in full in the "Guides for establishing a vineyard".
The pruning system must be adjusted to the cultivar and location. Since most of the wine grape cultivars have basal buds that are sufficiently fertile, pruning is done with 2 bud bearers (short cut). Exceptions are less fertile cultivars such as Sultana, as well as infertile locations where either the semi-long cut (4 - 6 buds) or the long cut (+ 8 buds) is applicable. For each semi-long or long bearer a short bearer should always be left in place to prevent build up of bearers.
In frost free regions as well as with cultivars that set normally, final pruning may already take place at the end of the month. In areas where frost occurs regularly, final pruning should be undertaken much later in order to delay the budding of the bearer buds.
In cultivars such as Hanepoot which are susceptible to drooping or poor set, clean and final pruning should be undertaken very late and as one action when the shoot tips have already started budding.
Cultivars that are susceptible to delayed budding should also be clean pruned and final pruned in one stage as late as possible.
Regarding the number of bearers that are left per vine, a standard recipe may be followed, namely an increase of one bearer in the case of vigorous growth and a decrease of one bearer in the case of weak growth, or by making use of 1 bud bearers instead of 2 bud bearers.
When long bearers are used in addition to short bearers in vigorously growing vines, the position of the long bearers on the cordon should be changed annually so that the short bearers may become equally strong.
In trellised vines the cordon arm should not be twisted around the cordon wire during vine development, in order to prevent the arm from being strangled as it becomes thicker. Simply attach the cordon arm at its tip to the cordon wire.
In vines where short bearer arms (spurs) are getting too long, an experienced pruner should cut a water shoot in a suitable position to one bud at this stage, so that a new bearer may be developed to replace the old one in due course of time.
Compiled by: VinPro (SA) Consultation Services