Mechanical harvesting has become well-established in the Orange River region over the past decade and this has also presented the opportunity to apply mechanical pruning. The correct application of this practice is important to achieve satisfactory long-term results.
Wine grape cultivation in the Orange River region has traditionally been done using the large gable, slanting and T-trellis systems (Photo 1). Over the past decade, there has, however, been a greater emphasis on mechanical harvesting, and the high-wire hedge systems are increasingly used. The reason for this is that producers require a lot of manual labour during harvest time for the drying of raisins. In fact, there has been a major increase in raisin production in this area. The other consideration is that labour costs in the Orange River area have risen substantially. According to the latest Vinpro Cost Guide figures, labour costs in the Orange River are calculated at R25 893 per hectare compared to R13 493 for the Olifants River, which is much more mechanised. In the Olifants River, 97% of grapes are mechanically harvested, compared to 28% in the Orange River (2024/2025 Vinpro Cost Guide).
PHOTO 1. Colombar cultivated with a gable system where the long bearers have been pruned.
Mechanical pruning started to take off in South Africa in the 1990s after the trend flew over from Australia, where labour costs are astronomically high and mechanical pruning was developed in certain areas (mostly interior irrigation areas) as an affordable option. It is currently used successfully in parts of the Olifants River, Robertson and the Breedekloof. According to SAWIS statistics, the past decade has also seen the emergence of vineyards in the (mechanically-pruned) two-strand hedge category in the Orange River (Figure 1).
FIGURE 1. Surface (hectares) of the different trellis systems in the Orange River region. The total wine grape area was 4 447 ha in 2013 and 2 405 ha in 2023.
Robertson is a region that has already been applying mechanical pruning for some time, and a lot has been learned from trials under local conditions. Briaan Stipp, viticulturist at Robertson Winery, says that mechanical pruning became a consideration after the serious frost damage of 1997. The higher cordons and increased bud load, in particular, were seen as a way to limit frost damage. They had to wait until 2019 for the theory to be tested (Photo 2). The result was that the vineyards recovered to such an extent within the same year, that crop losses were negligible.
PHOTO 2. Frost damage in Robertson (2019). (Photo: Briaan Stipp.)
With the danger of spring frost damage in the Orange River posing a major problem every year, mechanical pruning can likewise play a significant role in lessening or limiting damage in this region.
There are some producers who are already successfully applying mechanical pruning in the Orange River. The requirements are strong vigour, upright growing cultivars like Chenin blanc and Colombar, sufficient irrigation water and even soils. Many parts of the Orange River meet all the requirements and mechanical pruning can work very well. An example of such a vineyard can be seen in Photo 3. It is important to remember that these blocks form many but small bunches, which make mechanical harvesting necessary.
PHOTO 3. Chenin blanc successfully cultivated with mechanical pruning in the Orange River.
An important requirement for mechanical pruning to be sustainable over the longer term is that the ‘box’ (seen from the side) should be cut at the same place every year. Older wood will thus be cut through, but new shoots are left on the inside which provide renewal (Photo 4). The latest research indicates that the incidence of trunk diseases (a major problem in the Orange River) is lower in mechanically pruned vineyards. Prof. Halleen, former senior researcher at the ARC Infruitec-Nietvoorbij, argues that the reason for this is fewer large cuts near the cordon in mechanically pruned vineyards.
PHOTO 4. Shoots inside the ‘box’ create the opportunity for renewal in the system.
Where producers are less successful and struggle with the implementation of the system, it is mostly in cases where ‘mechanical’ pruning is done by hand. Pruners, in such cases, will almost automatically start to prune spurs and not cut through the older wood to keep the ‘box’ at the same size. Over time a build-up of bearers occurs, especially in the cracks, and dead areas develop on the arms with no bearers. The result is a poor vine form and a drastic decline in yield, as can be observed in Photo 5.
PHOTO 5. The result of trying to prune ‘mechanically’ by hand.
Correcting this situation is not always easy, but without intervention the degradation due to apical dominance later becomes impossible to reverse. Photo 6 shows a vineyard where drastic cutting back has been initiated. The potential loss of yield is a concern that is addressed by braiding shoots onto the bare arms. In cases where this practice was followed, a drastic decline in yield was not observed. The method can thus be recommended to obtain the desired vine form within a few pruning seasons.
PHOTO 6. Braided-in shoots were used to close gaps on the cordon so that the high build-up of bearers could be pruned back. Henceforward the ‘box’ should be kept at the same size.
Conclusion
Due to rapid cost increases, producers in the Orange River region are under severe financial pressure. Wine grape cultivation has traditionally relied on a significant amount of manual labour which is required for long-bearer pruning methods and manual harvesting. With the arrival of mechanical harvesting, the opportunity to apply mechanical pruning has also emerged, with its benefits of limiting frost damage and trunk diseases. There are large parts in the Orange River where it can work very well, as already proved in some cases. The application of the system in its current form does, however, need improvement as discussed.
For more information, contact Hanno van Schalkwyk at hanno@vinpro.co.za.
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