Cutting with care, Pruning of old vines: Part three of five of a serialized report on old vines in South Africa

By Petri de Beer

South African vineyards have undergone significant transformation over the past few decades, with increased attention given to vine longevity and health rather than solely maximizing short-term yields. Among the most critical factors contributing to the extended lifespan of vineyards is the adoption of improved pruning techniques, which aim to minimize pruning wounds, optimize vascular flow, and reduce susceptibility to fungal infections, one of the primary threats to vine health and sustainability.

One of the primary drivers of vineyard decay and premature death is viral and bacterial infections. Many South African vineyards have experienced losses due to pathogen invasions, leading to the deterioration of vines well before reaching old age. Understanding how disease spreads and implementing preventive measures can significantly impact vineyard sustainability.

Historically, vineyard pruning in South Africa was primarily driven by cellar requirements, focusing on whether vines could ripen sufficient grape tonnage to meet production needs. The longevity of vines and their ability to thrive beyond a set production cycle were largely overlooked. As a result, pruning decisions were based on yield optimization rather than vine health, leading to widespread adoption of methods such as spur pruning, which guaranteed a consistent production of fertile buds.

While spur pruning effectively maintains uniform yields, it comes with significant long-term challenges, primarily an increased risk of disease and structural stress on vines. Over time, repetitive cuts made to older spurs create larger wounds, disrupting the vine's vascular system and increasing exposure to fungal pathogens. This practice, while successful in maintaining grape production in the short term, inadvertently leads to trunk diseases, limiting the productive lifespan of vineyards.

Spur pruning operates under the premise that selecting the correct bud positioning and cutting old spurs ensures proper vascular connectivity. However, as vines age, the wound surface increases, allowing for greater fungal penetration. This results in diseases such as Eutypa, which are linked to fungi that invade exposed wood surfaces, gradually causing vine decline and death.

Vineyards suffering from trunk diseases such as Eutypa show a significantly reduced lifespan, often requiring replanting sooner than anticipated. The average productive age of spur-pruned vines tends to be limited to 20–25 years, whereas properly maintained vines, following minimized wound pruning techniques, can remain productive for 50 years or more.

As discussed in the previous section of this series the maintenance of older vines is an even more pronounced problem in Europe and it is here that the first techniques for pruning specifically older vines were developed. Italian viticulturists Marco Simonit and Pierpaolo Sirch developed an approach to vine pruning, one that prioritizes vine structure, disease prevention, and longevity over short-term yield optimization. Their method is based on minimizing pruning wounds, preserving crown buds, and forming protective crown rings around cut areas to prevent dieback.

By maintaining natural sap flow and reducing instances of large wounds, this method ensures vines remain structurally intact, avoiding premature decay. Unlike spur pruning, which continuously cuts away old wood, this approach allows vines to gradually age while maintaining their productivity. The effect of these practices can be seen in the illustrations below with illustration 1a showing the effect of deadwood build up associated with traditional spur pruning in contrast to the effect of minimum wound pruning on deadwood in illustration 1b.

Illustration 1a) Dead and diseased wood caused by infections and wood die back in Cabernet Sauvignon pruned in the traditional spur method.

Illustration 1b) Cross section showing healthy wood and no infections in Cabernet Sauvignon pruned using wound minimization techniques.  Simonet, M. and Sirch, P. (2018) Simonit & Sirch, the pioneers of pruning for the well-being of the Vine Plant, vilaviniteca. Available at: https://www.vilaviniteca.es/en/blog/simonit-sirch-the-pioneers-of-pruning-for-the-well-being-of-the-vine-plant/ (Accessed: 20 May 2025).

While this method has proven effective in European vineyards, its application in South African viticulture requires modifications to suit local conditions. One of the notable challenges comes from South African vines' high vegetative growth, which can lead to excessive old spur development. In regions where vineyards experience rapid foliage expansion, controlling spur positioning and balancing vascular flow requires careful pruning adjustments.

Additionally, South African vineyards display diverse environmental conditions, from the cooler coastal regions to the hotter inland valleys, meaning that uniform pruning approaches are not always feasible. Some vineyards may still require selective adaptation of spur pruning techniques to suit high-yield environments while incorporating minimal pruning wounds where applicable.

One of the pioneers in adapting these philosophical principles to South African conditions is Rosa Kruger, a leading advocate for preserving old vines. Through her work in identifying and maintaining older vineyards, she has emphasized the importance of balancing pruning wounds with old wood retention to ensure vines remain productive for decades rather than succumbing to disease after a short lifespan.

Kruger's approach considers the unique vegetative behaviours observed in South African vineyards, acknowledging that eliminating large wounds may not always be practical. Instead, a strategic balance between traditional spur pruning and crown preservation techniques ensures that vascular flow remains intact, reducing the risk of grapevine trunk diseases, while still allowing proper bud selection to maintain yield expectations.

This South African adapted approach has been implemented through the Old Vine Project on identified old vines successfully with the aims of preserving strong wood, avoiding big pruning wounds, not cutting into olds wood and using the strongest upright shoots from vine.

The shift toward vine longevity-focused pruning is not merely theoretical, it is backed by international research and quantifiable improvements in vineyard performance. Studies  by Richard Danko assessing the impact of these pruning methods have documented:

A 60% decrease in stunted and wild shoots due to improved sap flow

A fourfold increase in sprouted buds, contributing to greater fruit-bearing potential

A doubling of cane weight, reflecting healthier vine structure

A 25% increase in grape production from vineyards utilizing minimal pruning wound techniques

These findings underscore the positive effects of strategic pruning on vineyard health, supporting the idea that vine longevity can be actively controlled through proper pruning interventions.

Notably, vineyard analysis has revealed that most old vine survivors currently in South Africa especially those above fifty years that did not have the advantage of having these new techniques applied to them are in remote areas, away from high-density vineyard zones where disease spreads more rapidly. Additionally, these older vines often underwent minimal pruning, further confirming the theories supporting low-wound pruning techniques as a key factor in vine longevity.

As South African viticulture continues to advance, pruning techniques will play an increasingly pivotal role in shaping the industry's long-term sustainability. Achieving an optimal balance between yield, disease prevention, and structural integrity necessitates a holistic approach, one that is adaptable not only to changing environmental conditions but also to the vine’s natural aging process. Effective pruning methodologies must evolve in response to both climatic variations and the vine’s developmental stages, ensuring that pruning strategies are continuously refined to support vine health, maximize productivity, and extend longevity throughout its lifetime.