South Africa Wine Research Projects 2026

PROJECTS 2026 RESEARCH

RESEARCH, DEVELOPMENT AND INNOVATION

www.sawine.co.za

TABLE OF CONTENTS

1 FOREWORD ___________________________________________2

2 VITICULTURE RESEARCH _________________________________3 2.1 Grapevine protection – Insects and pests __________________4 2.2 Grapevine protection – Fungi and bacteria __________________7 2.3 Soil and water ______________________________________ 11 2.4 Cultivation _________________________________________18 2.5 Terroir ____________________________________________22 2.6 Grapevine improvement _______________________________26

3 OENOLOGY RESEARCH _________________________________ 38 3.1 Wine improvement ___________________________________40

4 TECHNOLOGY TRANSFER _______________________________ 54

SOUTH AFRICA WINE RESEARCH 2026

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1 FOREWORD

The year 2026 represents a crucial phase for the South African wine industry, one characterised not merely by adaptation but by purposeful progression toward a more agile, knowledge-driven future. As environmental pressures intensify, market dynamics grow more complex, and societal expectations continue to evolve, coordinated research and innovation have become central to sustaining industry relevance and long-term growth. The primary objective of the South Africa Wine Research, Development, and Innovation (RDI) division is to strengthen the industry by funding academic research, providing specialised technical expertise, and effectively transferring knowledge. These efforts aim to enhance the industry’s capacity to respond to both immediate challenges and longer-term structural shifts. The 2026 Research Project Book reflects a diverse and increasingly advanced research portfolio. It encompasses new projects commencing in 2026, ongoing projects, and projects concluded in 2025. Key focus areas include grapevine health, climate resilience, soil health, regenerative agricultural practices, water optimisation, sustainable farming practices, de-alcoholised wines, wine authenticity, and knowledge transfer initiatives, with flagship programmes remaining a central priority. A defining strength of this portfolio lies in its practical orientation. Close collaboration among researchers, producers, industry bodies, and academic partners ensures that findings extend beyond theory and translate into actionable insights. This integration of science and practice is essential for enabling informed decision-making and unlocking value across the industry. This publication serves not only as a reflection of current efforts but also as a driver for future engagement. It is intended to support informed dialogue, encourage the adoption of innovation, and reinforce a shared vision for a competitive, resilient, and responsible South African wine sector.

Sincerely, South Africa Wine Research, Development and Innovation Team

OUR TEAM GERARD MARTIN: RDI Executive (gerard@sawine.co.za) ANEL ANDRAG: RDI Manager – Viticulture (anel@sawine.co.za)

DR ADRIAAN OELOFSE: RDI Manager – Oenology (adriaan@sawine.co.za) CHANDRÉ DAVEY: RDI Knowledge Transfer Coordinator (chandre@sawine.co.za) SHA-IESTA ANDERSON: Office Administrator (shaiesta@sawine.co.za)

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2 VITICULTURE RESEARCH

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

2.1 GRAPEVINE PROTECTION – INSECTS AND PESTS

RISK MANAGEMENT SYSTEM FOR DROSOPHILA SUZUKII TO INFORM MANAGEMENT DECISIONS AT DIFFERENT SPATIAL SCALES

SU EE PA 25-01 Prof Pia Addison, Department of Conservation Ecology and Entomology, Stellenbosch University Start date: 2025

AIM AND INDUSTRY RELEVANCE: Unlike other Drosophilidae (vinegar flies), Drosophila suzukii or Spotted Wing Drosophila (SWD) females can cause significant damage to soft-skinned fruit such as wine- and table grapes, stone fruit and soft berries like blue- and raspberries due to the ability to damage healthy and undamaged fruit by using a serrated ovipositor and lay their eggs. Due to a lack of knowledge of the risk SWD poses to the fruit industry, this project aims to develop a risk management system to assist the fruit industry in decision-making on a geographical scale. The project will generate new information on the fruit/cultivar/variety susceptibilities to SWD and determine alternate host status, distribution and phenology in production areas. GIS and Data CoOp integration will bring about regular, up-to-date risk maps after demographic changes of SWD in different fruit and cultivar types and climates are monitored.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

EXPLORING INTEGRATED PEST MANAGEMENT PRACTICES FOR DROSOPHILA SUZUKII IN SOUTH AFRICA

SU EE PA 25-02 Prof Pia Addison, Department Conservation Ecology and Entomology, Stellenbosch University Start date: 2025

AIM AND INDUSTRY RELEVANCE: Drosophila suzukii (Matsumura), the spotted wing drosophila (SWD), can damage several soft skinned fruits, including cherries, grapes, blueberries and stone fruit. They are indigenous to Asia, and unlike other vinegar flies, the female D. suzukii can lay eggs in whole and intact ripening fruit using a serrated ovipositor. Due to the short generation cycle of D. suzukii , crops are at risk close to harvest, when chemical interference may not be possible due to potential residues left behind. The project aims to use integrated pest management to explore and assess biological control as an alternative for managing D. suzukii in South Africa. • Commence and maintain a SWD colony for laboratory studies. • Development of attractants for use in SWD management. • Evaluate currently available commercial attractants in attract and kill applications for SWD in South Africa. • Assess the diversity of parasitoids within the Drosophilidae family. • Screen potential entomopathogenic- nematodes and fungicides against SWD in laboratory bioassays. The steps included to achieve the outcome are as follows:

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

ESTABLISHING A BARCODING DATABASE OF LOCAL PESTS OF DECIDUOUS FRUIT

SU-EE PA 23-01 Prof Pia Addison, Department of Conservation Ecology and Entomology, Stellenbosch University Start date: 2023

AIM AND INDUSTRY RELEVANCE: This project aims to develop new knowledge regarding South African pests and to have an ac curate, repeatable and rapid identification method for such pests to ensure market access and good management. Morphological identifications of insects can be problematic when dealing with immature stages or species complexes, such as with the banded fruit weevil complex and fruit flies ( Ceratitis rosa and Ceratitis quilicii ). Immature insects (e.g. fruit-fly larvae) must be reared first since morphological identifications can only be made with adult insects. With validated sequencing, where pest insects are identified by taxonomists and sequenced molecularly, it will be possible to establish a reference database for South African pest insects, especially those that are local and barcoding sequences are not available. South Africa is experiencing a shortage of taxonomists for various insect groups, which means there will be no experts available for morphological insect identifications in the future, as very few people are being trained to take over. Accurate insect identifications significantly impact the management of pests, specifically those of quarantine significance, since incorrect identifications lead to loss of access and financial implications for growers. The outcome of this project will allow for easier identifications by people not trained as Entomol ogists. It is critical, however, to establish a good morphological base on which to make these sequences available.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

2.2 GRAPEVINE PROTECTION – FUNGI AND BACTERIA

BREEDING WINE GRAPES RESISTANT TO POWDERY AND DOWNY MILDEW

P04000058 Ms Phyllis Burger, ARC Infruitec-Nietvoorbij, Stellenbosch Project is co-funded by the ARC Infruitec-Nietvoorbij

Start date: 2014 Flagship Project

AIM AND INDUSTRY RELEVANCE: The aim, ultimately, is to breed new, high yielding cultivars, that will produce high quality V. vinifera type wine and have tolerance to downy and/or powdery mildew and/or to Botrytis under local conditions. In this project crosses are made to develop cultivars with disease tolerance and good crop and wine making characteristics. Objectives of the project include: • Screening of seedlings obtained from crosses for tolerance to downy and powdery mildew; • Identifying potential parents with disease tolerance and suitable qualities to be used in crosses; • Making crosses, stratifying and germinating seeds; • Developing and establishing seedlings in tunnels and older plants in vineyards; • Identifying and importing cultivars with tolerance to fungal diseases, if possible.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

THE PRACTICAL IMPACT OF SEXUAL REPRODUCTION OF GRAPEVINE POWDERY MILDEW ON REDUCED FUNGICIDE SENSITIVITY

P04000325 Dr Minette Havenga, ARC Infruitec-Nietvoorbij, Stellenbosch Project is co-funded by the ARC Infruitec-Nietvoorbij Start date: 2023

AIM AND INDUSTRY RELEVANCE: This project will develop new knowledge regarding the primary inoculum, dominant reproductive strategy and basic biology of the powdery mildew fungus. Factors that will be evaluated include environmental requirements, the level of reduced sensitivity to DMI and QoI fungicides in South African vineyards and the effect of post-harvest application on chasmothecia development. Powdery mildew causes serious economic damage in all grape-growing regions. Only a few sexual structures (chasmothecia) were observed in 1996-1999 in Stellenbosch. Since 2015, high num bers of chasmothecia have been common on leaves at the later stages of the growing season in Western Cape vineyards. Sexual reproduction may lead to better-adapted individuals that are less responsive to fungicides. Due to climate change, Western Cape springs are becoming wetter. During bud break, conditions are now more favourable for releasing sexual spores. Asexual and sexual reproduction require different conditions, yet the primary inoculum for the infection is unknown. Therefore, disease models cannot effectively predict fungicide timing. Industry experts suspect reduced sensitivity to QoI and DMIs. The project aims to determine the primary inoculum source, the level of reduced sensitivity and the effect of sexual reproduction on reduced sensitivity. The project aims not to determine whether specific products have a reduced efficacy but to evaluate biological factors contributing to decreased management. The results will provide information to calibrate prediction models accurately to the environmental requirements of the dominant reproductive system, which will increase the efficacy of fungicide spray programmes and reduce overall fungicide use.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

NEW PRUNING WOUND PROTECTION STRATEGIES AGAINST TRUNK PATHOGENS IN ROOTSTOCK MOTHER VINES

P04000333 Dr Minette Havenga, ARC Infruitec-Nietvoorbij, Stellenbosch Project is co-funded by the ARC Infruitec-Nietvoorbij Start date: 2023

AIM AND INDUSTRY RELEVANCE: A previous project (P04000108) concluded that rootstock mother vine pruning wounds remained susceptible to Phaeomoniella chlamydospora infections for up to 42 days after pruning. Although several chemical, biological and chemical + biological treatments reduced P. chlamydospora inci dences in artificially inoculated Ramsey and 101-14 Mgt. pruning wounds, the study recommended that more pathogens and rootstock varieties be investigated. Fungicide mixtures will also have to be evaluated to broaden the efficacy of treatments to protect vines against the onslaught of several pathogen groups that all differ in their sensitivity towards fungicides. The use, availability and range of fungicides are under increased pressure worldwide. The search for alternative or biological control agents is crucial to securing sustainable grape production and market access. The study aims to evaluate chemical and biological control agents in various combinations to provide effective pruning wound protection against a range of grapevine trunk pathogens to pro duce high-quality propagation material. There is no published literature on the use of chemicals or biological control agents on rootstock (Vitis spp.) pruning wounds. All previous studies were done on wounds in vineyards (Vitis vinifera) and were not always tested against a wide range of grapevine trunk disease pathogens. The duration of rootstock wound susceptibility across a wide range of grapevine trunk disease pathogens is unknown in SA and worldwide. The benefit of the project to the industry will be a significant contribution towards producing high-quality grapevine propagation material that will contribute to higher take percentages in grapevine nurseries and better establishment of young vines in new vineyards.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

FORMULATION AND EVALUATION OF MICROBIAL CONSORTIA FOR BIOLOGICAL CONTROL OF GRAPEVINE FUNGAL PATHOGENS SAGWRI ES 22-01 Prof Evodia Setati, South African Grape and Wine Research Institute, Stellenbosch University Project is co-funded by the Department of Science and Innovation and the National Research Foundation Start date: 2022 AIM AND INDUSTRY RELEVANCE: The study’s main objective is to construct yeast-bacterial consortia that have antifungal activity against grey rot and mildew disease agents in grapevines and can be used as biocontrol agents. Existing biocontrol agents are mainly single species formulations which are sometimes ineffective under varying environmental conditions. Globally, there is growing interest in reducing the number of chemical fungicides used to control grapevine pathogens such as Botrytis cinerea , Plasmopara viticola and Erysiphe necator . Alternative biological formulations comprising microbial strains are commercially available for use in vineyards. However, not all of them work effectively and consistently under varying field conditions. Consequently, further research is necessary to identify new biological agents with higher efficacy. In the current study, we aim to generate multi-species microbial consortia for the biological control of bunch rot, powdery mildew and downy mildew. Existing biological control agents are based on single microbial species. We believe that multi-species consortia comprising strains with different modes of action that grow optimally under different environmental conditions will offer more efficacy in field conditions. By selecting organisms that do not negatively affect wine fermentation and are tolerant to chemical fungicides currently in use, we believe we can generate biological control agents that can complement existing fungicide spray programs and reduce chemical fungicide use.

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2. VITICULTURE RESEARCH NEW PROJECT

2.3 SOIL AND WATER

NEW SMART IRRIGATION SYSTEM FOR MONITORING AND MEASURING WATER USAGE IN WINE GRAPES

SAGWRI CP 26-01 Prof CA Poblete-Echeverria, South African Grape and Wine Research Institute, Stellenbosch University Project is co-funded by the Water Research Commission Start date: 2026

AIM AND INDUSTRY RELEVANCE: This project is co-funded with the WRC and focuses on improving water management in South African viticulture by developing a low-cost smart irrigation system. By integrating advanced ground-based sensors with artificial intelligence–driven data analytics, the system will provide accurate, real-time estimates of actual evapotranspiration (ETa), the most reliable indicator of vineyard water use. The approach addresses the limitations of existing irrigation tools and remote sensing methods by combining local, in-field measurements with intelligent modelling to deliver practical decision support tailored to vineyard conditions. The primary aim is to develop, validate, and demonstrate a low-cost and scalable smart irrigation system that enables precise, data-driven irrigation scheduling in vineyards. By accurately quantifying ETa in real time, the project seeks to improve irrigation efficiency, optimise water use, and enhance grape yield and quality, particularly for small to medium-scale producers operating under water-limited conditions. Water scarcity is a critical constraint for South African agriculture, and viticulture is especially sensitive to suboptimal irrigation. This project directly supports the wine industry’s strategic objective of improving water-use efficiency by providing a cost-effective, accessible precision irrigation tool. The outcomes will reduce water losses, improve vineyard sustainability and climate resilience, and strengthen the competitiveness of the wine sector. In addition, the project creates opportunities for digital agriculture services aligned with SA Wine’s flagship innovation initiatives, supporting broader adoption of innovative technologies across the industry.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

EVALUATION OF SOIL HEALTH INDICATORS IN THE STELLENBOSCH WINE GRAPE REGION

SU SS AH 25-01 Prof Ailsa Hardie-Pieters, Department of Soil Science, Stellenbosch University Start date: 2025

AIM AND INDUSTRY RELEVANCE: Soil health is challenging for growers to manage due to limited scientific research available on the topic, particularly in commercial vineyards in South Africa. Although numerous soil health tests are available to growers, their importance to winegrape production is unclear, and there is no benchmark for these indicators. The project goal is to assess the relevance of soil health indicators to the functions of wine grape soil health and establish benchmark values for these indicators. A modified soil health assessment framework based on soil texture will be used in commercial vineyards, focusing on the Stellenbosch region as a starting point. The results derived from this study can serve as a foundation for designing studies in other winegrape production areas to establish region-specific soil health assessment frameworks.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

WATER USE AND PERFORMANCE OF GRAPEVINE CULTIVARS IN RESPONSE TO CROP LOAD AND WATER REPLENISHMENT FROM THE SUBSOIL

SU-SS-J-MV 24-01 Mr John-Murray Visser, Department of Soil Science, Stellenbosch University Start date: 2024

AIM AND INDUSTRY RELEVANCE: Water scarcity challenges continue to be increasingly prominent, especially in wine-growing regions. One way of addressing this challenge is by growing more drought-tolerant grape cultivars. As a result, a research project has been conducted since 2018 to evaluate the drought tolerance of a series of eight white and nine red cultivars. In this follow-up study, additional matters will be addressed, which include: • A comparison of the evapotranspiration of individual cultivars • How different crop loads affect cultivar performance • How the grapevines can ripen their crops while only using a fraction of one millimetre of water per day from January onwards. In this regard, two possible water sources will be investigated, namely: – Roots that explore the subsoil for available water – Water movement from the subsoil to the root zone through diffusivity Consequently, the main goal of the proposed project will be to assess the water usage and per formance of specific drought-tolerant cultivars as affected by crop load, root distribution, and water movement from the subsoil. The results will advise producers regarding differences in cultivar water use and crop load’s wa ter-saving, quality-enhancing and financial benefits. They will also clarify the role of the subsoil as a store for winter rain.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

EVALUATION OF ORGANIC FERTILISERS ON SOIL QUALITY AND WINE GRAPE PERFORMANCE

SU-SS AH 24-01 Prof Ailsa Hardie-Pieters, Department of Soil Science, Stellenbosch University Start date: 2024

AIM AND INDUSTRY RELEVANCE: Wineries experience consumer pressure to produce wines from vineyards using organic fertilisers, which are perceived to be more sustainable and environmentally friendly. Synchronising organic- or mineral fertiliser nutrient availability with crop uptake requirement is important to ensure high nutrient use efficiency and optimum crop production. In South Africa, there is a notable scarcity of local scientific data on how organic fertilisers impact the production of wine grapes. The extent to which organic fertilisers can provide the necessary quantities of mineralised nitrogen in sync with grapevine demand is not well known. This study aims to fill this knowledge gap by comprehensively evaluating and comparing major types of organic fertilisers to conventional ones and their impact on soil quality and winegrape production. To initiate this study, a comprehensive literature study will be conducted, whereafter a field trial is planned. The field trial will occur in a commercial 12-year-old Chardonnay vineyard grafted on Ramsey on a farm in Robertson. The different applications will be manually applied over three years. Each plot’s soil chemical and physical properties will be measured and identified before the commencement of the study. During the first year of the study, controlled laboratory mineralisation will be conducted to compare the C, N & P mineralisation dynamics of locally available organic fertilisers. The different treatments are as follows: • Control (no compost or fertiliser) • Commercial granular fertiliser applied after harvest, bud burst, and fruit set based on vine vigour (max 40kg/ha) • Blood-based organic fertiliser • Pelletised chicken manure organic fertiliser • Plant- & animal waste compost When all the data have been gathered, a financial evaluation will be conducted to ensure cost/ benefit figures support the vineyard’s performance.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

A MODEL VINEYARD IN POTS TO STUDY GRAPEVINE/SCION RESPONSES TO WATER LIMITATION

FShip Water 4 Prof Melané Vivier, South African Grape and Wine Research Institute, Stellenbosch University

Start date: 2023 Flagship Project

AIM AND INDUSTRY RELEVANCE: This research will aim to generate scenarios of water limitation on grapevines that can test the impact of the timing of and the severity of the water limitation, as well as the ability of the vines to adapt to the limitation and recuperate after successive drought scenarios. This project will provide a novel resource to the SA Wine Flagship Water Programme, namely a potted vineyard comprising a robust experimental design of 29 plant combinations (grafted and ungrafted vines), repeated nine times. It extends and draws on the other FShip Water projects (Fship 1-3) and will particularly support the ongoing research and showcasing of results obtained from Water Fship 3. The potted trial includes additional scion/rootstock combinations (grafted and ungrafted) not evaluated in FShip Water 3. With the vines planted in pots, a greater level of control can be achieved, a unique feature. When the plants experience water stress and to what level the stress will develop can be controlled. Any soil and geospatial variability are removed by using pots, and the genotype responses can be monitored with fewer confounding variables. More severe stress responses in a shorter period can be generated due to the limited soil volume, and rain can be excluded by covering the pots. Furthermore, the location and layout of the trial make it ideal for sensor and technology testing. This study will yield both academic outputs and practical information suitable to be transferred to the industry. The potted vines and the planned experiments will be ideal for showcasing the impacts of the modulated water limitations. The trial will serve as a demonstration site for indus try professionals and other stakeholders and where student engagement and training can occur.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

PRODUCING QUALITY GRAPES WITH LIMITED WATER

FShip Water 3 Prof Melané Vivier, South African Grape and Wine Research Institute, Stellenbosch University Project is co-funded by the Water Research Commission

Start date: 2022 Flagship Project

AIM AND INDUSTRY RELEVANCE: This study aims to evaluate and compare the adaptability and resilience of current commercial scion/rootstock combinations established and maintained under both optimal and sub-optimal water conditions using a holistic approach and novel techniques. The study’s main hypothesis is that grapevines (scions and rootstocks in combination) display adaptation to non-lethal water limiting conditions (through intrinsic and extrinsic factors) that can lead to their resilience to water stress conditions. From a practical point of view, this project intends to answer questions like “Can commercially planted scions/rootstocks adapt to much less water and still produce quality grapes?” and “What would be the critical aspects to consider towards such a goal?”. These seem like simple questions, but they cannot be answered without recognising the complex interaction of many factors that influence a vine’s success and resilience in a specific (natural or manipulated) environment. Therefore, they are currently largely unanswered. The Water Research Programme provided a model vineyard where grapevine water stress studies can be conducted over the lifespan of grapevines on a vineyard scale. This vineyard was designed (site selection, row layout and rootstock-scion selection) by the Water Programme Committee Workgroup and established in 2020 through a partnership between VinPro, Winetech and Stellenbosch University. The model vineyard will be a long-term resource to transfer knowledge and skills to the industry and viticulture students on the topic of grape production with limited water. It can showcase the outcomes of limiting water on a seasonal basis and over many seasons on a range of scion/rootstock combinations. The impact of innovative technologies in monitoring water stress could also be showcased.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

MEASURING THE EFFECT OF COVER CROPS ON SOIL AND VINE HEALTH, AND GRAPE QUALITY

EXPCo G32-22 Ms G Carlse, Experico, Stellenbosch Start date: 2023

AIM AND INDUSTRY RELEVANCE: This project aims to build on existing knowledge and investigate the effect of cover crop mixes on soil health and grapevines. With increased interest in more sustainable farming practices, more research is being done on using cover crops in agricultural systems. Local cover crop trials have recently been conducted in vineyards, focusing on cover crop mixes and their success, cover crop biomass and weed suppression. Using the right cover crop mix can increase soil moisture, improve soil structure, suppress weeds and pests, increase plant-available nutrients and improve crop resilience. This, in turn, reduces irrigation, pesticide, and fertiliser costs. In this project, the viability of growing cover crops under the vine and growing permanent cover crops will also be investigated. Analysis of nematode communities will add to the knowledge base of nematode host status of cover crop species. Care will be taken to include cover crops that will have a suppressive effect on inoculum and infestation levels of pathogens and/or pests. This project aims to provide the industry with crucial information to fill the knowledge gaps about selecting cover crops to improve the properties and ecology of soil in vineyards.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

2.4 CULTIVATION ReGenWine (ReGEN)

SAGWRI MAV 25-01 Mrs Julia Harper, Faculty of AgriSciences, Stellenbosch University Start date: 2025

AIM AND INDUSTRY RELEVANCE: Producers should consider diversification strategies to address climate change, rising production costs, and the increasing demand for sustainably produced wine. ReGEN advocates for a shift to regenerative practices to address these challenges. However, wine farmers require scientific validation that regenerative farming systems can sustain wine quality and production long-term and that the benefits justify the investment costs involved. The project aims to address the viability of transitioning from conventional farming practices to a more regenerative approach, while also quantifying the long-term benefits to the soil, plants (cover crop and vine) and quality of wine. A pre-trial with a multidisciplinary project team will be conducted on a commercial farm to evaluate the benefits of regenerative practices for the soil, plants, animals and wine production. This will allow for a thorough evaluation of regenerative agricultural practices over time. The project will assess the following based on the key principles of regenerative agriculture: • Evaluate the impact of adopting the five principles of regenerative practices on soil health, soil microbiome, vine development, grape and wine quality, and compare the economic sustainability of these practices to conventional farming. • Develop a better comprehension of how regenerative agriculture can support the creation of a circular economy within vineyards. • Distinguish emerging regenerative practices that can be tested and potentially be applied by the wine industry.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

ANALYSING INDUCED DIVERSITY IN A COLLECTION OF PINOTAGE PLANTS AFTER GAMMA IRRADIANCE P04000060-2024 Prof Melané Vivier, South African Grape and Wine Research Institute, Stellenbosch University and Ms Phyllis Burger, ARC Infruitec-Nietvoorbij, Stellenbosch Project is co-funded by the ARC-Infruitec-Nievoorbij Start date: 2024 AIM AND INDUSTRY RELEVANCE: Pinotage has only a few commercially available clones similar in viticultural and oenological properties. This project builds on the previous work done in 2017 and 2018 (optimised methodology to establish a gamma-irradiated Pinotage collection) and from 2019 until 2023 (irradiated Pinotage collection initially characterised). This project aims to expand upon these prior research efforts and perform viticultural and oenological assessments on selected groups of vines. This aims to pinpoint promising candidates for the clonal selection of Pinotage. The objectives for this project are as follows: • Develop a data management plan for the project. • Maintain and extend the field site where an irradiated population of Pinotage plants are kept. • Investigate the effects of gamma irradiance on the cluster, canopy, and wine quality traits of three Pinotage clones in a field trial site. • Select promising individuals for grafting to rootstocks for further analyses.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

IN-FIELD QUANTIFICATION OF GRAPEVINE KEY ANALYTES USING PORTABLE INFRARED SPECTROSCOPY DEVICES

SAGWRI JT 24-01 Dr Jose Luis Aleixandre-Tudo, South African Grape and Wine Research Institute, Stellenbosch University Start date: 2024

AIM AND INDUSTRY RELEVANCE: Knowledge of key analyte levels in the grapevine growing season is hindered by analytical limitations such as time-consuming protocols, expensive analytical procedures, and limitations of the technology for direct measurement in grapevine tissue. Furthermore, spectroscopy calibrations are not optimised for in-field conditions. This project aims to supply optimised prediction calibrations for in-field direct quantification of important analytes from grapevine organs, such as shoots, leaves and berries. The target analytes are carbohydrates, nitrogen and amino acids. Ambient variability will also be incorporated into the models to optimise prediction accuracies. The Chenin blanc vineyard, which is part of the research project “Premium and profitable Chenin blanc wines,” and the Flagship Project 3 vineyard will be the sources used to acquire the required variability for calibration optimisation. Three different experiments will be conducted under this objective. • The Flagship Project 3 vineyard’s nutrient content will be monitored and assessed during a growing season using optimised calibrations. • Amino acid development will be monitored in the Chenin blanc experimental vineyard during grape ripening. • Lastly, the effect of the nutrient content on the take percentage of grafting material will be assessed. In this instance, a sample set containing materials with varying nutrient content levels will be utilised to demonstrate the concept. If successful, the project’s outcome will benefit the nursery industry’s supply chain due to the potential optimisation of plant material. Overall, it will improve the quality of the plant material, grapevine development and grape and wine quality.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

THE MAINTENANCE AND EXPANSION OF A GENETIC SOURCE FOR VINES

P04000068 Ms Phyllis Burger, ARC Infruitec-Nietvoorbij, Stellenbosch Project is co-funded by the ARC Infruitec-Nietvoorbij Ongoing

AIM AND INDUSTRY RELEVANCE: This project is responsible for the maintenance and expansion of the South African national grape genebank. It involves: • Maintaining field genebanks and a backup repository; • Importing of promising cultivars for wine making and breeding purposes; • Adding newly imported accessions and new locally bred accessions to the genebank; • Supplying plant material to local Plant Improvement Organisations and to institutions abroad on request; • Propagating backup plants of accessions that are dying in field genebanks; • Ampelographical description of cultivars for authentication; • DNA fingerprinting of accessions in the genebank; • Viticultural and oenological evaluation of promising wine grape cultivars.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

2.5 TERROIR

ESTABLISHMENT OF THE TECHNICAL AND SCIENTIFIC BASES FOR AI APPLICATIONS IN WINE PRODUCTION: STUDY CASE ON VITICULTURE, YIELD AND PHENOLOGY AI MODELS SAGWRI CP 25-01 Prof Carlos Poblete-Echeverria, South African Grape and Wine Research Institute, Stellenbosch University Start date: 2025 AIM AND INDUSTRY RELEVANCE: Human field scouting has long been used to monitor various vineyard processes and practices. However, this approach is expensive, labour-intensive, subjective and often lacks precision. New methods to assess vine performance that move beyond traditional practices are needed. Artificial intelligence (AI) offers a groundbreaking and powerful technological tool to enhance and improve present monitoring methodologies and data management processes. Designing AI algorithms with fast and proficient learning tempo, quick convergence to solutions, effective abstraction skills and ease of implementation are essential to developing a successful and effective AI model. The project aims to lay the technical and scientific groundwork for implementing AI applications in the South African wine industry by building both human and technological capabilities necessary for these models. A case study on yield and phenology will be the focus point for establishing the core principles. In addition, these principles can be applied to other AI applications in both Viticulture and Oenology.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

GENERATING HIGH RESOLUTION, VINE-SPECIFIC ACTUAL EVAPOTRANSPIRATION MAPS AT DAILY INTERVALS

SU-GEO TS 24-01 Dr Tara Southey, Department of Geography & Environmental Studies, Stellenbosch University Start date: 2024

AIM AND INDUSTRY RELEVANCE: Due to population and economic growth, climate change and the decline in water quality, South Africa faces water scarcity challenges. Accurate estimates of crop water demand through evapotranspiration (ET) modelling are increasingly important to improve irrigation management and maximise water use efficiency. This study aims to develop and demonstrate a methodology for generating high-resolution (10 m), daily, grapevine-specific, actual ET maps. The project has a six-phase work plan approach. 1. Review methods, algorithms and data sources for calculating actual ET (Eta). 2. Hourly Et0 values will be calculated for each weather station point. 3. Images from Sentinel-2 will be sourced and compared to existing crop coefficient (Kc) values using regression analysis. 4. The best-performing vegetation index-based Kc model from Workplan 3 will be combined with the Et0 surfaces from Workplan 2. 5. Inter-row areas with established cover crops (or dense weed populations) can significantly affect the growth and vigour signals received from the satellite. An attempt will be made to quantify this effect by comparing indices derived from 10 m resolution images to those derived from 50 cm resolution images. 6. Using in-field observations by an expert panel, the Eta surfaces from Workplan 4 will be evaluated at key grapevine growth stages and in response to irrigation and/or rainfall events. The project’s final phase involves engaging with industry role players to investigate the potential of integrating the developed method with existing irrigation scheduling tools and determine the appetite for offering ET0 and ETa maps through TerraClim.

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2. VITICULTURE RESEARCH FINAL REPORT

CLIMATE DATABASE AND TERRACLIM TOOL DEVELOPMENT

FShip TerraClim 2022 Dr Tara Southey, Department of Geography & Environmental Studies, Stellenbosch University Project is co-funded by the Department of Science and Innovation

Start date: 2022 Flagship Project

AIM AND INDUSTRY RELEVANCE: This project continues to build on the Terraclim project that started in 2019. The initial TerraClim project has provided an excellent foundation for research. The online Terraclim platform (www.terraclim.co.za) is a new, integrated technology tailored to the agriculture sector. It is ideal for aiding long and short-term decision-making at the farm and field level in the context of climate change in the complex terrain of the Western Cape. Terraclim provides high-resolution terrain and temperature information based on a robust climate and terrain database. The project will maintain, extend and improve the climate database and wireless logger networks. However, the initial TerraClim project also generated a wealth of data that has not yet been exploited. This new project aims to mine the geospatial database (geodatabase) for information related to climate variability and cultivar suitability. This research aims to answer the ultimate question of what actions are required to ensure a sustainable future for the wine industry. However, to answer this question, we first need to improve our understanding of climatic variations of the recent past so that we can identify trends and make predictions of how variations may play out in the near- and long-term future. With this background, we can potentially improve our understanding of how climate change may affect the wine industry, especially within the context of what has happened in the wine industry over the past few years. The continuation of the Terraclim project builds on the previous aim to improve our understanding of how the climate in the Western Cape is changing and how the grapevine/plant is responding to these changes. This knowledge is critical for the sustainable future of wine production in South Africa. This project will ultimately: 1) provide up-to-date climate situational reports for within-season decision-making 2) delineate areas most at risk of climate variability to inform new plantings 3) map terroir to understand wine character better 4) identify areas most suitable for the planting of specific cultivars 5) maintain and expand the centralised climate database.

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2. VITICULTURE RESEARCH COMPLETED PROJECT

ASSESSING THE DROUGHT TOLERANCE OF SELECTED GRAPEVINE SCION CULTIVARS UNDER DRYLAND CONDITIONS IN THE SWARTLAND REGION

P04000207 Dr Carolyn Howell, ARC Infruitec-Nietvoorbij, Stellenbosch Project is co-funded by the ARC Infruitec-Nietvoorbij Project completed: 2025

AIM AND INDUSTRY RELEVANCE: To ensure the sustainability of South African viticulture amidst increasing water scarcity, this study evaluated the performance of alternative drought-tolerant scions under dryland conditions. This research, which began in 2018, monitored soil and grapevine water status. The researchers identified significant differences in vegetative growth, yield and wine characteristics between eight white and nine red cultivars grown under dryland conditions, confirming that specific varieties can maintain high yields without sacrificing wine quality. Grenache noir, Macabeo, and Piquepoul blanc emerged as high-yield leaders, while cultivars such as Arinarnoa, Durif, Grenache noir, Marselan, and Pinotage demonstrated superior overall yield and quality. Chenin blanc, Macabeo, Marsanne, Piquepoul blanc and Vermentino showed moderate performance compared to the other white cultivars. Ultimately, the adoption of these climate-resilient scions offers the industry a strategic path to long-term viability and a unique competitive advantage in the global market.

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2. VITICULTURE RESEARCH NEW PROJECT

2.6 GRAPEVINE IMPROVEMENT ESTABLISHMENT OF A WIDE PANEL OF GLRAV-3 VARIANTS FOR EVALUATIONS OF RESISTANCE/DETECTION

PATHSOL GP 26-01 Prof Gerhard Pietersen, Patho Solutions Start date: 2026

AIM AND INDUSTRY RELEVANCE: This project addresses the need for durable resistance to grapevine leafroll-associated virus type 3 (GLRaV-3) by identifying and establishing a representative panel of GLRaV-3 strains present in South Africa. Current resistance screening relies on a limited number of pure virus sources that do not reflect the full local diversity of the virus. By characterising and maintaining pure sources of locally relevant GLRaV-3 variants, the project will support more accurate evaluation of grapevine resistance and improve the reliability of virus detection methods. The project aims to assess the resistance of the GLRaV-3 strain through graft inoculation with five pure sources of GLRaV-3 strains representative of those occurring in South Africa, and to use these to assess the durability of resistance in selected grapevine rootstock clones, such as Ramsey. This will ensure that resistance is effective against a wide range of virus variants before resistant material is released to industry. GLRaV-3 is a significant constraint on grapevine productivity and wine quality. Developing grapevine rootstocks with durable, broad-spectrum resistance will significantly reduce long-term disease risk and management costs for growers. The project will provide the industry with more reliable, disease-resistant planting material and strengthen virus detection, thereby supporting vineyard sustainability and biosecurity.

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2. VITICULTURE RESEARCH NEW PROJECT

EVALUATING THE ADOPTION AND EFFICACY OF GRAPEVINE LEAFROLL DISEASE CONTROL IN THE SOUTH AFRICAN WINE INDUSTRY

PATHSOL HR 26-01 Mr Herman Rossouw, Patho Solutions Start date: 2026

AIM AND INDUSTRY RELEVANCE: Grapevine leafroll disease (GLD) remains a significant constraint to productivity and wine quality in South Africa, causing substantial economic losses despite long-term investment in control measures. This project will evaluate the adoption, implementation, and effectiveness of current GLD control practices across the wine industry. Using industry surveys supported by field inspections, the study will assess how control strategies are applied in practice and model the economic benefits derived from damage offset by these measures. The primary aim is to generate evidence-based insights into the effectiveness and economic value of existing GLD control strategies. The project seeks to quantify the extent to which current practices reduce yield and quality losses, estimate the financial benefits, and identify gaps or inefficiencies in disease management to inform improved decision-making. GLD can reduce vineyard productivity by an estimated 30–50%, posing a serious threat to vineyard longevity, profitability, and sustainability. By providing the first comprehensive evaluation of GLD control efforts in South Africa, this project will support more efficient allocation of resources, refinement of disease management strategies, and improved return on investment for producers. The outcomes will contribute to enhanced vineyard sustainability, strengthened economic resilience, and the continued competitiveness of the South African wine industry in global markets.

This project has five objectives: • Select participant producers.

• Survey participants regarding GLD control practices. • Correlate GLD control measures with infection levels. • Model the economics of GLD control. • Compile findings. The project has received support and positive feedback from industry organisations and wineries.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

SELECTION OF GLRaV-3 RESISTANT ROOTSTOCKS FOR THE SOUTH AFRICAN WINE INDUSTRY

PATHSOL GP 24-01 Prof Gerhard Pietersen, Patho Solutions Start date: 2024

AIM AND INDUSTRY RELEVANCE: Grapevine Leafroll-associated Virus 3 (GLRaV-3) can be transmitted to vines during the grafting process via GLRaV-3-contaminated rootstocks. It has been demonstrated that GLRaV-3 susceptible and resistant individuals exist within the Vitis rootstock selection most frequently used in South Africa. This study aims to select GLRaV-3-resistant rootstocks of the six most vital rootstock cultivars, establish them, verify their resistance, and make them widely available to the industry. The process will start with identifying sources of potentially resistant rootstocks and then selecting GLRaV-3-resistant individuals of rootstocks 101-14 Mgt, Paulsen 1103, Richter 99, Richter 110, Ruggeri 140 and US 8-7. Additional testing will ensure no other pathogens are found in these individuals, followed by establishing resistant rootstock sources in a vector-free environment. Further confirmation of the absence of GLRaV-3 will be done, followed by GLRaV-3 resistance confirmation via artificial inoculation, in which pure sources of GLRaV-3 variants will be grafted onto young plantlets from each source of the selected rootstock. The last step will be distributing the selected immune phenotype material to plant improvement organisations within the South African wine industry.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

ESTABLISHMENT OF GRAPEVINE LEAFROLL-ASSOCIATED VIRUS 1 AND 2 ELISAS

PATHSOL GP 24-02 Prof Gerhard Pietersen, Patho Solutions Project is co-funded by Patho Solutions Start date: 2024

AIM AND INDUSTRY RELEVANCE: Grapevine Leafroll-associated Virus-3 (GLRaV-3) is the most widespread and the focus of control of leafroll-associated viruses. Other associated viruses like GLRaV-1 and -2 also occur; however, only GLRaV-3 ELISA tests are available, so there is a need for ELISAs for GLRaV-1 and -2. The Vine Improvement Association (VIA) certification scheme mandates GLRaV-1, -2, and -3 tests. In the past, this was done via a locally prepared single ELISA system that could detect these three viruses. This test, however, is no longer available, and currently, only GLRaV-3 testing is locally available and affordable. This project aims to develop ELISA tests to detect GLRaV-1 and GLRaV-2 and, if successful, combine them into a GLRaV1, -2, & -3 cocktail ELISA, which can detect all three viruses within a single test.

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2. VITICULTURE RESEARCH PROJECT IN PROGRESS

GENOMIC COMPARISON OF RAMSEY GLRaV-3 IMMUNE AND SUSCEPTIBLE SOURCES

PATHSOL GP 24-03 Prof Gerhard Pietersen, Patho Solutions and Dr Justin Lashbrooke, Department of Genetics, Stellenbosch University Project is co-funded by SF & VR du Toit Studiefonds Trust Start date: 2024

AIM AND INDUSTRY RELEVANCE: Recent, ongoing research has revealed GLRaV-3 susceptible, tolerant and immune phenotypes in Ramsey ( Vitis champinii ) sources. The reason for these differences is unknown. This project aims to compare the genomes of the different phenotypes on a molecular level in an attempt to find the underlying cause. A detailed genetic and genomic comparison between resistant and susceptible near-isogenic Ramsey individuals may lead to identifying the potential gene(s) underlying the resistance. This knowledge creates the possibility of incorporating leafroll resistance into not only other rootstocks but also into scions and to understand the virus’s mode of infection better. Vitis champinii is also a recognised stress-tolerant Vitis species, and the characterisation of its genome will also be of value in endeavours to identify further drought-tolerant vines. The project has five objectives: • Identify near-isogenic Ramsey material that shows a range of resistance to leafroll – susceptible, tolerant and immune. • Perform phased diploid genome sequencing on immune and susceptible material. • Assemble diploid genomes of the immune and susceptible clones. • Perform transcriptome analysis on immune and susceptible clones. • Screen assembled genome data and transcriptome data for functional sequence variations potentially underlying the resistance/susceptibility trait. The project has received support and positive feedback from industry organisations and wineries, highlighting the importance of finding solutions to combat the leafroll virus in the wine industry.

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