Technical Yearbook 2023

Contents

VITICULTURE ............................................................. 6 Management of vine water stress through foliar treatment with microbial derivatives*.......................................................................7 Late pruning of the vine..........................................................................12 Manipulating Sauvignon blanc ripening through shoot trimming and crop reduction.................................................................15 Vineyard biodiversity – how to put it to work using cover crops......17 Winetech funds research towards improved Vitis planting material for the wine industry................................................................21 Seaweed-based biostimulants in Vitis vinifera L. wine cultivars – friend or foe?.........................................................................27 Chenin blanc – the versatile variety......................................................31 Soil compaction – the silent killer of conservation agriculture?........35 Managing for optimum root health.......................................................39 Winery wastewater for irrigation (Part 1): Irrigation application and water quality................................................44 Winery wastewater for irrigation (Part 2): Evaluation of catch crops on open land................................................47 Winery wastewater for irrigation (Part 3): Vineyard catch and cover crop responses.............................................50 Winery wastewater for irrigation (Part 4): Soil responses.................54 Winery wastewater for irrigation (Part 5): Grapevine and wine responses...............................................................58 OENOLOGY ..................................................................... 61 Effect of light exposure on bottled Sauvignon blanc wine..................62 Minerality in wine – understanding the concept and factors involved........................................................................................64 Fruit salad vs varnish – nitrogen sources and their impact on aroma production in wine....................................................66 Repurposing Sauvignon blanc fermentation gas for natural aroma enrichment......................................................................70 Wine in a can – rapid determination of a wine’s suitability for canning................................................................................................72 Micro-agglomeration and bioavailability of sterols – the revolutionary wine yeast protector: Faster yeast rehydration.....74 The significance of the H 2 S-C6 pathway for volatile thiol production..........................................................................80 RUBY™ – expressing thiols in red wine through an innovative yeast selection........................................................................82 PRACTICAL IN THE VINEYARD .......................................... 87 Underground irrigation at Alvi’s Drift...................................................88 Leafroll disease or deficiency symptom? ............................................... 91 Gen-Z interplanting project: preliminary results – Olifants River............................................................................................96 Manganese deficiencies ........................................................................... 98 The influence of climate change on the potassium, pH and total acidity of wines.......................................................................100

Collaboration to mitigate the risk of climate change.........................102 Recompaction of soil in existing vineyards – causes and upliftment methods............................................................105 Let nature work for you – employ winter weeds as cover crops......111 The effect of mountainous terrains on cold-unit accumulation .......114 PRACTICAL IN THE CELLAR . .................................................116 Filtration choices....................................................................................117 Preventing pinking during harvest......................................................118 The past, present and future of sulphur dioxide .................................120 Making a Top 10 Merlot – to cold soak or not...................................122 Bentonite and laccase – a doomed attraction.....................................124 The impact of cross-flow filtration on wine filterability ....................126 The trend of natural winemaking........................................................128 The pros and cons of pumping options for cellars.............................130 The ultrasonic sanitation of barrels.....................................................132 Barrel-to-barrel variation during red wine maturation.....................133 Maintaining barrels for longer use.......................................................134 Natural alternatives for sulphur dioxide . ............................................135 Factors that affect alcoholic fermentation ...........................................136 GENERAL ..........................................................................138 Confronting Climate change: Van Loveren shares their user experience feedback on the CCC carbon calculator ...................139 Outsmarting tomorrow.........................................................................145 Confronting Climate change: Wellington Wines shares their user experience feedback on the CCC carbon calculator ..................147 Uncertain times are a constant – be flexible and adaptable .............152 The value of healthy disagreements.....................................................154 Women add value – they have the power to create, nurture and transform...........................................................................155 Factors influencing knowledge uptake by practitioners – individual characteristics.......................................................................156 Factors influencing knowledge uptake by practitioners – characteristics of the knowledge source..............................................158 Factors influencing knowledge uptake by practitioners – characteristics of the knowledge..........................................................161 Factors influencing knowledge uptake by practitioners – the nature of the knowledge transfer channel....................................164 Confronting Climate change: Benchmark Report 2023 ...................166 Neethlingshof – a focus on knowledge development........................171 Confronting Cimate change: Villiera Wines shares their user experience feedback on the CCC carbon calculator ...........................172 Roodezandt RF – employer involvement establishes leaders..........177 La Bri – transfer of knowledge promotes positive self-esteem........178 Cellar Assistants’ Programme – information days and senior cellar assistants’ workshops add value....................................179

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TECHNICAL YEARBOOK 2023