Winetech Technical Yearbook 2022

AUTHORS ...................................................................................... 3 FOREWORD . .............................................................................. 4 VITICULTURE . ......................................................................... 6 Petri disease – when and how do Western Cape vineyards get infected?. ............................................................................................. 7 Smokin’ hot Western Cape terroir (Part 1)................................................ 9 Smokin’ hot Western Cape terroir (Part 2).............................................. 12 Impact of grapevine leafroll disease on grape and wine composition...... 14 Optimisation of grapevine leafroll detection by sentinel canes................ 18 Hot water treatment – effective eradication of root-knot nematodes? . ... 23 Hyperspectral – the answer to water stress? (Part 1).............................. 24 Hyperspectral – the answer to water stress? (Part 2).............................. 27 The CRISPR revolution and grapevine. .................................................. 29 Transmission dynamics of grapevine leafroll-associated virus 3 (GLRaV-3) variants ................................................................................. 32 High altitude vineyards........................................................................... 35 The bud (erinose) mite – identity crisis. ................................................. 38 OENOLOGY ............................................................................... 40 Cooling Sauvignon blanc grapes before processing – is it worth the effort, time and energy? .................................................... 41 The effect of aeration on spontaneous Chardonnay fermentations .......... 43 Elemental sulphur residues at harvest – boosting both the good and the bad. ....................................................... 44 Factors affecting sparging efficiency (Part 1) . ......................................... 46 Factors affecting sparging efficiency (Part 2) . ......................................... 48 Why does my wine smell like mushrooms?. ........................................... 50 Cork or crown closures during bottle fermentation of MCC?.................. 52 Steering away from flat and flabby Merlot . ............................................. 54 Effect of cork or crown cap closures on MCC bubbles . ........................... 57 Yeasts, smoke taint and Chenin blanc wines . .......................................... 59 The role of thiamine in sluggish fermentations and crushed dreams. ..... 62 Adding freshness back to wine with Level 2 Laktia™............................... 64

Reducing bentonite usage with a novel method to obtain heat-stable wines . ................................................................................... 68 Lipids in white winemaking – the too oft-ignored essential nutrients . ... 71 PRACTICAL IN THE VINEYARD . ......................... 74 Soil preparation – think before you do.................................................... 75 uniWines Vineyards’ quality strategy for higher-yielding vineyards ....... 79 Gen-Z – 2021 cover crop demos ............................................................. 82 Let your terroir guide your farm planning............................................... 89 Mulching on berms................................................................................. 91 Sawing back of grapevines for retraining. ............................................... 94 The cold facts about managing vineyard frost......................................... 96 PRACTICAL IN THE CELLAR .................................. 98 Effective microbiological monitoring in wine cellars ............................... 99 The use of dried yeast without rehydration........................................... 100 The making of wines with low or no alcohol......................................... 101 The benefits of aeration during fermentation ........................................ 102 Winetech vine and wine innovation watch: The use of fumaric acid to control malolactic fermentation................... 105 Actions in cork factories to prevent TCA in closures............................. 107 Calcium tartrate instability of wine. ...................................................... 108 Winetech vine and wine innovation watch: Treatment of grapes, musts and wine with pulsed electric fields . ......... 109 The complexities of sulphur dioxide...................................................... 111 Carbonic maceration............................................................................. 113 Modern amphorae and oak barrels. ...................................................... 114 Free sulphur dioxide management in barrels........................................ 115 Hot vineyards not that “VA VA” Voom after all...................................... 116 GENERAL ................................................................................. 118 Confronting Climate Change: Carbon emissions and the future of South African agriculture.............. 119 Carbon jargon – your quick guide to carbon literacy. ........................... 121 Confronting Cimage Change: Benchmark Report 2022........................ 122

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WINETECH TECHNICAL YEARBOOK 2022