WINETECH Technical Yearbook 2020

CONTENTS

1. VITICULTURE _______________________ 6 Grapevine rupestris stem pitting- associated virus ________________________ 7 With a pinch of salt …__________________ 10 Poor detection of grapevine leafroll- associated virus type 3 in rootstocks _____ 12 Responding to climate change __________ 16 Climate change in the viticulture sectors: Overview of long-term climate trends in the Western Cape (Part 1) ____________ 18 Using thermal satellite land surface temperature to supplement weather station temperatures in the Western Cape (Part 2) __________________________ 22 Seasonal weather variation within local mesoclimates explained using high resolution climate data (Part 3) __________ 25 Impact of local site and inter-seasonal weather variability on grapevine responses (Part 4)______________________ 30 The integration of multiple view points for adaptation/mitigation strategies in the context of warmer and drier future (Part 5) _______________________________ 34

Ring nematode in grapevine – a major problem for producers and researchers_ __ 38 Katydid ecology in vineyards_____________ 41 Feedback from the 11th International Workshop on Grapevine Trunk Diseases_ _____________________________ 44 Incidence and spread of aster yellows_____ 49 Indigenous leafhopper transmits aster yellows___________________________ 52 Grape flavan-3-ol evolution under altered light and temperature conditions in Cabernet Sauvignon (Part 1)_____________ 54 Grape flavan-3-ol composition under altered light and temperature conditions in Cabernet Sauvignon (Part 2)_____________ 60 Grape flavan-3-ol and anthocyanin composition under altered light and temperature conditions in Cabernet Sauvignon (Part 3)______________________ 65 Grape flavan-3-ol evolution (Part 4): Effect of sequential harvesting on the sensory properties of the wines_ _________ 70 Eutypa-like fungi associated with grapevine cankers and dieback_ _________ 74

WINETECH TECHNICAL YEARBOOK 2020 2