WINETECH Technical Yearbook 2020

FIGURE 2. Hourly maps transitioned into an index map for hours observed between 30-35°C from November to February. The map highlights darker areas where earlier flowering and harvest can be expected compared to lighter areas.

logical stage to climatic conditions and had a strong correlation with harvest date, with an excellent correlation in more “normal” seasons. Flowering date as days after budburst could potentially be used to predict harvest date for Cabernet Sauvignon over sites within an accuracy of a few days. Similar seasonal temperature variations were observed in a case study

the coming season. Frequency analysis highlighted more observed hours between 30-35°C and 35-40°C in summer months, which resulted in earlier flowering (calcu- lated as days after 1 September) in the following season. Flowering: Flowering tended to “set the pace” for phenology in the seasons. Flowering was the most sensitive pheno-

FIGURE 1. Study sites selected (areas encircled with red) over a climate band from the cooler Elgin area to the warmer Vredendal area.

WINETECH TECHNICAL YEARBOOK 2020 31