“The Stellenbosch region is expecting excellent wines with good quality from a bigger wine grape harvest,” says Etienne Terblanche, Vinpro’s viticulturist for the Stellenbosch and Cape South Coast regions.
The moderate growth season as well as the seasonal rainfall at the start of the 2020 harvest, laid the foundation for a good season. The early cultivars are showing good acidity and sugar levels, whereas the later cultivars delivered wines with good concentrations, structure and desired alcohol levels.
“Stellenbosch producers can celebrate and be proud of the 2020 harvest with regards to both the crop size and quality in the cellar, despite obvious challenges and pressures because of the COVID-19 pandemic,” says Etienne.
Producers in the Stellenbosch region had a significant improvement in their productions, as opposed to the relatively small harvest in 2019. The bigger yields are mainly ascribed to a favourable, wet post- harvest period, sufficient winter cold and a moderate growth season.
The good winter cold was particularly favourable for sensitive cultivars such as Chardonnay and Shiraz, having had a positive impact with regards to budding percentages which led to a bigger harvest. Cultivars which would normally be harvested in die middle of the season, had good flowering and berry set conditions in particular. Merlot especially produced high yields, whereas Sauvignon Blanc and Chenin Blanc delivered average yields. Late cultivars such as Cabernet Sauvignon showed a conservative improvement with regards to yields, although berry dehydration occurred specifically in this cultivar, which might have a negative impact on the yields.
CLIMATE AND VITICULTURAL TRENDS
Good rainfall during the harvest and post-harvest season replenished soil profiles during this crucial time of reserve accumulation. Post-harvest irrigation was not necessary in some cases. The overall leaf fall was significantly later than in the preceding dry year. However, certain vineyards were not able to effectively accumulate reserves due to fungal diseases as a result of the moist weather conditions and this resulted in premature leaf fall. Environmental conditions as well as autumn temperatures were of such a nature that no significant regrowth took place that could subsequently limit the reserves. Early dormancy temperatures were significantly lower than in the previous season.
The winter rainfall was lower compared to the 2019 season, but still higher than during the drought of 2016 to 2018. The rainfall was average during most of the winter months, apart from a particularly low rainfall during August. Cold units started accumulating about six weeks earlier than in the previous year and it was particularly distinctive in the way in which the cold units virtually accumulated uninterruptedly until early in August this year – as opposed to the typical warm periods that were recorded during the winter time over the past few years and resulted in various challenges. However, the temperatures gradually increased during August and some of the early cultivars had bud burst up to two weeks prior to the average budding dates.
An exceptionally warm and dry spring resulted in good, even bud burst of early and mid-seasonal cultivars, after sufficient winter cold. The soil temperatures are usually low in cooler and wet spring conditions, which could result in delayed and uneven growth. However, this wasn’t the case this year. Cultivars such as Chardonnay and Shiraz initially showed excellent and even growth, mainly due to good spring temperatures and improved root activity.
The temperatures during the flowering and berry set period were average, with significantly less fluctuations than in the previous season. Good rainfall measured at around 100 mm and even more towards the end of October was crucial to replenish the dry soil profiles and to lay the foundation for good and stress-free flowering and berry set conditions. Early and mid-cultivars exceeded expectations with regards to berry set as a result of these conditions, whereas late cultivars such as Cabernet Sauvignon had to develop berry set in cooler conditions, which in turn resulted in normal berry set.
The growth season was characterised by sustained, moderate to cool day temperatures, combined with significant wind. Cool, windy conditions prevailed from November to December, with the exception of a short, warm period early in December which led to sunburn damage on susceptible cultivars. These cool conditions during the cell enlargement and division phase of the berries possibly led to smaller berry sizes, despite relatively low water stress. The region experienced gale-force winds above 90 km/h which caused damage particularly to thin canopies and some bunches. The vineyards in the mountain region were affected the most.
The 2020 harvest period was characterised by typical dry conditions and moderate temperatures. Carry-over effects from the heat during spring and effective canopies promoted ripening in the early cultivars and were therefore harvested much earlier. Sustained, moderate temperatures occurred until the end of March and resulted in effective plant functioning and full maturity in late cultivars.
Cover crops were well established and have particularly accumulated good biomass during August, during which the region experienced higher temperatures. This ensured effective weed suppression. Historic problem areas will maintain a high population of snails, although they were less of a problem due to a drier spring.
Fungal disease pressure was relatively high after the good rainfall during October and various generations of downy mildew were present from the flowering and berry set stage to late summer. Producers who didn’t modify their spraying programmes and frequency thereof experienced both crop losses (wilting of flower bunches) as well as effective canopies loss. Pinotage and Merlot were particularly affected by this.
Mealy bug, weevil and katydid outbreaks were somewhat higher than in the previous season, although it was still under control. The growth season was characterised by good, even shoot growth which resulted in excellent canopies with sufficient capacity to ripen the crops.
Seasonal rainfall during the growth season as well as moderate temperatures resulted in good vigour, whereas the high wind speeds towards the end of the summer kept the vigour and berry sizes under control.
The early cultivars were harvested up to two weeks earlier than usual. However, the ripening pace slowed down towards the end of the harvest season and late cultivars were harvested at the normal time, due to the cooler temperatures and significant load. The bigger harvest and accelerated maturation placed some pressure on cellar space halfway into the harvest period.
GRAPE AND WINE QUALITY
Early indications of the wine quality are looking promising. Grape analyses of the early cultivars generally showed higher acidity levels, thus resulting in less addition than the normal amount of acidity at the cellars. Chenin Blanc stood out particularly.
Wine laboratories confirmed normal yeast assimilable nitrogen (YAN) values, which could be ascribed to good, healthy canopies as well as effective irrigation scheduling and fertilisation programmes. Colour and tannin analyses of the red wines are appearing to be much better than in 2019 and the producers are expecting full-bodied wines with intensive flavour profiles.
Average to below-average juice recoveries were reached due to relatively small berry sizes.
Article from Vinexion.com
Published with permission from WoSA