South Australia 2019 vintage report

2019, although warm, was more moderate than 2016 and 2018.

GROWING SEASON HEAT SUMMATIONS (°C DAYS)

As well as being significantly warmer than average, the last four vintages have been significantly drier than average with the exception of 2017.

% OF AVERAGE GROWING SEASON RAINFALL

In summary, 2019 is a very high quality, warm and dry vintage, cooler than 2016 and 2018 and perhaps honouring the time-tested aphorism, 'The best quality wine is made from a cool climate vineyard in a warm year.'

Tiers Vineyard Chardonnay (Piccadilly Valley, Adelaide Hills)
Hand harvested on 18 March, 1.5 weeks ahead of average. The crop level was 60% of average at 4 t/ha. The fruit was in perfect condition, in part reflecting the dry growing conditions. The at-harvest analysis of Tiers fruit was:

23 Brix, pH 3.1, TA (cold stable) 6.3 g/l, malic acid 2.83 g/l.

Foggy Hill Vineyard Pinot Noir (Parawa, Fleurieu Peninsula)
Hand harvested on 8 and 9 March, 1.5 weeks ahead of average. The crop level was 5.5 t/ha as expected. The fruit was in perfect condition and the in-vineyard analysis was:

23 Brix, pH 3.87, TA (cold stable) 6.1 g/l and malic acid 3.47 g/l.

Whalebone Vineyard (Wrattonbully)
Whalebone Vineyard Merlot was hand harvested on 20 March, Whalebone Vineyard Cabernet Franc was hand harvested on 1 April and Whalebone Vineyard Cabernet Sauvignon was hand harvested on 9 April. Yields were small for Cabernet Sauvignon at 2.5 t/ha and more normal for Merlot and Cabernet Franc.

In growing season 2019, after good spring rains the weather dried up from January on and Wrattonbully had 71.9% of growing-season rain. The hotter than average months were December, January and February and the ripening occurred in average temperature conditions in March and April. The fruit was in perfect condition with moderate sugar content (Brix) and acids and great colour and flavours.

Heat Summation Tables for The Tiers, Foggy Hill and Whalebone Vineyards

THE TIERS

FOGGY HILL

WHALEBONE

MUSINGS

Despite 2019 vintage joining the ranks of the warmest vintages since 1960, the grape analysis and quality did not reflect that. This is also true, to a slightly lesser extent, for the even warmer 2016 and 2018 vintages. In fact, the grape analysis for each of the last four vintages has been remarkably similar at the Tiers and at Foggy Hill and harvest dates have differed only in the very late, cool, wet spring 2017 vintage, the latest on record for both Tiers and Foggy Hill. Harvest dates have also been remarkably similar in the Whalebone Vineyard, including in the relatively cooler 2017 vintage.

The analysis for the 2017 grapes did not reflect a major difference with the warmer and much earlier 2016, 2018 and 2019 vintages. Malic-acid level is a very good proxy for the heat received by the grapes during the growing season because its degradation depends on the temperature and time on the vine. The malic-acid levels in all four vintages across both vineyards are similar and elevated rather than depleted despite the abnormal warmth. Similarly, in very warm regions and seasons, the sugar level in the grapes can be severely elevated, but in all four vintages and both vineyards the sugar levels remained modest despite the abnormal warmth.

HARVEST DATES AND ANALYSIS

With the expected very hot 2016 being slightly higher Brix and lower malic acid and the cooler 2017 having slightly lower Brix and higher malic acid, the grape analysis and quality for all of these vintages is remarkably similar given the very significant departure from the average heat summations depicted in the heat-summation tables above. Analysis from the Whalebone vineyard was also showing great consistency from vintage to vintage with low malic-acid levels.

THE BIG QUESTION?

Expecting the worst of these very warm vintages, high sugars, low acids, overripe flavours and coarse textures, my fears have been unfounded. All of these vintages from Foggy Hill Vineyard and Tiers Vineyards express fresh Pinot Noir and Chardonnay varietal characters, with low to moderate alcohols and lovely acid balances and for the Pinots refined tannins. The recent vintages in the Whalebone Vineyard demonstrate the resilience of the Bordeaux varieties to the warmer climate.

WHY?

This an existential question as we face more higher-temperature vintages. It is the question at the heart of the speculation about regions having to change varieties as they progressively warm. 

Cause and effect are never simple relationships in nature, and I have searched the numbers and my soul for the answer for this apparent uniformity and moderation of temperature effects across these disparate and very warm vintages. 

Prompted by a casual conversation with my hero Dr John Gladstones, I decided to put the night-temperature component of the heat summations in at the long-term average rather than the higher recorded actual amount. This had the effect of bringing the heat summation of the warmer vintages closer to that of the cooler ones, explaining the less than expected differences in composition and quality between warmer and cooler vintages. My rationale is that night temperatures are very moderate and have marginal influence on vine catabolism/anabolism and of course not on photosynthesis. It is day temperatures that dramatically affect fruit composition and in the case of Chardonnay and especially Pinot Noir high temperatures result in a loss of the quality and intensity of varietal character.

Here’s what happened in Tiers Vineyard and Foggy Hill Vineyard!

COMPARISON OF TOTAL TO AVERAGE NIGHT TEMPERATURE ADJUSTED HEAT SUMMATION (°C-days)

The adjustment for the negligible effect of night temperature on grape composition has the effects of diminishing the difference between 2017 and the warmer vintages and makes the warmer vintages much more similar one to the other and more moderate to answer the description of the 'best wine comes from the warmer vintages in a cool site', rather than a hot vintage destroying the quality from a cool site.

My second thought was to compare the critical-to-quality, post-veraison heat summations for each of the vintages and sites. Just as day temperatures are critical to the metabolism of the vine, the post-veraison ripening processes are critical to final grape composition and quality. February and March are when nearly all of the colour, sugar and flavour are developed in the berries and when the tannins are modified to be less bitter and astringent.

FEBRUARY + MARCH HEAT SUMMATIONS (°C-DAYS)