Here is one perspective on vintage 2017 in Hawke’s Bay… More will follow on this site. Watch this space…
Two words beginning with ‘c’ sum up vintage 2017 in Hawke’s Bay for Bordeaux oenologist Ludwig Vanneron, consultant to the small Waimarama Estate: challenging and complex. I asked him to share his thoughts on how he responds to heavy rainfall pre-harvest on late ripening grapes. Here are his thoughts.
“When it’s rainy in Bordeaux, we say it is better to pick grapes more ripe under rain than green (and dry) with sunshine.
“There are actually several factors to take into account: dilution (water makes berries bigger), tightness (compacité) of bunches, risk of burst, split, and rot infection (where it starts, and how fast it grows depending on the vineyard, the plots and the grapes).
“The look, analysis and weight of grapes can give an idea of the dilution effect. If we must pick green grapes like unripe Cabernet (high pyrazine content), fining, oaky adjuncts and micro-oxygenation could improve the wines.
“Bursting effects and rot infection require high attention and care. Everyday we have to take a look in the vineyard and check how it grows. If it is located only in some bunches, which are very tight, and weather is forecast to improve, then a healthy sort by hand before picking can be done. Then, another problem is the cost, but making good or very good wines in bad conditions is always more expensive.
“Rot infection requires a change to enological practices by taking care of aeration and oxidation effects, due to laccase compounds produced by botrytis. If there is lots of oxidation, mostly from the beginning, as soon as must is free out of the berries, then laccase starts and we lose aromas and colour degradation is more sensitive as well. So adjunctions of specific tanins (proanthocyanidic) are required, and fermentation needs to start quickly by putting yeasts straight into the vats. The goal is to fix the colour, as much as possible, by using other types of tannins and adapted winemaking practices.”
What is the biggest challenge in a rainy vintage when you would like to leave grapes hanging on the vines for longer?
“Our only goal is to make the best wine we can from the best grapes possible. The first point to consider is the work in the vineyard and how the vines were managed during the growing season to maximise healthy ripe grapes.
“Among the keys are: well timed pruning, the spread of bunches from one vine to the next, the removal of young shoots (pampres, in French), the quality of tucking on trellising system (main shoots have to be straight up, no crossing), removal of lateral shoots, leaf plucking, crop thinning, applications of specific products (natural defense stimulators, among others) and timing along with quality of sprays for treatments.
“The type of grapes is important to consider. If red, they may be able to wait, in the anticipation they could become more ripe, even if the risk of rot infection is high (natural tanins in the berries act like a fence against botrytis attack). For white grapes, we must have a different approach as we are looking after aromas first but rot produces laccase and early fining of must (at settling) helps to create clean juice early, which is a good start for keeping varietal flavours.
“To leave grapes hanging on the vines for longer, the aim is to reduce green characters. Pyrazines are at a higher level during veraison, then they decrease week after week during maturation. Merlot is easier as pyrazines are not as high as they are in Cabernet, and the maturation time required to get ripe grapes is approximately 45-50 days after the colour change of veraison whereas Cabernet Sauvignon’s is 60-70 days. This makes it more difficult to get lower amounts of pyrazines in berries.
How can you eliminate green pyrazine flavours from Cabernet?
“One way is to remove the first leaf in front of the bunches at an early stage (2 to 3mm berry size). Then by doing this practice, you “cut” the factory of pyrazine production, and the level at the veraison time is lower, making easier to reach ripening at the end because we start with lower quantities of pyrazine, so we can expect lower amounts when the grapes are ripe.”
What are the key differences in the winemaking process for Cabernet grapes harvested earlier than ideal?
“The risks are pyrazine and green flavours, including green and harsh tannins. Specific fining like PVPP, the use of micro-oxigenation, combined with external tannins adjuncts (toasted oak chips) and adapted enological practices during the winemaking roadmap will make the wines taste better.”
Will this impact on pruning and crop levels for next year?
“No. Each vintage is different and has its own characteristics. Frost or hail are much more annoying for the years that follow, compared to rain.”