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The effects of botrytis cinerea

Botrytis cinerea is a microscopic fungus responsible for the magic of Sauternes. When it appears, in autumn, it consumes part of the sugar and acidity in ripe grapes. Little by little, the grapes are transformed and become more concentrated due to evaporation, thereby enhancing the aromas and the overall sugar content, as well as inducing a subtle alchemy of the juice.

The men and women at Fargues work hard all year round to domesticate this phenomenon by ploughing and looking after the soil, lavishing meticulous attention on the vines, and by their expert intervention when the grapes are overripe.
At this point, the grape skins become thinner, but do not crack, enabling the fungus to work its magic on the juice. Filaments pierce the skin without damaging it. Botrytis develops both inside and outside the skin, without leaking any juice, and without oxidation. This is when a miracle occurs, a veritable miracle underneath the grape skins. The berries become browinsh and shrivelled, concentrating maximum sweetness and acquiring rich candied fruit flavours and floral aromas.

Botrytis consumes acidity and some of the sugar in ripe grapes. Thanks to this concentration, the grapes gradually become “botrytised” and their sugar level rises to 20-21 degrees potential alcohol, or the equivalent of 350 grams per litre. Noble rot, present all year long on the vines, spreads in autumn due to the effect of a unique microclimate that subtly alternates between humidity, sunshine, and wind.

At Fargues, the aim of all the patient work in preparing the soil and looking after the vines is to control this botrytis, and to contain it to prevent it from acting before the grapes are sufficiently ripe. This exact same botrytis can also be a dangerous enemy, a “phytopathogenic” parasite responsible for grey rot, a scourge that winegrowers everywhere fight against. It only becomes beneficial when the grapes have a high sugar level. The challenge is thus to make sure that botrytis is present and ready to act, but that it does not do so before the grapes are ripe.

A good understanding of nature, the terroir, the microclimate, and the vines is thus essential to fight against the premature spread of botrytis – but, on the other hand, to encourage its propagation when the grapes have reached just the desired degree of ripeness… The development of botrytis must therefore be carefully watched.  Several parameters need to be taken into account: the vigour of the vine, its nourishment via the rootsock, the density of the leaf canopy, the degree of humidity around the grapes, as well as attacks by insect pests such as grape berry moths… These factors need to be controlled to avoid the arrival of early rot, which can cause a great deal of damage.

Everything possible is done to enhance this marvellous, magical phenomenon – noble rot – and to make the most of it. Château de Fargues’ fundamental ambition is to work with nature to make an exceptional wine, the fruit of the synergy between man and nature.

The transformation of grapes by botrytis calls for an important sacrifice: any grapes attacked by the wrong kind of rot must be discarded. It is not at all rare to reject half the crop, or even more (2012 is the most recent example).
An average crop at Fargues produces about 1,000 bottles a hectare, i.e. the equivalent of one glass per vine… compared with one bottle per vine for a dry white or the usual sort of sweet white wine. This is because, on top of botrytis, passerillage (raisining) also occurs. The juice becomes very concentrated and the grapes lose 2/3 of their volume.

This is the exact opposite of an industrial process, and is the paradox of Sauternes… The keys to this extraordinary transformation are a perfect balance between man and nature, followed by extremely careful picking.

At Fargues, quantity is never the goal – quality must always prevail, and we do our utmost to capture the wine’s tremendous aromatics and put them into bottle.