Definition: botrytis

Legend has it that Romain Bertrand, nephew of the Lur Saluces family, then owners of Château d'Yquem, postponed the harvest in 1847 due to a hunting expedition in Russia. It was then that he realised the beneficial effects of noble rot.
In the Sauternes region, although late harvesting had been practised since the early 19th century, it was this exceptional vintage that made Château d'Yquem famous and, as a result, brought the greatness of Sauternes wines with their noble rot to the attention of the Russian court, dethroning the Tokays of Hungary. What is botrytis? Grey rot, also known as botrytis or noble rot when it is sought after, is caused by a phytopathogenic fungus, Botrytis cinerea. In some regions, it attacks not only plants but also grapes. From a botanical point of view, it belongs to the ascomycetes. While this fungus can cause considerable damage to market gardening and agriculture, wine production in certain wine-growing regions could hardly do without it. In autumn, under the effect of morning mist, botrytis gradually develops on the grapes. Its spread is encouraged by increasingly dry and warm weather around midday, which makes the skin of the grapes permeable, leading to the evaporation of the water they contain. Their sugar content gradually increases and their aromas change. Oenologists often mention a hint of fennel which, combined with fruitiness and sweetness, has a positive influence on the aromatic characteristics of wine made from such grapes.
Other methods used to reduce the water content of grapes and thus increase the Oechsle degree of the must include harvesting frozen grapes to produce ice wine and drying grapes harvested during the winter in well-ventilated rooms to produce Amarone. However, none of these methods gives the wine the typical fennel aroma of noble rot.

Vinification of botrytised grapes
Due to the high sugar content of the grapes, it is no longer possible to carry out classic vinification. The cellar master must therefore add special yeasts to the highly concentrated must, which can withstand such an environment and are capable of converting a large part of the sugar into alcohol. During this process, particular care must be taken to ensure that the temperature of the must does not drop too low, in order to prevent premature interruption of fermentation. For this reason, heat is often added during this phase until the wine has reached the desired alcohol and residual sugar content.
It should be noted that not all botrytised grapes are used to produce sweet wines. Although some dry white wines from Germany, Austria and Hungary have a very subtle fennel aroma, which suggests the use of botrytised grapes, only a small portion of the harvest affected by noble rot is used to produce these wines. That said, botrytis gives the wine a very distinctive taste that is highly appreciated by connoisseurs.

Regions producing wines from botrytised grapes
While the reputation of Sauternes sweet wines is well established, it is not the only region to benefit from noble rot. Hungary also produces extraordinary sweet wines, the famous Tokays, which are just waiting to regain their dominant position in this segment. Germany also produces great sweet wines from botrytised grapes, with the only difference being that this is not specified on the labels. Austria is slowly making a name for itself among the greats: in Burgenland, for example, around Lake Neusiedl, Botrytis cinerea benefits from ideal conditions for development. Robert Parker, the renowned American critic, consistently awards top marks to several wines from this region year after year. Finally, Canada produces excellent ice wines from late harvests at relatively high temperatures.

Grape varieties used
In Sauternes, three grape varieties are used: Sauvignon Blanc, Muscadelle and Sémillon. Hungarian Tokays are produced from Furmint, while in Germany and Austria, different varieties of Riesling are used to make sweet botrytised wines. But other countries also produce wines of this type, such as Switzerland, where they carry the additional designation "sélection de grains nobles" (selection of noble grapes).

Serving botrytised sweet wines
In France, Sauternes is traditionally served with a starter of pan-fried or poached goose liver. That said, after a hearty main course, Tokay, Sauternes and other sweet botrytised wines are wonderful with blue cheeses such as Roquefort or Stilton, offering a pleasant alternative to Port and Madeira, which are also very popular.

See noble rot and grey rot.

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