Botrytis

Botrytis cinerea, often called "noble rot", is a fungus that plays a double-edged role in winemaking. It is especially important in the production of sweet wines such as Sauternes and Tokaji, but it can also turn up in Champagne, although its effects there are much less prominent.

Botrytis cinerea and its role in winemaking

Botrytis cinerea is a parasitic fungus that can infect grapes. Its effect on the fruit depends heavily on the weather and conditions in the vineyard. In favourable conditions, such as damp weather and warm temperatures, the fungus can attack the grapes and lead to what is known as "noble rot". While this process partly destroys the grapes, it also concentrates the sugars and aroma compounds in the remaining fruit, producing very intense and complex wines.

Noble rot in sweet wines

In the making of sweet wines, Botrytis cinerea is of great importance. Grapes affected by the fungus dry out and concentrate their sugar and acid levels. These concentrated grapes are then pressed to produce very sweet wines, which often show a rich aromatic profile ranging from honey and dried fruit to spice and floral notes. Wines such as Sauternes from Bordeaux or Tokaji from Hungary are famous examples of what botrytised grapes can achieve.

Botrytis cinerea in Champagne production

Champagne relies mainly on Pinot Noir, Pinot Meunier and Chardonnay, and here Botrytis cinerea is much less welcome. The quality of the grapes is of decisive importance, and an attack of noble rot can compromise the freshness and purity of the champagne.

That said, in years with particularly wet and warm weather, some producers may choose to work with botrytised grapes if they want to use them deliberately for certain styles of champagne or for ageing in special cuvées. Such grapes can contribute subtle, complex aromas, which are then balanced in a carefully chosen production process.

Chateau de Bligny Champagner

Controlling Botrytis cinerea

Keeping Botrytis cinerea in check requires precise vineyard management. Good airflow and avoiding excess moisture are essential to hold the fungus at bay. In very damp years, fungicides may be needed to protect the grapes from infection.

Summary

Botrytis cinerea is a fungus that can have both positive and negative effects in winemaking. While it is indispensable for making noble sweet wines, it is less welcome in Champagne, because its presence could compromise the freshness and purity of the finished wine. Vineyard management and the weather play a decisive role in controlling this fungus, and ultimately shape the quality of the grapes and of the wines and champagnes made from them.