Botrytis Cinerea

Botrytis cinerea or “noble rot” is Latin for “grapes like ashes.” It is a fungus that dehydrates grapes by piercing their skins and feeding on the juice and sugars.

Botrytis Cinerea or Noble Rot Sweet Wine Production

Although these grapes are not visually pleasing, they have concentrated sugars and produce extraordinary sweet wines. Because the amount of juice extracted from these grapes is extremely low, it takes a lot of vines to produce a small amount of wine.

It is also very difficult and labor intensive to pick the grapes. The fungus attacks grapes unevenly and several tris (pickings) are needed to pick each grape at the right time.

Naturally, this leads to high prices. Located in Sauternes, Chateau d’Yquem is the world’s leading producer. Their wines go for several hundred dollars per bottle.

Vineyards prone to developing Botrytis cinerea are often on hillsides located near bodies of water. Botrytis cinerea requires humid, foggy mornings followed by dry, sunny afternoons. If the weather is too wet, Gray rot forms when vineyards are wet for too long, and will ruin the fruit.

In California, Riesling, Sauvignon Blanc, and Gewurztraminer are the most popular varietals used to make Botrytis cinerea wines. However, noble rot will infect any varietal if the conditions are right.

Botrytis cinerea does not only target grapevines. While it is a problem for most other fruits, it is normally welcomed by grape growers. However, it can be a scourge to grapes. When it appears too early in the growing season before the grapes are ripe, it can literally destroy a harvest.

The fermentation process of these wines can be extremely long. Grapes infected by Botrytis cinerea are hard to ferment because the mold naturally kills yeast. Measures have to taken to protect the yeast so fermentation can occur.

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