Botrytis: when a rotting vineyard is a good thing

“Noble Rot” is a fungus that shrivels and dries wine grapes. Noble Rot, or Botrytis cinerea, is an Ascomycota within the Fungi kingdom. You’ve met it before. You can thank Botrytis for those moldy strawberries you recently threw out. Botrytis is related to the penicillin used in antibiotics, fungus used to make blue cheese, and the fungal culprit of athlete’s foot. Yup. Noble Rot shares a house with athlete’s foot. But unlike its unpleasant cousin, the discovery of Botrytis in a vineyard is cause for celebration. Why the heck would vintners celebrate a fungus related to athlete’s foot taking over their vines?

When Botrytis infects grapes, some pretty spectacular things happen. Highly desired wines like Sauternes and Spätlese Riesling owe their existence to Noble Rot. So how did fungus earn a seat among the world’s best wines?

Botrytis intensifies sweetness

Botrytis dehydrates grapes and concentrates sugar levels. Wines made from Noble Rot grapes, often called botrytized wines, are sweeter, more viscous, and sometimes even pack more alcohol.

Botrytis improves flavor

Botrytized wines contain notes of honey, ginger, and beeswax.

What do Noble Rot/botrytized wines taste like?

• Honey
• Beeswax
• Ginger
• Honeysuckle
• Sweet
• Bitter finish

What should I eat with botrytized wines?

• fruit
• cheesecake
• sugar cookies
• panna cotta
• crème brûlée
• Light desserts

Botrytis wine terms

• botrytized wines: wines produced with Noble Rot grapes
• Tris: “selections,” referring to hand-picking of the best botrytized grapes
• aszú: Hungarian botrytized wine (also called Tokaji or Tokay)
• Sauternes: French botrytized wine
• Beerenauslese/Trockenbeerenauslese: botrytized wines from Germany and Austria

Names for Noble Rot

• pourriture noble (France)
• Edelfäule (Germany)
• Muffa nobile (Italy)
• Aszúsodás (Hungary)

Where does Noble Rot happen?

Two “types” of Botrytis exist, and both are totally dependent on moisture. Botrytis’ more sinister permutation, grey rot, totally ruins grapes; Noble Rot is welcomed. Both are the exact same fungus. How does that work?

Botrytis can either be inoculated artificially or naturally. Both grey rot and Noble Rot require initially moist conditions to manifest, so vineyards close to water or with high rainfall are more likely to contract Botrytis. If the wet weather persists pernicious grey rot renders the grapes useless. If conditions dry out, the grapes raisin, resulting in the beneficial form of Botrytis. At this point grapes lose water rapidly while retaining sugar, making a concentrated, sweet grape perfect for making high-alcohol and dulcet-smooth dessert wines.

Viticulture’s long relationship with mold

No one likes rot, especially when the adjective “fungal” is slapped on like an insult to injury. Rot in all its permutations happens to all good things, even wine. As long there’s been wine, vintners have made war against decay and rot. Besides Botrytis, mold is something vintners avoid like the plague. Powdery mildew devastates vineyards across the world. Cork taint is an airborne fungus that ruins wines after bottling. Black mold is extremely common companion to bottles and barrels aging in dark, wet cellars.

Noble rot was first mentioned in Hungarian wine literature as early as 1576. Germany has its own creation story of Botrytis, which goes something like this:

The year was 1775 and a messenger carrying orders to harvest grapes at Schloss Johannisberg was just robbed. The Riesling makers at Schloss Johannisberg, afraid of harvesting the grapes without permission from the estate owner, delayed harvest by three weeks, enough time for Botrytis to set in. The grapes, considered worthless, were given to local peasants, who created a surprisingly delicious wine which became know as Spätlese, or late harvest wine.

Some botrytized wines to try

Ready to try some botrytized wine for yourself? Here’s a list of “rotten wines” you’ll be sure to love!

Chateau Guiraud Sauternes 2005, Sauternes, France ($59.99)

Verglas Icewine 2015, Stoneboat Vineyards, British Columbia ($37)

Kracher Cuvee Beerenauslese (375ML) 2017, Burgenland, Austria ($36)