What happens when botrytis affects red grapes?
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Dear Dr. Vinny,
I've only heard of dessert wines being made from botrytis-affected Sémillon, Sauvignon Blanc, Viognier, Chardonnay, Welchriesling, Scheurebe, etc. I've wondered if botrytis can infect red grapes and, if so, what's the outcome? Has anyone ever tried to make such a wine? I know of "late-harvest" reds, and wines made from dried red grapes (like Amarone), but not of any botrytized reds.
—Danielle, New York
Dear Danielle,
Good question. Botrytis, the “noble rot” that can turn grapes into shriveled, nearly raisinlike grapes that are the source of some terrific dessert wines, are usually only mentioned in the context of the grapes you mentioned, and those grapes are white.
Botrytis also comes up in the context of red wine grapes, but typically not in a good way. Tightly clustered grape bunches like those of Pinot Noir can be susceptible to botrytis, especially in cool, damp years. You can make a dry (non-dessert wine) with botrytis-affected grapes, but it can impart an earthy note that reminds me of horseradish, along with a honeyed note. Winemakers usually thin out the botrytis-affected bunches before harvest.
Even in the most prime conditions, botrytis can lead to a microbial soup of problems. And red wine grapes—which would typically have a higher pH—would be more at risk to develop further bacterial infections down the line. I’ve also heard that botrytis has the side effect of bleaching out the pigments in red wine grapes, so the resulting wines look anemic and gray—not very appetizing.
I don’t doubt that there are some brilliant winemakers making late-harvest wines from red wine grapes that have a positive effect from botrytis, but for the most part, botrytis is never used in a positive connotation with red wine.
—Dr. Vinny
