Known also as noble rot, botrytis cinerea is unique in that it is actually a sought-after element in many wines including Sauternes and the Eisweins of Germany. This is because of the increased richness and complexity that the penetrating mold adds to the flavor of the resulting wine. This added flavor is partially a result of the botrytis shriveling the grapes, henceforth concentrating the level of remaining moisture.
boh-TRI-tihs sihn-EHR-ee-uh] A beneficial mold that causes grapes to shrivel and sugars to concentrate, resulting in sweet, unctuous wines; common botrytis wines include French Sauternes, Hungarian Tokay, and German beerenauslese. (see Botrytis cinerea)
Botrytis is a fungus that attacks grapes. In bad weather conditions (cool, damp, poor air circulation around the grapes), it can ruin the crop in the guise of "grey rot" or pourriture grise. When conditions are perfect (moisture as well as warm autumn sunshine), it can transform grapes in a positive way and produce astonishing sweet wines. In this manifestation, it is known as "noble rot" or pourriture noble.