There are hundreds of fungi that attack grapes, and the majority of them have effects that can be disastrous to a vineyard. A fungus called Botrytis, however, is a beneficial fungus that becomes magical and noble.
Botrytis is a mold that develops on grapes. When carefully cultivated, Botrytis causes the grape to shrivel, concentrating, and intensifying both the sugar and flavor. In addition, the acid levels remain high, which prevents the resulting wines from being too sweet. It also changes the makeup of the grape, so the wines made from grapes that have the botrytis fungus are not just sweet but have an intense honey flavor. Most winemakers are exhilarated when noble rot descents on their grapes because it gives those fruit from which to make very elegant, intensely flavored dessert wines.
Few winemakers will attempt to make botrytis wines. The fungus requires specific weather conditions and the winemaker has to leave the grapes on the vine until late fall, risking loss of the entire crop.
The Bordeaux region of France has a reputation founded on Botrytis. Because of the close proximity to the Atlantic Ocean, the Bordeaux region has extremely humid and misty mornings relieved by sunshine in the afternoons. These weather changes of dampening and drying off are an ideal climate pattern for encouraging Botrytis. The Bordeaux region winemakers take this process seriously, to a point where the winemaker will hand pick the shriveled grapes, leaving the others on the vine before going through the vineyard again. This, together with aging, explains the drop-dead prices of good Bordeaux.
The wines that result from exposure to botrytis need no apologies for their sweetness. They are meant to be drunk as aperitifs, with desserts, fruits, and sharp cheeses.
Contributor: Kana Oldara (Tacoma, WA)