There are at least eighty different fungi that can attack grapes, and nearly all of them have effects that are catastrophic. Under the right circumstances, however, when most winemakers learn that their grapes have been "attacked" by the fungus known as "Botrytis Cinerea", they find it hard to hide their joy. Botrytis, it should be understood, is a beneficial fungus that can transform an ordinary wine into a great one.
In its natural form, botrytis, which is sometimes referred to as "noble rot", appears regularly in very few locations. These include Sauternes and Barsac on France's Garrone River; the Hungarian area of Tokay; certain spots on Germany's Rhine and Mosel Rivers and, occasionally in the Piedmont area of Northern Italy. In California and Australia, botrytis is rarely found in nature but the spores are sometimes sprayed on vines that have been set aside in isolated buildings, thus allowing a somewhat artificial but controlled development of the rot.
Botrytis appears periodically in other locations, but rarely affects enough grapes to allow for a commercial bottling of the wines. In Israel, for example, botrytis has appeared at least five times in the last fifteen years but only once, in 1988 were there enough grapes to produce a sizeable amount of wine.
In order to gain the maximum advantage from botrytis, grapes must be left on the vines quite late in the season. Then, with the combination of cool morning mist and hot, clear afternoon sunshine, the fungis can enter the grape. If the grapes are perfectly healthy the "attack" is entirely beneficial.
The grapes shrivel, first turning grey and then warm violet-brown. The skins are reduced to a mere pulp, the grapes lose more than half of theirweight but less than half of their sugar. The juice is thus concentrated, extremely sweet and rich with glycerine. Although grapes in this condition may be repulsive to look at, they arecapable of producing the special taste and qualities much sought after in sweet dessert wines.
One folktale tells us that the beneficial aspects of noble rot were first discovered by Marquis de Lur-Saluces, the owner of Chateau d'Yquem in the region of Sauternes.
According to this charming but not at all true story, the Marquis had to make a trip to Russia (another version of the story says he went on a hunting trip) and left orders that the grapes were not to be harvested until his return. Because he returned late in the year the grapes had become overripe and were totally contaminated with the mold. To everyone's great surprise, the rotten grapes produced a wine so superb that it the wines of d'Yquem have become world famous and, in the best years, extraordinarily expensive.
The less romantic truth is that botrytis was introduced to Chateau d'Yquem in 1847 by Alfred Focke , the German owner of a nearby chateau, La Tour Blanche. Focke had been experimenting for more than a decade with methods already used to make the great sweet wines of the Rhine River valley. Whether the greatest wines resulting from botrytis are those of Chateau Yquem or German Trockenbeerenauslese is a matter of personal taste. Both are big and luscious, have an intense rich texture, flowery bouquet and an unmatched elegance.
The often magnificent wines that result from exposure to botrytis need no apologies for their sweetness, which has been achieved only at great expense and difficulty. These wines are meant to be drunk as aperitifs, with fresh foie gras and with desserts such as cheesecake, ripe fruits and sharp cheeses.