The thick hairy greenish-gray mold that shrivels grapes for Austria's world famous sweet wines releases a cloud of fungus spores as grapes are manually harvested. Just how the murky, viscous must pressed out of these raisined grapes is transformed into luscious clear golden nectar seems to border on alchemy.

You can stand with your head above water in the entire 320-km Lake Neusiedl in Burgenland. Over 2,000 hours of sunshine during growing season not only guarantee physiologically ripe grapes, but also warm the Pannonian steppe lake to bath temperature. This warm, humid climate with its long autumns of morning fog and afternoon sun ensures an ideal environment for the benevolent noble rot in the vineyards near the lake.

Botrytis cinerea is the name of the fungus infecting grapes in increasing degree for the wines labeled Auslese, Beerenauslese, Ausbruch, and Trockenbeerenauslese. On the left shore in the Neusiedlersee-Huegelland district, Rust has been famed for its botrytis-affected Ausbruch since 1681, when the city bought its rights for self-government for 60,000 gulden in gold and 30,000 liters of this noble sweet wine. On the right shore, where the lake makes a bend, the Seewinkel area in the Neusiedlersee district is particularly known for its Trockenbeerenauslese.

There is a wide band of grass and reeds around Lake Neusiedl providing a natural habitat for a very large population of birds. "Eight kilometers of nets per hectare are needed to save all of those sweet grapes from becoming very expensive bird feed," says the Seewinkl sweet wine specialist, Alois Kracher. Expensive indeed, for yields are often as low as 10 hectoliters per hectare in Kracher's oldest vineyards with 45 year old vines. As nets are rolled away at harvest, a fruit zone is revealed that has intentionally not been freed of all foliage. Several passages over a period of weeks are required to hand select only those grapes completely infected and shriveled by noble rot.

Sandy soils are found in the marshy Seewinkl area on the east side and the area is sprinkled with several small lakes and ponds that support a consistently reliable and very homogeneous botrytis. The spectrum of grape varieties is wide, but Welschriesling, Bouvier and Saemling dominate. The rather neutral Bouvier is slowly being replaced by Burgundian varieties. A lusciously sweet Pinot Gris from the Umathum or Lentsch wineries offer delicious examples. Other wineries like Julius Hafner make world-class dessert wines from aromatic grapes like Muskat Ottonell and Traminer. On this side of the lake, the sweet wines are predominantly varietals that usually reach well over the minimum 30 degrees KMW (sugar weight content) required for Trockenbeerenauslese. Traditionally, the style is highly concentrated with very high residual sugar and low alcohol.

On the western shore in Neusiedlersee-H|gelland, the celebrated Ausbruch has a long tradition. Here, too, the soils are predominantly light and sandy with most sweet wines coming from vineyards along the lake near Rust with a few pockets of suitable microclimates for noble rot in the hinterland. The sweet wines on this side of the lake are often blends. The Burgundian grapes Pinot Blanc, Pinot Gris, and Chardonnay dominate supported by Neuburger, Muscat Ottonel, Welschriesling, Saemling, and the rare Furmint variety. In the traditional production of Ausbruch, fresh must from non-botrytized grapes from the same vineyard were added to the fermenting wine. "All the wine books still describe the Ausbruch being made that way, but no one uses that method any longer," says winemaker Paul Schandl. In modern vinification, the addition of about 5% healthy late harvest grapes may be added to the must to increase acidity and sink the sugar content to lie between 27 and 33 KMW. With so much sugar and so little liquid in the must, this helps encourage the fermentation. The result is a wine with higher alcohol and and acidity with a more vinous character than the wines from the Seewinkel. "I like to give my wines a very light touch of oxidation," says Kurt Feiler, winemaker at Feiler-Artinger, "They not only gain a beautiful amber color, they also increase greatly in complexity."

The Neusiedlersee district's leading winemaker Alois Kracher puts the grape bunches, stems and all, through a gentle crusher producing a thick jammy mass of syrup, slippery grape skins, stems and seeds, while Heidi Schroeck prefers to use whole berries only. Some winemakers like the complexity gained by maceration, while others, seeking more fruit and freshness, will press immediately after crushing. Pressing generally occurs in a gentle pneumatic press and is always a very slow process that takes several hours; the mash must be loosened between three pressings to coax murky viscous must to ooze out. The fermentation of an Ausbruch may cease after three months, whereas a Trockenbeerenauslese can ferment for over a year. With both wines, the winemaker can choose between fermentation vessels, and depending on the grape variety and desired style, the wine will be matured in large oak casks or new oak barrels.

In no other wine region in the world does noble rot attack grapes so consistently. While botrytis visits the great sweet wine areas of France and Germany only every few vintages, it is rare for the Neusiedlersee districts to have a year without it. Due to the certainty of the conditions, production of noble sweet wines is reliable and the supplies are abundant. In years where noble rot appears in other Austrian wine districts, wineries profit from the country's wide spread sweet winemaking expertise. Many estates, like Willi Opitz, also make other non-botrytized dessert wine specialties like Strohwein and Eiswein as well.

Excellent sweet wines are always expensive to make, but Austrian sweet wines can still be found at a fraction of the price of their French and German counterparts.