A bunch of Riesling grapes after the onset of noble rot. Thedifference in colour between affected and unaffected grapes is clearly visible.

The most expensive winesmade from Riesling are late harvest dessertwines, produced by letting the grapes hang on the vines well past normalpicking time. Through evaporation caused by the fungus Botrytiscinerea ("noble rot") or by freezing, as in the case of ice wine (inGerman, Eiswein),water is removed and the resulting wine offers richer layers on the palate.These concentrated wines have more sugar (in extremecases hundreds of grams per litre), more acid (to give balance to all thesugar), more flavour, and more complexity. These elements combine to make wineswhich are amongst the most long lived of all white wines. The beneficial use of"noble rot" was discovered in the late 18th century at Schloss Johannisberg. Permission from the Abbey of Fulda (which owned the vineyard) tostart picking the grapes arrived too late and the grapes had begun to rot; yetit turned out that the wine made from them was still of excellent quality