Definition: noble rot 2

Legend has it that Romain Bertrand, nephew of the Lur Saluces family, then owners of Château d'Yquem, postponed the harvest in 1847 due to a hunting expedition in Russia. It was then that he realised the beneficial effects of noble rot.
In the Sauternes region, although late harvesting had been practised since the early 19th century, it was this exceptional vintage that made Château d'Yquem famous and, from there, brought the greatness of Sauternes wines with their noble rot to the attention of the Russian court, dethroning the Tokays of Hungary.
What is Botrytis cinerea?
A certain type of rot, also known as botrytis or noble rot when it is sought after, is caused by a phytopathogenic fungus, Botrytis cinerea. In certain regions, it attacks not only plants but also grapes. From a botanical point of view, it belongs to the ascomycetes. While this fungus can cause considerable damage to market gardening and agriculture, wine production in certain wine-growing regions could hardly do without it.
In autumn, under the effect of morning mist, botrytis gradually develops on the grapes. Its spread is favoured by increasingly dry and warm weather around midday, when the skin of the grapes becomes permeable, leading to the evaporation of the water they contain. Their sugar content gradually increases and their aromas change. Oenologists often refer to a hint of fennel which, combined with fruitiness and sweetness, has a positive influence on the aromatic characteristics of wine made from such grapes.
Other methods used to reduce the water content of grapes and increase the Oechsle degree of the must include harvesting frozen grapes to produce ice wine and drying harvested grapes during the winter in well-ventilated rooms to produce Amarone. However, none of these methods gives the wine the typical fennel aroma of noble rot.