Noble rot (; ; ; ) is the beneficial form of a grey
fungus,
Botrytis cinerea, affecting
wine grapes. Infestation by
Botrytis requires moist conditions. If the weather stays wet, the damaging form, "grey rot," can destroy crops of grapes. Grapes typically become infected with
Botrytis when they are ripe. If they are then exposed to drier conditions and become partially raisined this form of infection brought about by the partial drying process is known as noble rot. Grapes when picked at a certain point during infestation can produce particularly fine and concentrated sweet wine. Some of the finest
Botrytized wines are literally picked berry by berry in successive
tries (French for "selections").