Noble Rot

Noble rot not an attractive phrase but, as with most things, it sounds much better in Italian, muffa nobile. Either way, it is a beneficial form of fungus that can infect the (usually) overripe grapes during damp conditions. If the weather then turns drier the fungus takes water from the grape thus raising the solids and sugar content and the result is a sweet dessert wine. If the damp conditions persist the grapes are lost and therefore there is no wine.