16 Mar 2023

Botrytis cinerea is a fungus that can affect grapes and other parts of the vine in humid conditions.  The names comes from the Greek botrys ('grape') and Latin cinerea ('ash-like', from the grey appearance of the affected grapes).  It can live through the winter as mycelium or sclerotium within dormant buds, vine bark or on plant debris on the ground.  Grapes typically become infected with Botrytis late in the season, during the sugar accumulation phase, i.e. when they are ripe.  

The more common expression of botrytis is as devastating gray rot (“pourriture gris”), a common malady of the vine, experienced in many regions.  However, in some areas, in the right conditions, a desirable botrytis infection occurs, producing what is called noble rot (“pourriture noble”).  Regions producing sweet wines influenced by botrytis cinerea include Tokaj from Hungary, Sauternes and Trockenbeerenauslese from Germany.  

A classic botrytis year might proceed on the following lines:  Humid weather in July, as the grapes are beginning to accumulate sugars, followed by hot, dry weather, shrivelling the grapes and producing a raisin-effect; followed by autumn mists, which encourage the botrytis to bloom and develop slowly.  

The mould dehydrates the grapes, leaving them shrivelled and raisin-like, and concentrates the sugars in the process, turning them from simple into complex sugars, which develop a huge range of flavours with time in bottle.  The result is a sweet wine with deep, honey-like luscious flavors.  Some of the classic aromas of developed botrytised wines are ginger, honey, beeswax and elastoplast!

A microscopic view of the filaments of botrytis cinerea mould that penetrate the grape skin, drawing out moisture and converting simple sugars into complex sugars in the process

The terroir in Sauternes is particularly suited to this process, with the Garonne and Ciron rivers producing mists in the morning, which then burn off in the warm afternoon autumn sunshine, a scene that always reminds us of Keats’ line about the “season of mellow fruitfulness”.  No other wine we can think of is able to capture more perfectly the weather of a particular year and to express it many decades later.  Currently we have some bottles of 1893 Yquem on our list that, 130 years on, still show signs of the rain and mist which affected Sauternes in October of that year.

Because the amount of juice extracted from these grapes is extremely low, it takes a lot of vines to produce a small amount of wine.  Yields in Sauternes, for instance, are often around 8-15 hectolitres per hectare (compared with 35-45 hl/ha for comparable red Bordeaux estates).

Below, you will find some of the Sauternes from our list.