Botrytis cinerea is an ascomycete fungus, more commonly known as grey rot when it affects vines in a harmful way. It takes the form of a cottony grey mycelium which colonises plant tissues.

In the vineyard, botrytis has a life cycle that strongly depends on weather conditions. It is particularly virulent during periods of high humidity and mild temperatures, notably in spring during flowering and in late summer or autumn, during véraison and the harvest. The spores of the fungus are dispersed by wind and rain, and penetrate the berries via micro-lesions (caused by insects, impacts, or splitting due to intense rainfall). Once inside, the fungus develops rapidly, leading to the degradation of the berries.

At Château Cazebonne, we observe the possible development of botrytis mainly on the grape bunches. Areas where the leaf canopy is dense or aeration is insufficient are the most conducive to its appearance.

The ecological role of Botrytis cinerea is complex. Although often perceived as a pathogen in agriculture, it is also a decomposer of organic matter in nature, contributing to the nutrient cycle. Its interaction with the vine is mostly harmful, causing significant crop loss and altering the organoleptic quality of the wines. "Grey rot" degrades colour, alters aromas (earthy, mouldy notes) and changes the structure of the wine. However, under certain climatic conditions and for certain grape varieties such as Sémillon, botrytis can develop into "noble rot". This exceptional phenomenon dehydrates the berries, thereby concentrating the sugars and aromas, and is essential for the production of great sweet wines in prestigious appellations. Although our Graves terroir is not specialised in these wines, recognising the duality of this fungus is crucial.

At Cazebonne, our commitment to organic farming requires constant monitoring and a preventive approach to botrytis. We do not use chemical fungicides. Instead, we favour cultural techniques that limit humidity around the bunches. This includes rigorous vine pruning, targeted leaf thinning to improve aeration, and careful management of grass cover between the rows. We are also exploring biocontrol methods to strengthen the resilience of the vine. These practices are part of our overall approach to fostering biodiversity and living soils, reflecting our vision of agroecology in viticulture. We monitor weather conditions closely. We only apply preventive treatments based on copper and sulphur, authorised in organic farming, always sparingly to preserve the balance of our vineyard, in accordance with our sustainable viticulture. Besides botrytis, other cryptogamic diseases such as black rot can affect the vine; careful monitoring is therefore essential.

It is with this same philosophy that Château Cazebonne strives to reintroduce and replant traditional grape varieties in Bordeaux that had almost disappeared. This passionate work of safeguarding our viticultural heritage is made possible thanks to the unwavering support of the many enthusiasts who have adopted our wines and share our vision. To deepen your knowledge, we invite you to receive the digital version of the book "Bordeaux, une histoire de cépages" by Jean-Baptiste Duquesne, to test your knowledge via our oenological quizzes, and to explore our different cuvées by visiting the Cazebonne shop.