With Hail, Downy Mildew Puts the Bordeaux Region Under Pressure

By Audrey Marret

This Terre de Vins article discusses the consequences of hail and downy mildew in the Bordeaux region in 2020. Château Cazebonne, run by Jean-Baptiste Duquesne in Saint-Pierre de Mons (Graves), was particularly hard hit by a hailstorm that affected 75% of its vineyard. This severe weather, occurring after flowering, left the vines vulnerable to downy mildew attacks, a disease favoured by warm and humid weather. The estate, practising organic viticulture, must adapt its treatments to protect its 30 affected hectares out of a total of 42.

The article highlights the difficulties faced by Bordeaux winegrowers in 2020 due to hail and downy mildew. Jean-Baptiste Duquesne, owner of Château Cazebonne in Saint-Pierre de Mons in the Graves, bears witness to the damage sustained by his vineyard. A hailstorm on 4 June damaged 75% of his plots, representing more than 30 hectares of the estate's 42. The half-centimetre hailstones hit 20 to 30% of the berries while the vines were in full fruit set, just after flowering, making any assessment of crop loss uncertain. This situation is compounded by a high risk of downy mildew, encouraged by a very wet spring (more than 900 mm of rain since harvest compared to the usual 500 mm) and warm, humid temperatures. The wounds left by the hail increase the vines' vulnerability to this disease. For Château Cazebonne, which is certified organic, the strategy consists of treating with copper, clay, and sulphur to dry out the environment and promote healing, requiring a 24-hour rain-free weather window.