Château Dauzac: Downy Mildew and Bordeaux Mixture

The remedy for downy mildew was discovered serendipitously, in the vineyard of Château Ducru-Beaucaillou, by Pierre-Marie-Alexis Millardet (1838 – 1902), Professor of Botany at Bordeaux University. Millardet and his colleague Planchon were the first to record the presence of the disease in Bordeaux, in 1878. Millardet was a student of Anton de Bary, widely regarded as the father of modern plant pathology, a reputation no doubt engendered by his having proved – using rational, controlled scientific experiment – that a fungus was the cause of the greatest crop disease of all, potato blight. Following Anton de Bary’s lead Millardet duly asserted that downy mildew was also a fungal disease, even though at the time this was still a relatively new concept.

Château Dauzac

Millardet’s discovery was made during an October stroll through the vineyards. He noticed that those vines growing along the roadside in the vineyard of Château Ducru-Beaucaillou, which as noted above was also in the hands of Nathanial Johnston IV, were healthy and lush, whereas those further from the road displayed the usual signs of the disease. On inspection of the healthy plants he noted a strange blue-white deposit painted on the leaves. On locating the domaine’s vineyard manager, Ernest David (1845 – 1932), Millardet learnt that this mix of copper sulphate and lime was David’s favoured method of preventing pilfering of the grapes by passing travellers. It was clear to Millardet, however, that the treatment had a much greater potential. By 1884 both he and Planchon, together with Ernest David, developed from this serendipitous discovery the treatment now widely known as Bordeaux mixture, experimenting not on the vines where it was originally ‘discovered’, but rather on the less precious vines of Château Dauzac.

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