LDP_copper_sulphateAs we cycled towards this wall, I thought it was a painting until we got up close and I realised that the blue is due to bouillie bordelaise, a pesticide consisting of copper sulphate, slaked lime and water used to prevent mildew. Mildew was first observed in 1878 on grapevines in the south-west of France. A botanist, Alexis Millardet, accidentally came across the solution a few year later when he noticed that the vines bordering a property in the Medoc in the Bordeaux area were in excellent condition. He learnt that the local wine growers used to spray them with a mixture of copper sulphate and slaked lime to dissuade prowlers from stealing the grapes.

En nous approchant de ce mur en vélo, je pensais qu’il s’agissait d’une peinture murale mais j’ai vu ensuite que le bleu provenait de la bouillie bordelaise, une pesticide composée de sulfate de cuivre, de chaux éteinte et d’eau et utilisée contre le mildiou. On a observé le mildiou pour la première fois en 1878 sur des ceps dans le sud-ouest de la France. Un botaniste, Alexis Millardet, a trouvé par hasard la solution quelques années plus tard lorsqu’il a remarqué que les vignes en bordure d’une propriété dans le Médoc étaient en très bon état. Il a appris que les vignerons du coin avaient l’habitude de les asperger d’un mélange de sulfate de cuivre et de chaux pour dissuader des maraudeurs qui volaient des raisins.

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3 comments on “La bouillie bordelaise

  1. Susan Walter

    That is horrifying — the extent of the stain in your picture and the description of the original use of the stuff. It should be banned. A winemaker friend who no longer uses it said to me once ‘You know, in the 19th century the contents of two South American copper mines were dumped on the Touraine…and it’s still there…’ He no longer uses copper sulphate based fungicides, he uses the phosphate based ones that were developed in the 1970s (which don’t hang around poisoning everything in sight — once they enter the soil they act like a fertilizer). It takes years for the soil to recover from a dose of copper sulphate. Shockingly it is still allowed in organic agriculture — and its use makes a joke of the whole idea of organics.

    BTW, bouillie bordelaise is ‘Bordeaux mix’.

    1. avril Post author

      @William and Susan: I agree that it’s horrifying. I don’t understand why it isn’t banned either. When you see the colour it leaves you can’t imagine wanting it in your system. It didn’t occur to me it might have a translation! I wouldn’t imagine anyone wanting to import the idea! We have slight traces of blue behind the vine at the front of our house so assume it must have been treated at one stage. I didn’t understand what it was at first. The wall was a real eye-opener!

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