Bordeaux mixture is a treatment for fungal plant pathogens invented by French scientist Millardet in the 1880s while he was researching a cure for for downy mildew disease of grape vines in the Bordeaux district of France.
It is still used to this day to treat a variety of fungal plant pathogens.
It is said that he noticed that grapes which had been daubed with a copper sulphate paste to stop passers-by from eating them appeared less affected by downy mildew. This observation led to him experimenting with mixtures of copper sulphate, lime and water and in 1885 Millardet announced to the world that he had found a cure for the downey mildew.
Soaking wheat seeds in copper sulphate solution to prevent seed borne fungal diseases had been standard farming practice in france since the early 1800s