Correct Option: B

Downy mildew of grapes disesase is linked to the discovery of Bordeux mixture as a popular fungicide. Bordeux mixture was discovered by Millardet in France in 1882. Bordeux mixture is prepared by dissolving 40g of copper sulphate and 40 g of calcium hydroxide in 5 litres of water. Bordeux mixture is used primarily as a fungicide, it was first used to control downy mildew disease of grape-vine caused by a fungus, Plasmopara viticola. The first pesticide to be used commercially was bordeux mixture.