The Bordeaux mixture was first time used for the control of

The Bordeaux mixture was first time used for the control of Downey mildew of grape vines. Bordeaux mixture is a mixture of copper(II) sulphate (CuSO₄) and quicklime (CaO) used as a fungicide.
It is used in vineyards, fruit farms and gardens to prevent infestations of downy mildew, powdery mildew and other fungi.
It is sprayed on plants as a preventive treatment, but its mode of action is ineffective after a fungus has become established.