This chemical is called Bordeaux mixture, and its CAS registry number is 8011-63-0. It was invented in the Bordeaux region of France. In France, the use of Bordeaux mixture has also been known as the Millardet-David treatment. This chemical must be used pre-emptively, before the fungal disease has struck. It's harmful to fish, livestock and—due to potential build up of copper in the soil—earthworms.

Preparation of this chemical: Bordeaux mixture can be prepared by different proportions of the components, mainly by the copper sulphate and the lime. Dissolve them separately in water and then mixe them together.