Bordeaux Mixture May 2026

Bordeaux mixture is one of the most historically significant fungicides in agriculture, consisting of a combination of , quicklime (calcium oxide) or slaked lime , and water . First developed in 1882 by French botanist Pierre-Marie-Alexis Millardet to combat downy mildew in vineyards, it remains a staple in both conventional and organic farming due to its efficacy and low cost. Core Components & Chemical Composition

The mixture is traditionally prepared by dissolving copper sulfate in water and adding a suspension of lime. Mixing copper sulfate ( ) and lime ( bordeaux mixture

) results in a gelatinous, sky-blue suspension of copper hydroxide and calcium sulfate. Bordeaux mixture is one of the most historically

The final solution must be neutral or slightly alkaline ( Mixing copper sulfate ( ) and lime (

Two primary methods are used for small-scale and commercial applications:

A common formulation is the 4-4-50 mixture, meaning 4 lbs of copper sulfate and 4 lbs of lime in 50 gallons of water.