Bordeaux Mixture

Aiton's Encyclopedia (1910)

Important: Safety Warning This page recommends pest-control substances such as arsenic compounds, strychnine, or cyanide — in some cases applied to food crops. These substances are lethal to humans and animals, and their use is now banned or strictly controlled. This information has been left in for historical purposes but should not be acted upon. a liquid much used for spraying plants. The name is due to the early use of the mixture by members of the Academy of Science at Bordeaux, France. It was found about 1880 that copper sulphate, or blue vitriol, had the virtue of killing mildew and other parasitic growths on grape-vines. The use of the mixture spread from the grape growers of France to Germany, Spain, Italy, England, and other countries, both of the Old World and the New, until Bordeaux mixture has come into general use among florists, fruit growers, and gardeners as a preventive of mildews, rusts, scabs, etc. Growers of peaches spray before the buds open to kill all spores. Potato growers spray their vines to keep the leaves from rusting. The mixture is a general remedy for the fungous plant pests that infest the garden and orchard, just as paris green is the foe of corresponding insect pests. Although the use of the mixture is recent, farmers' clubs and granges, as well as large growers of potatoes, now order blue vitriol by the car load. One writer recommends the following method of preparing the mixture: Blue vitriol dissolved in water, warm, even hot water is best, 6 pounds; slaked lime dissolved in water and strained, 3 1/2 pounds; water, 50 gallons. Shake thoroughly. The mixture may be applied wastefully with a whisk broom or a watering pot, but the proper way is to use some sort of a syringe or force pump provided with a spraying nozzle. See Spraying ; Paris Green 2026 Editor's Note: Bordeaux mixture is still sprayed today, well over a century on, and holds a curious position: as a simple copper-and-lime preparation it is one of the few fungicides permitted in organic farming. Its drawback is now clear too — copper does not break down, and decades of spraying have left it accumulating in old vineyard soils. (Ed: BR 2026-07-03)