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a widely distributed chemical used against fungous and bacterial diseases of plants.
Bordeaux mixture is prepared on the day of use. One kg of blue vitriol is dissolved in 90 liters (7) of water. While these ingredients are being mixed, 10 1 of freshly prepared milk of lime is added. This causes the precipitation of basic sulfuric salts of copper in the form of a gelatinous precipitate that covers the leaves and fruits of plants effectively.
Bordeaux mixture is used most frequently to prevent grapevine mildew, apple scab, pear scab, and spots on stone fruits. The period and quantity of application depends on the biological characteristics of the cause of the disease and on weather conditions. Plants are sprayed with a 3–5 percent Bordeaux mixture (blue spraying) until the buds open. At the time of vegetation, a 0.5–1 percent solution is used. Bordeaux mixture should not be acidic, or it will burn the leaves. It is slightly poisonous.