bouillie bordelaise

Agricultural Uses

Bordeaux mixture is a copper fungicide invented by Millardet of France in 1882. It is a mixture of copper sulphate and lime (either quick lime or hydrated lime), and is available commercially.
Bordeaux mixture is used for the control of numerous plant diseases such as downy and powdery mildews of grapes, scab or fire blight of apple, early and late blight of potato and various leaf spot diseases.
Besides its fungicidal nature, Bordeaux mixture is also used to control bacterial diseases like citrus canker, caused by Xunrhomnus cirri. Bordeux mixture is most effective when used fresh. When stored, it loses its fungicidal property. However, the stability of the mixture can be increased by adding sugar or jaggery at a rate of 0.1 g/liter of water.
A range of formulations has been tried for the preparation of Bordeaux mixture. Of these, the one used often is 4-4-50, representing the respective percentage of copper sulphate, lime and water. For preparing this mixture, solutions of copper sulphate and lime are prepared separately with sufficient quantities of water. They are then simultaneously added to a third container and the mixture is agitated vigorously. The containers should preferably be wooden or earthen or of materials that do not react with copper sulphate.
The advantages of using Bordeaux mixture are that it (a) is cost effective, (b) has natural adhesiveness or tenacity, (c) controls a wide variety of diseases, and (d) is safe to handle. The disadvantages include its (a) phytotoxicity on crops, especially on fruits like apple and peach, (b) corrosive action on metallic containers or equipment, and (c) tendency to delay ripening of the fruit.