Bordeaux liquid is a widely used bactericidal plant protection agent on fruit trees. It is a blue colloidal suspension made of copper sulphate and lime milk. It has the advantages of long-lasting efficacy, strong adhesion, resistance to rain erosion, and low cost. It has long played an important role in the prevention and treatment of fruit tree diseases. effect. However, due to its alkaline reaction, the required concentration and dosage of different varieties of fruit trees are also different, and blind use can easily cause phytotoxicity. Therefore, it should be used with caution. Apple Bordeaux mixture is mainly used to control early-stage defoliation and anthracnose in apple. Apple trees are more sensitive to copper and should use a multi- or equivalent Bordeaux mixture. The fruit epidermal cells of red jade, golden crown and other varieties are easily stimulated by Bordeaux mixture and produce fruit rust. These varieties are not easy to use Bordeaux mixture. Pear Bordeaux mixture is mainly used to prevent pears from scab and rust. Pears are more sensitive to copper sulphate and should use a large amount of Bordeaux mixture. Grapes are mainly used to control grapes from black pox, downy mildew and brown spot. Grapes are more sensitive to lime and semi- or equivalent Bordeaux solutions should be used. Fruit trees such as peaches, apricots and plums are particularly sensitive to copper sulphate and cannot be used during the growing season. In addition, Bordeaux mixture should not be used in rainy days, humid air, or dew on fruit leaves to prevent the soluble copper produced by chemical reactions from damaging fruit trees.