EXERCISE XXXIX 



THE STUDY OF BORDEAUX MIXTURE 



Material. Copper sulphate, stone lime, hydrated lime. 



Apparatus. Quart fruit jar, granite kettle, glass stirring-rod. 



Fungicides are chemicals that are used for the prevention or 

 the killing of plant diseases. In some cases, where the fungus, 

 or parasitic growth, is on the outside of the host, the external 

 application of the fungicide will kill the disease. In other cases, 

 where the disease is on the inside of the plant tissue, the host 

 is covered with a fungicide, so that the spores, or reproductive 

 bodies of the disease, are killed before they have a chance to 

 enter the host plant. 



There are several important fungicides. Bordeaux mixture is 

 probably the best-known one, and it is made in different strengths 

 for different purposes. It is a mixture of copper sulphate and 

 lime, and the different strengths depend upon the amount of the 

 chemicals used. The regular standard formulas for commercial 

 spraying are as follows : 



No. 1, STANDARD BORDEAUX No. 2, HALF-STRENGTH BORDEAUX 



MIXTURE MIXTURE 



4 Ib. copper sulphate 2 Ib. copper sulphate 



4 Ib. stone lime 2 Ib. stone lime 



50 gal. water 50 gal. water 



Laboratory formula for standard Bordeaux mixture. Dissolve 

 one ounce of copper sulphate in two pints of water. Place one 

 ounce of stone lime in a vessel, and slake in two pints of water 

 and stir while slaking. Describe fully what takes place. Use 

 these as stock solutions. 



1. Now take one fourth of the copper sulphate solution and 

 dilute it with the same quantity of cold water. Also take one 

 fourth of the lime solution and dilute it with the same quantity 

 of cold water. Pour the two diluted solutions together, fill a 

 quart jar, and label. Describe what takes place and give the 

 color of the solution. 



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