366 Diseases of Truck Crops 



solving one ounce of potassium ferrocyanide in about 

 eight ounces of water. This chemical costs but a few 

 cents in any drug store and will last a long time if 

 kept in a tightly sealed bottle. 



Points to be Remembered 



In preparing Bordeaux the following points should 

 be kept in mind : 



(i) Copper sulphate solutions must be kept only in 

 vessels of wood, fiber, brass, bronze, or copper. They 

 must not be kept in iron or tin vessels, as they will 

 corrode them. 



(2) It is necessary to use fresh stone lime, as air- 

 slaked lime is useless. 



(3) Bordeaux mixture can be used only when 

 freshly mixed. If allowed to stand twelve hours after 

 making, it loses all fungicidal value. 



(4) Bordeaux mixture or lime should never be 

 strained through burlap. The lint of the burlap is 

 likely to work up into the nozzles and clog them. 



(5) Undiluted solutions of copper sulphate or lime 

 should never be mixed together. 



(6) Bordeaux mixture should not be prepared with 

 hot water. 



(b) Ammoniacal Copper Carbonate. The objection 

 to the use of Bordeaux is that it stains the leaves 

 and foliage. 



To avoid staining, colorless ammoniacal copper 

 carbonate may take the place of Bordeaux. It is 

 prepared as follows ; 



