Diseases of Plants 295 



Controlling fungous diseases with poison. Poisons 

 which kill fungi are called fungicides. The best-known 

 and most valuable fungicide is Bordeaux mixture. The 

 standard formula for this fungicide is known as the 

 " 4-4-50 formula," so called because it is made from 4 

 pounds of copper sulfate, 4 pounds of fresh slaked lime 

 (or 5 pounds hydrated lime), and 50 gallons of water. 



For the home garden, a smaller amount of the material 

 is usually sufficient for all needs, and it can be made in 

 the same proportions, as follows : 



Prepare separately two stock solutions which we will 

 call A and B. To make solution A, inclose 2 pounds of 

 copper sulfate in a cloth bag, and hang it in a vessel con- 

 taining 2 gallons of water. A metal bucket will be de- 

 stroyed by the solution ; so a wooden or glazed earthen- 

 ware vessel must be used. The bag containing copper 

 sulfate should be hung in the upper part of the water and 

 not allowed to touch the bottom or sides of the vessel. 



To make solution B, prepare a lime paste either by 

 slaking 2 pounds of fresh stone lime in water or by adding 

 2 f pounds of hydrated lime to water. Then add water to 

 make 2 gallons. This solution also must be made and 

 kept in an earthen or wooden vessel. 



These stock solutions may be kept for use throughout 

 the summer, but the vessels should be kept tightly 

 covered to prevent evaporation of water and to keep dust 

 out. As some water will evaporate, it is well to mark the 

 height of the liquid after each use of the stock, and then 

 add water to fill to this height just before the stock is 

 again used. In this way the proper strength of the sojih 

 tion is maintained. 



