11 



dry and fall off, the stalks wither and the crop is consequently 

 ruined or greatly lessened. The best-knbwn remedy at present 

 is to spray the plants with the following: — 



Bordeaux Mixture. 



Copper sulphate (pounds), 4 



Burned lime (pounds), 4 



Water (gallons), 50 



In order to make this mixture easily a stock solution should 

 first be made. This is prepared by placing 20 to 30 pounds of 

 copper sulphate in a cloth bag and suspending it in a wooden 

 barrel containing an equal number of gallons of water. For 

 this purpose a large kerosene barrel, with one head removed, is 

 satisfactory. 



In another barrel slake an equal weight of lime, adding, in 

 all, the same number of gallons of water as was used in the 

 copper sulphate barrel. 



These stock solutions will keep almost indefinitely, and they 

 are a great convenience' when spraying frequently. In pre- 

 paring the Bordeaux mixture for use pour into the spray tank 

 5 gallons of this stock copper sulphate solution and fill the tank 

 about half full of water. Into this pour 5 gallons of the stock 

 of limewater, and then nearly fill the tank with water. In 

 order to learn if enough lime has been added to the Bordeaux 

 mixture to neutralize the acid of the copper sulphate, a test 

 should be made by adding to some of the mixture a few drops 

 of a solution of ferrocyanide of potassium. If a dark precipi- 

 tate appears more limewater is needed, and it should be added 

 until no precipitation results. Having accomplished this the 

 mixture is ready for use in the field. 



The Bordeaux mixture should be applied with a horse-power 

 sprayer equipped to cover five or six rows at once. A pressure 

 of at least 60 to 100 pounds to the square inch should be main- 

 tained, or enough to cause the spray to be deposited as a fine 

 mist. 



In case a regular and thorough spraying is practiced every 

 week to ten days, from the time in June when the potato vines 

 are 6 to 8 inches high until the potatoes are ripe and the vines 



