370 Report of the Mycologist of the 



Potassium ferroej'anide can be pnuchased {it any drug store. 

 The quantity needed for a season's spraying should cost but a 

 few cents. It is a poison. 



Bordeaux mixture must be freshly prepared each time it is 

 needed for use. If alloAved to stand longer than a few hours it 

 begins to deteriorate in value. 



Preparing Stock Solutions of Copper Sulphate and Lime. 



Where large cjuantities of Bordeaux mixture are required it 

 will be found advantageous to prepare stock solutions of copper 

 sulphate and lime. 



Dissolve one hundred pounds of copper sulphate in fifty gallons 

 of water. Each gallon of the solution will contain two pounds 

 of copper sulphate. When it is desired to prepare Bordeaux 

 mixture, three gallons of this stock solution will be sufificient to 

 make a barrel of the mixture. In this way the time consumed in 

 weighing and dissolving the copper sulphate can be saved. The 

 stock solution can be kept any length of time provided it is kept 

 tightly covered to prevent evaporation. 



A stock solution of lime can also be prepared. Lime can be 

 slaked in quantity and kept in a concentrated form if care is 

 taken to keep it covered with water so that it can not harden. 

 When needed for use the required quantity can be taken and 

 diluted to the desired consistency. 



SPRAYING MACHINERY. 



In the spraying experiment reported in this bulletin the Bor- 

 deaux mixture was applied with a knapsack sprayer like the one 

 shown in Fig. 17. The following discussion of knapsack sprayers 

 is copied from Bulletin No. 75 of this Station: 



" Knapsack sprayers, as the name indicates, are machines de- 

 signed to be carried on the back. These are manufactured by a 

 number of firms; the later patterns differ from each other only 

 in small, but occaisionally very essential details. In general, 

 knapsacks consist of a copper tank holding from three to five 



