POTATOES 225 



bordeaux mixture, composed of four pounds 

 of copper sulphate and six pounds of lime to 

 50 gallons of water. This is especially true if 

 the complete vine is covered with this solu- 

 tion. The Colorado potato bettle can be de- 

 stroyed by using three pounds arsenate of 

 lead in this bordeaux mixture. The arsenate 

 of lead is a deadly poison. 



Another reason for spraying is for the 

 purpose of preventing or controlling the po- 

 tato blights. Both the early and the late 

 blight are fungous diseases of the leaf and 

 stalk. The late blight appears usually about 

 the middle of July, and it may be present 

 until the vines are killed in early September. 

 It may be detected by a big brownish spot on 

 the leaf and the peculiar odor about the field. 

 For the treatment of these diseases, use the 

 above mentioned bordeaux mixture. The 

 one mentioned is practically safe without 

 testing, sufficient lime being used to counter- 

 act any burning of the copper sulphate. It 

 will need from 50 to 75 gallons per acre each 

 application, and eight or more sprayings, the 

 more the better as it is almost invariably that 

 frequent spraying increase the yield of po- 

 tatoes per acre besides improving their qual- 

 ity for the table. 



