A STUDY OF FACTORS INFLUENCING THE YIELD OF POTATOES 1259 



their crops affected with blight, while nearly one-fourth reported flea- 

 beetle injury. The spraying practices and the average yields, together 

 with the amount of seed and the value of the fertilizer used, are given 

 in table 84. The number of growers not spraying at all was too small 



TABLE 84. 



RELATION OF SPRAYING PRACTICE TO YIELD ON 316 LONG ISLAND FARMS IN 

 1912 



to allow of attaching any significance to the average yield obtained by 

 these growers. The increase in yield per acre of over 35 bushels, resulting 

 from the use of a fungicide rather than an insecticide, is significant, altho a 

 part of this difference in yield was due to the use of more seed and fertilizer. 

 Results of further studies on the influence of frequency of spraying with 

 fungicide, on yield, are shown in tables 85 and 86, in which the factors of seed 



TABLE 85. 



RELATION OF NUMBER OF TIMES SPRAYED WITH FUNGICIDE, AND RATE OF 

 PLANTING, TO YIELD, ON 109 LONG ISLAND FARMS IN 1912 



Amount of seed planted' 



