A STUDY OF FACTORS INFLUENCING THE YIELD OF POTATOES 1261 



cient, 0.133 0.065, while positive, is not significant because of the 

 relatively high probable error. Since all factors influencing yield are 

 involved in this correlation, such a coefficient need not detract from the 

 real measure of efficiency of bordeaux spraying. Much of interest regard- 

 ing the actual practice of spraying thruout the region may be observed 

 in the frequency table shown in figure 149. 



Spraying in Steuben County 



The year 1912 was a year of blight epiphytotic in Steuben County, many 

 of the growers reporting more than half their crop left rotted and un- 

 harvested in the field. More than 93 per cent of the growers found that 

 the late-blight fungus affected either tops or tubers, or both. Such con- 

 ditions should afford excellent means for determining the influence of 

 frequency of bordeaux spraying on yield. The practice of spraying in 

 this region in 1912, the average yield, the rate of planting, and the value 

 of manure and fertilizer per acre, are shown in table 87. The two facts 



TABLE 87. RELATION OF FPRAYING PRACTICE TO YIELD ON 360 STEUBEN COUNTY FARMS 



IN 1912 



most clearly set forth in this table are: .(1) that, whereas less than half 

 the growers of this region did any spraying in 1912, only about 4.5 per 

 cent used a fungicide for blight control; and (2) that those growers who 

 sprayed the most thoroly also used more seed and fertilizer per acre than 

 the average, and obtained correspondingly higher yields. 



Spraying in Monroe County 



The treatment accorded the potato crop for blight, tipburn, and flea- 

 beetle control in Monroe County in 1913 is shown in table 88. These 

 data indicate no advantage whatever, as to yield, from fungicidal spraying 

 in 1913. Evidently there was none. The explanation doubtless lies in 

 the fact that the principal functions of bordeaux mixture lie in the protec- 

 tion of the tubers from blight rot and in the prolongation of the plant's 



