A STUDY OF FACTORS INFLUENCING THE YIELD OF POTATOES 1263 



Spraying in Franklin and Clinton Counties 



As previously stated, the late-blight fungus (Phytophthora infeitans) 

 seldom attacks the potato crop in Franklin and Clinton Counties. Very 

 probably the reason for this is that muggy atmospheric conditions, 

 so conducive to the disease, seldom prevail here after rains. On the 

 contrary, wide spacing of plants and the frequent breeze that follows 

 rain afford the plants ideal air circulation, thus preventing conditions 

 favorable to blight. Only 3 per cent of the growers reported blight in 

 1913. 



The extent to which spraying is practiced in this region is shown in table 

 89. Altho the three growers who used fungicide used more than the 



TABLE 89. RELATION OF SPRAYING PRACTICE TO YIELD ON 273 FRANKLIN AND CLINTON 



COUNTY FARMS IN 1913 



average quantity of seed and fertilizer, they obtained less than the average 

 yield. However, no significance can be attached to this fact, because of 

 the extremely small number of farms. For this same reason, no correla- 

 tion study of the frequency of spraying with .the yield in this region has 

 been made. 



RELATION OF DATE OF HARVEST TO YIELD 



The date of harvest of the potato crop is dependent on such factors as 

 (1) the date of maturity of the crop, (2) the date of the first killing frost 

 in the region, (3) the influence of early market prices, (4) the relation of 

 the potato harvest to other farm work, and (5) the weather. The relative 

 importance of each of these factors varies with the region, in New York 

 State. There are sufficient experimental data available to prove that 

 ordinarily the crop should not be harvested until the foliage is entirely 

 dead because of natural maturity. The basis of this proof lies in the fact 

 that the yield is increased rapidly during the last stages of growth of the 

 plant. Jones (1899) tested the influence of the date of harvest on the yield 



