1158 



EARLE V. HARDENBURG 



FlQ. 131. GROWTH VARIATION BETWEEN NEW AND ONE-YEAR-OLD MAINE SEED STOCK ON 



LONG ISLAND 

 The photograph shows also the characteristic topography of potato lands in Suffolk County 



Valuable studies of the influence of weather on the yield of potatoes 

 in Ohio for a period of fifty-five years have been made by Smith (1915), 

 and a similar study for a period of twenty-six years has been made in 

 New York by Fox (1916). The relationship of both growing-season 

 rainfall and temperature, in both States, is expressed in terms of the 

 coefficient of correlation (r). A comparison of these coefficients shows 

 that July is by far the most critical month with respect to these factors, 

 in both Ohio and New York. The coefficient of correlation between tem- 

 perature and yield is in most cases negative for both States, indicating 

 that yield is inversely proportional to increase in temperature. So far 

 as rainfall is concerned, the correlation for Ohio is positive and fairly 

 large, indicating that rainfall is ordinarily a limiting factor in yield. The 

 correlation of rainfall and yield in New York, on the other hand, is negative, 

 showing that years of high rainfall are years of low yield. The average 

 growing-season rainfall for the potato sections of New York, previously 

 given as ranging from 14 to 20 inches, is evidently sufficient for this crop. 

 The negative coefficient of correlation is probably a reflection of the fact 

 that years of highest rainfall in New York have been years of severe loss 

 from blight rot. 



