2 



BULLETIN" 958^ U. S. DEPARTMENT OF AGRICULTURE. 



with the White Star variety in 1893, harvested at 10-day periods 

 from August 2 to September 22, and with the White Star and Dela- 

 ware varieties in 1898, harvested at the same intervals from August 

 4 to October 6. There was found to be an increase in yield up to the 

 time of the last harvest. A considerable part of the yield of tubers 

 of marketable size developed after the 1st of September. 



Kohler (7, p. 109-111), in experiments with the Early Ohio variety 

 in 1909, by digging tubers at 7-day intervals from July 31 to August 



30 obtained an in- 

 crease in weight at 

 the rate of 7.18 bush- 

 els per acre each day. 

 The gain was also 

 found to be very uni- 

 form throughout the 

 period, with the ex- 

 ception of a slight 

 drop at its end, which 

 was attributed to the 

 loss of foliage as the 

 result of disease. 



Werner (11, p. 20- 

 21) in 1917 found 

 that tubers of the 

 Green Mountain var- 

 riety harvested Aug- 

 ust 10, 20, 30, and 

 September 8 and 11 

 showed daily in- 

 creases of 2.34 bush- 

 els per acre during 

 the first 10-day inter- 

 val, while the in- 

 creases for the last 3- 

 day period were at the 

 rate of 5.27 bushels. 



Wilfarth, Romer, 

 and Wimmer (12) 

 found, in both field and pot experiments with the Geheimrat Theil 

 variety, a fairly constant rate of increase in the weight of tubers 

 during the four periods of growth which were studied. Analyses 

 showed comparatively small changes in the percentages of the min- 

 eral constituents throughout the season, though there was a slight 

 trend toward a decrease until the fourth period, when a very small 

 increase was indicated. 



Experiments conducted in boxes with the Up-to-Date variety, byi 

 Ramsay and Robertson (9), where four harvests were made at inter-' 



Fig. 1. — Plant of the Irish Cobbler variety of potato, showing the 

 tubers borne on short stolons. 



