142 The Potato 



hot and dry seasons. The loss in yield from tillage at 

 the wrong time, too deep, or too close to the plants, 

 often amounts to a large percentage of the crop. The 

 greatest danger from excessive tillage is likely to come 

 in the northern states in which late cultivation of the 

 main crop comes at the hottest time of simimer. When 

 the "critical period" of the plant's life comes at the 

 time when climatic conditions are most unfavorable to 

 the potato, any injury to the roots is likely greatly to 

 reduce the yield. 



PLANTING 



The time of planting depends on the market for which 

 the crop is grown and the local soil and climate. The 

 higher prices received for extreme earliness in the south- 

 em truck crop compel the use of short-season varieties, 

 like the Triumph and Cobbler, and planting very early 

 to get the crop on the market before prices fall. All 

 cultural methods are arranged with this end in view, so 

 there is little choice in the time of planting. Along the 

 Canadian border and in much of the Rocky Mountain 

 section the whole growing season is but little longer than 

 the life of main-crop varieties. But in most of the prin- 

 cipal growing states, from New England to Iowa and 

 Nebraska, it is possible to vary the time of planting 

 by several weeks. Here, as a rule, most potatoes are 

 now planted in late May and in June. The later plant- 

 ings yield better because the crop matures in cooler 

 weather than with early planting. Moisture is more 

 likely to be abundant in fall than in late summer. The 

 dangers of late planting are late-blight and rot, — unless 

 spraying with bordeaux is practiced, — injury from early 

 frost and early fall freezing of the soil, and conflict of 



