140 The Potato 



allowed to dry out for the late main crop of the northern 

 states before planting. All this early tillage also kills 

 many weeds which have formerly been left to be killed 

 by inter-tillage later on. 



After planting there is a period of several weeks when- 

 large and wide tools can be used to advantage in tillage. 

 The harrow, leveler and weeder cover several planted 

 rows at once and kill weeds very cheaply, besides saving 

 moisture. 



The necessity of weed killing for the production of 

 large crops is even greater than the saving of moisture 

 by tillage. Weeds not only rob the potatoes of mois- 

 ture, but are able by their stronger root systems and 

 greater foraging ability to seize upon and use the soluble 

 plant-food in the soil. Very small weeds in this way 

 injure the potato crop more than would be supposed. 

 The weeds which sprout from seeds in the soil are more 

 easily killed before coming up than afterward. The 

 tender shoots from the seeds are killed by a light stirring 

 of the soil which would not affect them at all a few days 

 later. The sprouts starting from the seed have but little 

 vitality until they can reach the surface, and produce 

 green leaves. Then roots start to secure plant-food Avhich 

 is worked by the leaves into material for further growth. 

 Every day now adds to the ability of the young weed to 

 stand punishment and live. Several successive crops of 

 weed seeds can be sprouted and killed by tillage between 

 planting and the time when the potato tops are six inches 

 high. Tillage at this time can be done carefully enough 

 to prevent injury to the growing sprout of the potato 

 before it comes up and until it is established for itself 

 in the soil. Perennial weeds with root stalks, like quack 

 or witch-grass, are much easier controlled by previous 



