WEEDS AND THEIR CONTROL 



491 



sufficient time to kill the root or other propagative parts. 

 In this direction, much may be accomplished through 

 change in the rotation and in cutting the weeds at the 

 proper time. But much may be accomplished by tillage. 

 This may be largely accomplished in tillage for other 

 purposes. Some of the practices which aid the process 

 are: 



(1) Early and frequent tillage. Weeds are most 

 easily killed when young. Soon after the seed has ger- 

 minated, they are most delicate. Stirring the soil at this 

 period may so change their relation to it as to cause 



Fig. 150. Erosion on a gravelly hillside. 



