A, FIELD STUDY OF WEEDS 99 



a crop of weeds will deprive the soil of the moisture needed 

 for the useful plants. 



(3) Weeds crowd the cultivated plants and deprive 

 them of sunlight and of space, both in the air and in the 

 soil. 



(4) Weeds growing along fences and ditches afford a 

 good place in which troublesome insects may live over 

 the winter. 



Successful measures in destroying weeds are founded 

 upon a knowledge of the life of the weed and the manner 

 of its propagation. To avoid introducing or spreading weeds 

 is always better than destroying them. It is to be remem- 

 bered, also, that while some weeds may be completely 

 eradicated, others can only be held in check and subdued. 

 While methods must vary for different weeds, a few gen- 

 eral principles are applicable to all. The following methods 

 are effective in keeping weeds in check: 



(1) Prevent all weeds from going to seed and the intro- 

 duction of weed seeds. This will be sufficient to subdue 

 the annuals and biennials. The numerous ways, both 

 natural and artificial, by which seeds may come in, makes 

 it impossible to carry out fully the above rule, but much 

 can be done in this direction that will prove helpful. 



(2) Perennial weeds of all kinds must be cut repeatedly 

 to starve out the underground roots or stems, which in 

 this class of weeds gives rise to a new individual without 

 the production of seeds. If the foliage of a plant is con- 

 stantly destroyed, the death of the plant is only a matter 

 of time and will be caused directly by root starvation. 

 Any breaking or cultivating of the soil in which these 



