CROP ENEMIES AND FRIENDS 



195 



are borne in different places on the same plant. It infests culti- 

 vated fields, and often 

 grows as thick in grain 

 stubble as if it had been 

 sowed there. 



Ragweed can be de- 

 stroyed by late cultivation 

 in hoed crops, and by 

 plowing grain land and 

 sowing on it such crops as 

 cowpeas or clover. Stray 

 ragweed plants along 

 fences and streams should 

 be cut down before they 

 scatter abroad their hosts 

 of seeds. 



How to destroy Annuals. 

 Most annuals are easily 

 destroyed by clean culti- 

 vation of crops, especially 

 by late cultivation. As 

 far as possible, seeding 

 should be prevented. The 

 plants should be mowed 

 before they flower, or 

 burned before the seed 

 mature. . 



Biennials. Among our 

 most troublesome biennial 

 weeds are the bull or pas- 

 ture thistle, burdock or great deck, and wild carrot. None 



FOUR COMMON WEEDS 



amaranth ; b, crab grass ; c t ragweed ; d, pigeon 

 grass 



