EONOMICS OF WEEDS 



61 



(3) Rootstocks )r perennial roots may be starved to 

 death by preventig any development of green leaves or 

 other parts above round. This may be effected by build- 

 ing straw stacks oer small patches, by persistent, thorough 

 cultivation in field by the use of the hoe or spud in waste 

 places, and by saing the plants and turning sheep on in 

 permanent past;; 



(4) The plants nay usually be 

 smothered by dene sod-forming 

 grasses or by a cro like clover or 

 millet that will exlude the light. 



(5) Most rootstcks are readily 

 destroyed by expsing them to 

 the direct action c the sun dur- 

 ing the summer drught, or to the 

 direct action of te frost in the 

 winter. In this \iy plowing, for 

 example, becomeseffective. 



(6) Any cultiv:. on that merely 

 breaks up the Dotstocks and 



leaves them in th ground, especially during wet weather, 

 only multiplies th plant and is worse than useless, unless 

 the cultivation is ontinued so as to prevent the growth 

 above ground. lowing and fitting corn ground in April 

 and May, and cult/ating at intervals until the last of June, 

 then leaving the lad uncultivated during the remainder of 

 the season, is oneof the best methods that could be pur- 

 sued to encourag the growth of couch-grass and many 

 other perennial v?eds. 



Recent studies y Spillman and Gates have shown that 

 the rootstock grases, like quack grass, Bermuda grass, and 

 Johnson grass, anreadily killed out by allowing the fields 

 to become meado\s and pastures, so that a dense sod will 



GOLDEN ROD SEEDHEADS 



