Plants as Affected by Weeds. 189 



though it is often very difficult to carry out since the 

 suckers of some species grow with great rapidity. Yet, 

 on the whole, no better remedy is known. Frequent 

 plowing and cultivation of the infested ground is usu- 

 ally the most effectual means of preventing leafage. 



Certain very tenacious perennial weeds, as the Can- 

 ada thistle* and the sow thistle,! when growing on 

 deep, rich loams in which the roots spread freely below 

 the plow line, may, it is said, be crowded out by seed- 

 ing the land to grass, at less cost than they can be 

 subdued by the plow. 



If we have mastered the foregoing chapters, we are 

 now prepared to enter upon a more advanced stage of 

 culture, and to learn how to cause new plants to grow, 

 and how to treat the plants thus grown that they may 

 best serve our purpose. 



The following books are recommended for reading 

 in connection with the preceding chapter: Elementary 

 Meteorology, Waldo; Chemistry of the Farm, Waring- 

 ton ; The" Spraying of Plants, Lodeman ; Economic En- 

 tomology, Smith; Fungous Diseases of the Grape and 

 Other Plants, Lamson-Scribner ; American Weeds and 

 Useful Plants, Darlington ; Fungous Diseases of Plants, 

 Duggar. 



» Cnicua arvensis. t Sonchus arvensis. 



