214 DISEASES AND ENEMIES OF GROWING PLANTS. 



be made by the plough run 

 ning as near as practicable to 

 each row, after which they 

 F . 40 may be easily thrown out. 



After drying sufficiently, they 



arc ready to be removed to the cellar. Parsnips may be 

 taken up in the same way, or a part of the crop may 

 be left in the ground till they are wanted to use, in 

 spring. 



751. Mangolds should be pulled and stored with as 

 little bruising as possible. The least injury will some 

 times cause them to decay. If properly harvested, this 

 root keeps well till late into spring. 



CHAPTER XXIII. 



DISEASES AND ENEMIES OF GROWING PLANTS. 



752. Disease is the result of deranged vital action. It 

 is brought about both by predisposing and by exciting 

 causes. 



753. Whatever diminishes the natural vigor of the 

 plant, but does not of itself produce a specific form of dis 

 ease, as excessive stimulation, want of proper nourishment, 

 and the propagation of any species for many years without 

 mix ing with other varieties of the same species, or in 

 common Inngusip 1 , not changing the kind of seed planted, 

 is a predisposing cause. 



7-~il. An exciting cause of disease is one which acts 

 suddenly upon the previously debilitated plant, and 



