ENEMIES OF THE SUGAR BEET. 



283 



exist, for plants, like human beings, have their parasites, 

 which in most cases are a consequence of neglect. 



In general cultivation an excess of nitric elements 

 employed in the fertilizers seems to activate the growth 

 of the above. Then, again, the use of manures con- 

 taining invisible insects, which are frequently in great 

 number, is the cause of injury. 



Fig. 74. 



A vertical section of a root attacked by the "brown penetration." 



The sugar beet has no special disease ; those exist- 

 ing are common to other plants. The most important 



