208 



Diseases of Economic Plants 



Soft-rot -'''' (Bacillus carotovorus) . — This soft-rot, first 

 noted in New York in 1898, is a common cause of loss of 

 onions. In many fields, one-third to one-half of the crop is 



Fig. 111. — Botrytis sclerotia at necks of bulbs. 

 After Munn. 



destroyed, and the balance of the crop injured by the pres- 

 ence of the rot. 



Frequently a single leaf scale of an otherwise sound onion 

 is entirely rotten, or again several scales may be rotted. If 

 the outer scale is rotted, the bulbs are designated by the 

 growers as "slippery onions." The rot does not spread from 



