39O AGRICULTURAL BACTERIOLOGY. 



This bacillus has been most carefully isolated, cultivated and 

 studied. When used for inoculation it is found to produce 

 the typical disease in the plant. The inoculation experiments 

 are so numerous and definite as to leave no doubt as to the 

 bacterial nature of the disease. 



Brown Rot of Potatoes, Tomatoes and Eggplant. The rot of 

 potatoes is a disease which produces an immense amount of 

 devastation all over potato -raising countries. Not all kinds 

 of the potato rot are caused by bacteria. Some of the widely 

 distributed types are produced by certain species of higher 

 fungi ; indeed, until recently it has been supposed that all 

 potato rots are fungus diseases. Without doubt, however, 

 some forms of this general trouble are bacterial in their 

 origin. The so-called brown rot is widely distributed and pro- 

 duces in some localities a very great loss to the agriculturist. 

 It is characterized by the plants wilting and turning brown, 

 and this is followed by the invasion of the tubers by the dis- 

 ease. The tubers become affected and, in the course of time, 

 more or less decayed in their interior, and perhaps absolutely 

 ruined. The wide distribution of the disease and the great 

 losses which it sometimes involves, make it one of especial 

 interest to agriculture. The cause of this disease has been 

 found to be a bacillus which has been named B. solanaccarum. 

 This bacterium has been isolated, cultivated and used for in- 

 oculation experiments, producing the disease in the plants 

 without fail. 



In addition to these diseases, a few others, which are as yet 

 less thoroughly studied, may be simply mentioned by name. 

 The following diseases are with more or less certainty caused 

 by bacteria : 



The water spot of beans, produced by B. phascolus ; the 

 Bacteriosis of beets, produced by B. bctcz ; the sorghum blight ', 

 producing red and black spots on the leaves of the sorghum 

 and believed to be produced by a bacillus called B. sorghi ; 



