CHAPTER XXIV 

 BACTERIAL DISEASES OF PLANTS 



Introduction. Most of the scientific research on the 

 pathogenic bacteria has been done on those species which 

 produce disease conditions in man and animals. Few im- 

 portant investigations of any consequence were made prior 

 to the last decade on the subject of bacterial diseases of plants. 

 Recently bacteriologists have been paying more attention to 

 this subject The United States government has established 

 in the Department of Agriculture a Bureau of Plant Industry. 

 This bureau is actively engaged among other things in mak- 

 ing pathological and physiological investigations of plants. 

 In laboratories in other parts of this country and abroad 

 research is now being carried on along the lines of plant 

 pathology. 



Early Conception. It was held for some time by certain 

 writers, and is still held to a limited extent by some investi- 

 gators (Fischer, Ward), that bacteria do not cause primary 

 infections of plants. The only exception to this condition of 

 affairs, it is held, is in the case of the bacterial nodules which 

 develop on the roots of the leguminous plants. Fischer, for 

 example, in his " Vorlesungen iiber Bakterien " makes the 

 following statements. He calls attention to the anatomy of 

 the plant, and shows that bacteria can only enter through the 



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