Bacteria in their Relation to Vegetable Tissue. 35 



APPENDIX GIVING A LIST OF THE BACTERIAL PLANT DISEASES, 

 WITH BRIEF KESUME OF THEIR PRINCIPAL CHARACTERISTICS. 



The preparation of a complete abstract of the bacterial diseases of 

 plants at present is attended with some difficulty. Besides the num- 

 ber of well authenticated and confirmed observations upon this class 

 of diseases, there are quite a number of maladies which have been as 

 yet incompletely worked out. The disease has been experimentally 

 reproduced only by inoculation of diseased tissue, not by infection 

 from a pure culture of the germ. The classic canons of Koch, which 

 are regarded as essential in the elucidation of the etiology of an 

 animal disease, are, however, just as applicable in the investigation 

 of plant maladies, and we can consider no disease as sufficiently 

 proven to be of bacterial origin until the germ has first been isolated, 

 and then successful inoculation experiments made with the pure 

 culture of the organism. 



The literature embracing this branch of phytopathology is largely 

 American, but it is widely scattered, and it was thought that a brief 

 resume of the bacterial plant-diseases known to date would be of 

 value. So far as I am aware, this has not yet been attempted in any 

 complete degree. Gomes' Crittogamia Agraria (Naples, 1891) and 

 Ludwig's Lehrbuch der Niederen Kryptogamen (Stuttgart, 1892) 

 are the only works from a European source that attempt to deal in 

 any satisfactory way with the bacterial plant-diseases, and even these 

 include only a part of the diseases already known. 



Tables I and II give a list of those diseases which have been traced 

 to a bacterial origin and where the disease is claimed to have been 

 experimentally produced by inoculation of pure cultures. Table III 

 gives a provisional list of diseases possibly of bacterial origin, but 

 the etiology of each malady has not yet been traced to a specific 

 microbe, and consequently cannot be regarded as thoroughly proven. 



The number of plant maladies caused by bacteria might have been 

 considerably increased if all the cases on record of the presence of 

 bacteria in diseased tissue had been added. This, however, does not 

 signify that the bacteria bear any etiological relation to the disease, 

 and it is possible that in many of these cases they are present only 

 as decomposition-organisms in dead or dying tissue. A considerable 

 number, however, of these have been added, as it has been suggested 

 that it might be useful to collect the data on this subject, imperfect 

 or otherwise, which at present are so , widely scattered in various 

 publications. 



