[Vol. 10 



2 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Historical 



Frank ('97, '99) was the first to publish accurate and de- 

 tailed descriptions of the potato blackleg disease. One may be 

 assured he was discussing the potato disease which goes by the 

 name of "blackleg" and which is so common and well known in 

 many parts of North America. He reported the cause? of the 

 disease to be a bacterium which he briefly described and named 

 Micrococcus phytophthorus. Micrococci have been frequently 

 met with in isolation plates made from potato steins and tubers 

 affected with the blackleg disease. Many other workers have 

 reported similar experiences, but no one has presented adequate 

 proof that any one of the species of Micrococcus found present 

 under such circumstances is pathogenic to the potato. Until 

 such time as a species of Micrococcus conforming to Frank's de- 

 scription shall be proved capable of infecting potatoes and caus- 

 ing the blackleg disease, Micrococcus phytophthorus Frank 

 should be considered a nomen nudum. 



About 20 years earlier Hallier (78) described an infectious 

 wet rot of the potato and he discussed at considerable length 

 the association of certain bacteria ("Vibrionen," "Bakterien," 

 "Micrococcus") and a fungus (Peronospora infestans Casp.) in 

 the affected potatoes. One cannot determine from the text which 

 of the organisms is of primary significance, but as a mere matter 

 of historic interest it may be noted that this writer contended 

 that the wet rot described by him was caused by "die Produkte 

 der Plastiden der Peronospora infestans Casp." While it ap- 

 pears unlikely that the wet rot described by Hallier is in any 

 way related to the rot due to the blackleg germ, it is nevertheless 

 interesting to note the mention at this early date of a potato 

 tuber rot in which bacteria were found present. 



D'Arbois de Jubainville and Vesque (78), nearly 45 years 

 ago, showed that they were familiar with a potato tuber rot 



("pourriture cellulaire") 



identified 



_y 



but the bacteria 

 disease was thought 



by them to be due to an excess of nutrients and 



A year later Reinke and Berthold (79), as a result of studies 

 of potato decay due to fungi, concluded that a wet rot of potato 

 tubers existed which was not due to fungi. Furthermore, they 

 demonstrated the association of bacteria with the wet rot de- 

 scribed, and they also proved the infectious nature of the rot. 



