[Vol. 10 



6 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



In 1903 Appel ('03) published a complete account of the po- 

 tato blackleg disease as it occurs in Germany, together with a 

 description of the causal organism. The same investigator (Ap- 

 pel, '05, '06) contributed substantial additions to our knowledge 

 of this disease. 



Butler ('03) mentions a bacterial disease which he thought 

 was possibly the same as that described in the United States by 

 E. F. Smith under the name of brown rot. 



Jones ('05), in an account of disease resistance of potatoes, 

 presented a description of the blackleg disease and accompanied 

 it with observations upon its occurrence in Europe. He re- 

 ported that it was found in Holland, Belgium, Germany, France, 

 and England. The first authentic record of the occurrence of 

 potato blackleg in the United States is that of Jones ('07) who 

 found it in 1906 on a farm in Vermont. The seed used in plant- 

 ing the field came from Maine. He states also: "Vague reports 

 have frequently come to the Station in previous years as to 

 troubles of this class . . ." This author (Jones, '07) "passed 

 almost directly from German fields where it was prevalent, to 

 English fields and found the malady equally common and identi- 

 cal in appearance with that on the continent." This statement 

 is of especial significance in connection with the report of Johnson 

 ('07) who claims to have gathered substantial evidence of the 

 existence of the potato blackleg disease in Ireland. (Compare 

 also with the report made by Pethybridge and Murphy in 1910). 



Harrison ('07) published a very complete account of a potato 

 rot occurring in eastern Canada. The symptoms of the disease 

 described by him were, he states, quite similar to the "Schwarz- 

 beinigkeit" of van Hall and Appel. While he attributes the 

 disease to a bacterial species (Bacillus solanisaprus) new to 

 science, the writer has reason to believe (see below) that the 

 causal agent described by him is identical with Bacillus atrosep- 

 ticus van Hall. Morse ('07) found potatoes affected with black- 

 leg in Maine in 1907. In 1909 he (Morse, '09, '11) published an 

 account of the nature of the disease, its distribution, economic 

 importance, and its control in Maine. 



Smith ('10), however, was the first American to publish a 



full account of 



His description is based 



on studies made with a subculture of Appel's species which he 

 obtained from Aderhold in Berlin, presumably a transfer from 



