82 
Journal of Agricultural Research 
Voi. vm. No. 3 
nomic importance there. He regarded the causal organism as a new and 
distinct species to which he gave the name “Bacillus solanisaprus.” 
His study was the most detailed and complete of any which had 
appeared up to this time upon an organism associated with blackleg. 
The writer came to Maine in 1906, too late in the season to find the 
disease that year, but in 1907 it was found and its presence recorded (22). 
Preliminary accounts regarding the nature of the disease, economic 
importance, distribution, manner of dissemination, and means of control 
were published in 1909 (23) and 1911 (24). 
In 1911 Pethybridge and Murphy (26) published a review of the litera¬ 
ture on the subject and described a similar type of disease in Ireland. 
These workers also considered the organism responsible for the type of 
malady there to possess sufficient distinctive characters to be considered 
a separate species, although they felt that it was closely related to 
j Bacillus phytophthorus. They named it “ Bacillus melanogenes” 
CHARACTER AND APPEARANCE OF THE DISEASE 
Blackleg is, as has already been indicated in the preceding section, a 
bacterial disease of the stem and tuber of the potato. The various com¬ 
mon names which have been applied to it have been given largely as a 
result of the quite characteristic signs of the disease which are exhibited 
by the attacked stems.. In Germany, where the trouble was first described, 
it has been known for years as Schwarzbeinigkeit , although the term 
“ Slengelfaule” has also been applied to it. It would seem from the 
literature that the former name or a somewhat free translation of it is 
the one which has been in common use in Holland, Belgium, France, 
and England. Jones (19, 20) described it under the name “blackleg/' the 
name with which he had become familiar in England and Germany. 
Smith (33) prefers “basal stemrot.” Pethybridge and Murphy (26, 
p. 9-10) state that— 
Since, however, the term “Blackleg” is one which is already in common use in 
this country for a disease prevalent among cattle, it seems strongly advisable, in 
order to avoid confusion, not to use the term “blackleg” for the present disease; and 
we have, therefore, decided to distinguish it by the name of “Black Stalk-rot.” 
Were the writer describing this type of disease for the first time, he 
would endeavor to select a somewhat more appropriate name than black¬ 
leg and would prefer black stalkrot or black stemrot to this. However, 
he has found the objections to the former term to be of more theoretical 
than real importance. 
Blackleg, as the name indicates, is characterized in its typical form by 
a pronounced blackening of the base of the stem of the affected plant. 
However, such plants frequently show other visible signs of disease 
before this character is apparent above ground. They first appear more 
or less unthrifty and usually undersized. The branches and leaves, 
