86 
Journal of Agricultural Research 
Vol. VIII, No. 3 
many. Delacroix (12) stated in 1906 that he had not seen it in France 
until within two years and that it was not widespread at that time. 
At the same time he pointed out the marked similarity of blackleg to 
the brunissure of the stem previously described by him. The possi¬ 
bility is thus suggested that the malady first described in Germany may 
be* of wider distribution in France than has been reported and that the 
two have been confused. In the same paper Delacroix says that black¬ 
leg exists also in Denmark and Russia. 
In writing of the occurrence of blackleg in England, Jones (19, p. 17) 
stated in 1905 that— 
it is said to be common, though apparently less troublesome than Appel reports 
it from Germany. Reference to the agricultural papers of England during recent 
years indicates that the disease is of quite widespread distribution in that country. 
Harrison (17), in Canada, reports what is probably a much wider terri¬ 
torial distribution of the type of disease he described than was the case 
with the previous writers. He states that he had found it throughout the 
Province of Ontario. Its presence had been reported from Nova Scotia, 
New Brunswick, and Quebec, and one case had been reported from the 
Northwest Territory. 
In the United States the writer has been collecting information regard¬ 
ing its occurrence during the past nine years. It has been reported in 
most and doubtless occurs in all of the Atlantic seaboard States from 
Maine to Texas. It probably occurs also on the Pacific coast, and has 
been recorded from Ohio, Wisconsin, Minnesota, Colorado, Utah, Mon¬ 
tana, and Idaho in the interior. In other words, blackleg has been 
definitely reported from nearly all the great potato-growing centers or 
States in this country. 
There is reason to believe that Maine was one of the first places in 
which the disease was introduced into the United States, and in connec¬ 
tion with the question of geographical distribution it is of interest to 
speculate on how this came about. It seems reasonable to believe that 
it was introduced into Maine from Canada and into the. Dominion from 
England. As will be pointed out in a succeeding section, blackleg is 
carried by seed tubers. Importation of seed stock into Canada from 
England would naturally be much more common than into the United 
States; and the wide distribution of the disease in Canada, reported by 
Harrison, would indicate that it existed there for some time previous 
to its entry into Maine. Maine's greatest potato-producing section, 
where the disease was first discovered, is immediately adjoining the 
Province of New Brunswick. Many of the potato growers in this region 
formerly resided on the other side of the boundary line, and with the 
constant intercourse and traffic between the adjoining sections of the 
two countries it is readily conceivable that blackleg was imported in 
this way. 
