With the progress of pathological studies, other diseases were 
recognized in the United States, some of which, like the southern 
bacterial wilt or brown-rot (Smith, Erwin F., 1896), had doubtless 
been long prevalent, if not actually endemic, in the United States, 
while others, like the blackleg (Bacillus pTiytophthorus Appel and 
related forms), appear to have been recently introduced into this 
country from Europe. 
APPEARANCE OF NEW TROUBLES. 
About 1904 there began to come into prominence a group of potato 
diseases hitherto not generally recognized as of economic importance. 
In that year there was published by Smith and Swingle a bulletin 
which described a wilt and dry rot due to Fusarium oxysjporum, 
found in the District of Columbia, Michigan, and elsewhere. This 
was the first important work of the sort in the United States, though 
a disease that was very likely the same Fusarium wilt was mentioned 
by Clinton in 1895 as "bundle blackening of tubers." No mention 
was made of its relation to any disease of the plants, and it was con- 
sidered "not a very serious malady." The cause was said to be a 
fungus "quite similar to" the one causing dry end-rot. 
The disease described by Stewart (1896), and thought by Smith 
and Swingle to be probably the same, was stated by Prof. Stewart 
at a recent meeting of the American Phytopathological Society to 
be not due to a Fusarium. 
In the year 1905 there occurred in Europe an outbreak of a disease 
which was named leaf -roll (Blattrollkrankheit). This recurred in 
1907 with such virulence as to excite general alarm, and the attention 
of many pathologists and other agricultural workers was directed 
toward its study and prevention. Leaf-roll has continued to cause 
heavy losses in Germany, Austria, and elsewhere, though it has not 
become as generally destructive as was feared. Its nature remains 
a subject for debate. In the early years its resemblance to the 
American disease described by Smith and Swingle led to the general 
adoption of the theory that it was due to or associated with a Fusa- 
rium. The evidence on this point was very contradictory, and 
there have developed nearly as many opinions as there are investi- 
gators. 
In America little was done after the work of Smith and Swingle 
until 1908, when an outbreak in an important potato district in 
California was studied by the present writer and found to be the 
same Fusarium wilt (Orton, 1909). 
The writer continued his survey of the country in 1909 and 1910, 
finding the Fusarium wilt very widespread. In 1911 he studied 
potato diseases in Europe with the particular purpose of comparing 
the American Fusarium wilt with the European leaf -roll disease, 
