JOURNAL OF AGRICULTURAL RESEARCH 
DEPARTMENT OF AGRICULTURE 
Vol. VII Washington, D. C., October 30, 1916 No. 5 
SPONGOSPORA SUBTERRANEA AND PHOMA TUBEROSA 
ON THE IRISH POTATO 
By I. E. MelhuS, Pathologist, J. Rosenbaum, Mycologist, and E. S. Schultz, Expert , 
Cotton and Truck Disease Investigations, Bureau of Plant Industry 
INTRODUCTION 
After finding that Spongospora subterranea was well established within 
our borders, the writers undertook to learn what its effect might be on 
the American potato (Solanum tuberosum) industry, taking up for this 
purpose the study of such questions as its geographical distribution and 
the factors governing the same, relation of the fungus to the roots and 
stems of the plant, and the possibility of its occurrence on other hosts. 
Such points as its damage to the tubers, relation to soil types, moisture, 
and control measures have received consideration. Some of these points 
have not been fully settled, but the data available are published here 
because of the widespread interest in this disease and its importance in 
many parts of the United States. 
GEOGRAPHICAL DISTRIBUTION OF SPONGOSPORA SUBTERRANEA IN 
THE UNITED STATES • 
When Spongospora subterranea was discovered in Canada and in Maine, 
the question as to what would be its distribution in the United States 
immediately arose. Although quite extensive, European literature 
regarding the disease caused by this fungus contains but little informa¬ 
tion as to the factors that determine its geographical distribution. Owing 
to this fact and to the varied soil and climatic conditions in the United 
States, the writers were confronted with a new problem, which has been 
studied by means of surveys, by planting infected seed in many different 
localities, and by transplanting soil from various Southern States into 
the infected section of northern Maine. 
DISTRIBUTION AS DETERMINED BY SURVEYS 
Since the publication in the spring of 1914 of Bulletin 82 of the Depart¬ 
ment of Agriculture (8) 1 , which showed that the disease was then known to 
1 Reference is made by number to “ Literature cited,” p. 253. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
ft 
(213) 
Vol. vn, No. S 
Oct. 30,1916 
G—96 
