JOURNAL OF AGKCDLTIJRAL RESEARCH 
DEPARTMENT OP AGRICULTURE 
Vol. II Washington, D, C., July 15, 1914 No. 4 
IDENTIFICATION OF SPECIES OF FUSARIUM OCCUR¬ 
RING ON THE SWEET POTATO, IPOMOEA BATATAS 
By H. W. WOLIvENWEBER, 
Pathologist, Cotton and Truck Disease and Sugar-Plant Investigations, 
Bureau of Plant Industry 
INTRODUCTION 
Students of the etiology of diseases caused by Fusarium are often 
handicapped by the fact that they get various results from what appears 
to be the same fungus and obtain like results from apparently different 
fungi. To throw light on the interpretation of such results and to serve 
as a guide for future studies, the group of Fusarium presented in this 
paper may be separated from the remainder of the genus. 
Species of Fusarium play an important part in the diseases of Ipomoea 
batatas Poir., the sweet potato. Many of the 13 different species and 
varieties of this genus of fungi are more or less cosmopolitan and ubiqui¬ 
tous and seem to be harmless to the sweet potato but injurious to other 
plants. Other species, so far as known, are confined to this host and 
connected with serious troubles, such as the wilt disease and the dry-rot 
of the root. Owing to the heavy losses that plant industry suffers from 
these diseases, a thorough investigation was undertaken, in order to 
find methods for their control. This investigation, requiring an exhaus¬ 
tive study of the parasitic fungi, was handicapped by the fact that 
saprophytes are frequently associated with parasites and resemble them 
in certain stages so closely that they are readily mistaken for them. This 
led to contradictory reports as to the nature and causes of the diseases. 
The only way to get uniform results is to base these etiologic studies on 
a monograph of all the fungi associated with the diseases. This paper, 
although not exhaustive, includes at least the most important species of 
Fusarium occurring on the sweet potato. These have been grown in 
pure culture for almost two years until “criteria of the norm and sub- 
(251) 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
Vol. II, No. 4 
July is, 1914 
G—as 
