Fusariiim Blight of the Soy Bean 
41 
SUMMARY 
I. A disease of the soy bean has been studied during the past 
three years. The first report of this disease appeared in a publi- 
cation by the writer in 1917. 
II. The disease is characterized by a chlorosis and shedding 
of the leaves or leaflets, followed by the death of the plants, and 
is herein called 'Tliglit.'’ 
III. Soy bean blight has been observed in several localities 
within Xorth Carolina on soils infested with cowpea wilt. ATiat 
is probably the same disease has been recently observed by others 
in Alabama and possibly in lYisconsin. 
IV. A species of Fusariinn belonging to the section Elegans 
is the causal organism. 
V. Cultural and morphological studies which are regarded 
as of primary importance in distinguishing species of Fusarium 
show that the strain of Fusariinn on soy bean is identical with the 
organism producing the wilt of cowpeas. 
VI. Eeciprocal inoculation experiments with the strains 
from soy beans and cowpeas show that cross-inoculations can be 
made. These experiments were conducted in the greenhouse and 
under field conditions. Pure cultures of the two strains were used 
in certain of the experiments and inoculum from the natural 
host in others. 
VII. Blight of soy beans is therefore due to Fusarium 
tracheiphilum. 
VIII. Physical structure and acidity of the soil under 
natural conditions are not the limiting factors in infection, but 
acidity under certain conditions ma}" have some influence. 
IX. Infection occurs thru the roots, but nematodes appear 
not to increase the percentage of blight materially. Other organ- 
isms such as Rhizoctonia and Sclerotiiim volfsii and other root 
injuries are believed to materially increase the percentage of dis- 
eased plants in the field. 
X. The Black Eyebrow variety of soy beans shows some 
evidence of resistance. The Brown variety, while not resistant, 
is tolerant and seems to develop remarkably in spite of numerous 
fungous filaments and nematodes within the roots. Fifteen other 
varieties tested are severely affected. Velvet beans are not sub- 
ject to infection. 
