Fusariian Blight of the Soy Bean 
IT 
a sterile scalpel and transferred to cooled poured plates of string- 
bean agar (8 c.c. per plate), to each of which four drops of 20 
per cent lactic acid had been added. After several daj's, a micro- 
scopic examination was made of the conidia and mycelium to 
determine whether other organisms were present. Eight trans- 
fers to test-tube slants were made from the margin of several 
plantings and kept for comparison and for indications of con- 
tamination. It may be noted that a large percentage of pure 
cultures was obtained by this method. From the cultures that 
were pure, single-spore cultures were obtained according to the 
method described by Sherbakoff (23, pp. 102-103; p. 104, footnote 
8). Stock cultures were made from these single-spore cultures and 
repeatedly repoured to protect from subsequent contamination. 
Several species of Fnsarium were secured, in order to com- 
pare them with the Fusariurn sp. from the so}^ bean and the one 
from the cowpea, isolated as described above. The following 
species, subcultures from lYollenweber’s authentic cultures, were 
obtained thru the courtesy of Mr. C. W. Carpenter, of the Bureau 
of Plant Industry: Fusarium oxysforuin (Schlecht.), F. vasin- 
fectiirn (Atk.), F. lycopersici Sacc., F. niveiim Smith (members 
of the section Elegans). and F. discolor^ var. sulpliureum 
(Schlecht.) App. and lYollenw. (1, pp. 115-118), (section 
Discolor). 
These species were studied in culture, in order to determine 
their morphological and cultural characters, since such a study 
is considered of primary importance in their differentiation. The 
species mentioned were chosen because all except one belong to the 
section Elegojis^ the section which contains the known wilt-pro- 
ducing species, and because, according to lYollenweber, they are 
the most difficult to separate by this method. F. conglutinans 
lYollenw., F. redolens lYollenw., and F. orthoceras App. and 
lYollenw., of the same section are included in the comparisons. 
They are so different from the others, as indicated by the original 
descriptions, that the writer soon realized that there was little 
probability of confusing them with the soy bean strain. lYollen- 
weber (31. 32) and Sherbakoff (23) have described other species 
and varieties of the section Elegans^ which are not, however, in- 
cluded in this study, because they occur on hosts widely separated 
genetically from the soy bean^ and because the authors have not 
had opportunity to make a sufficient number of infection experi- 
ments to establish them as wilt producers. 
UVollenweber, H. W. (31, p. 37) says, “The parasite from one host has not been 
found on living organs of another host. In pure culture _ the parasite from one host 
did not cause wilt in any other host as a result of inoculation experiments.” 
