428 
Journal of Agricultural Research 
Vol. VIII, No. ii 
original descriptions, that the writer soon realized that there was little 
probability of confusing them with the soybean strain, Wollenweber 
(25, 26) and Sherbakoff (20) have described other species and varieties 
of the section Elegans which are not, however, included in this study, 
because they occur on hosts widely separated genetically from the 
soybean 1 and because the authors have not had opportunity to make a 
sufficient number of infection experiments to establish them as wilt 
producers. 
CUI/TURE MEDIA AND THEIR VARIOUS EFFECTS ON SPECIES OF FUSARIUM 
In making a cultural study of these fungi much care was taken to 
follow the suggestions of Appel and Wollenweber (1), Wollenweber (25, 
26), and Sherbakoff (20), in order to determine what criteria to employ in 
judging normal growth characters. It is generally believed that stand¬ 
ardization of cultural methods is highly essential in the comparative 
study of so difficult a group of fungi. 
The writer has kept the soybean and the cowpea strains under con¬ 
stant observation for two years on various kinds of “ natural and artificial 
‘media” and under widely variable physical conditions. He is therefore 
familiar with the possible variability of members of this genus. 
Since a large number of the media used did not prove to be of special 
diagnostic value, they are not discussed here. Among the media most 
commonly employed and serving some particular purpose were oat, 
potato, and string-bean hard agars (3 per cent agar), which, because of 
the paucity of moisture (20, p. 106), give all forms of fruitification with 
“ normal” spores. Five to 10 per cent of dextrose was added to agars 
to favor the production of pigment. Growth on steamed rice in test 
tubes from weighed quantities of rice and measured amounts of water to 
obtain uniformity also results in the formation of pigment and sometimes 
an odor that is typical for certain related species of Fusarium. Herba¬ 
ceous and woody stems, string-bean pods, and potato plugs give the 
best development of sporodochia and pionnotes. 2 Potato plugs also 
serve for the proper development of sclerotia and colors, both of which 
may be reduced or absent from stem plugs when there is a minimum 
development of mycelium. 
According to Wollenweber (25, p. 37), virulence is commonly main¬ 
tained on stem plugs. Living sterile soybean and cowpea seedlings 
grown in 6-inch test tubes were also used and are thought to be a better 
medium for maintaining virulence in the strains from the respective 
hosts. 
1 Wollenweber, H. W. (25, p. 37) says, “The parasite from one host, as a rule, 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.” 
2 For a discussion of these terms, see Wollenweber (25, p. 24, footnote). 
