Apr. 38,1933 Species of Fusarium Isolated from Potato Tubers 
357 
individual characters, comparisons were made with descriptions by 
other investigators whenever such descriptions were available. 
SECTION EL^eOANS 
One group (Group D) fell within this section. It included No. 21, 
24, 25, 27, 28, 29, 31, 45, 46, 58, and 59, This was a difficult group to 
identify because of the scarcity of macrospores and the variations 
in color. Microscopically the group (with the exception of No. 59) 
falls into the species Fusarium oxysporum, but no tube culture produced 
sclerotia, which according to Smith and Swingle (jp) were green in 
color and always found in cultures grown on potato plug, and according 
to Sherbakoff {18) were: ' 
Bluish black in color, constantly present on potato tuber plug and sometimes on 
different agars. 
In plate cultures grown on potato agar with 5 per cent of glucose, a 
few of the numbers (21, 28, and 46) produced small, dark purple spots, 
which on examination proved to be masses of nonsporing mycelium; 
but after four weeks of growth these small masses of mycelium seemed 
to be too loose to be called sclerotia. The fact that they did not form 
consistently throughout the group also suggests that they are not the 
sclerotia noted by the authors mentioned above. 
The color of our cultures, also, does not quite agree with fonner 
descriptions of the species. Sherbakoff gives “ macroconidia in mass 
usually of pinkish buff color” but neglects to state on what medium 
this is true. 
On potato-glucose agar plates kept in the light most of our cultures 
(No. 24, 25, 27, 29, 45, 58, and 59) showed salmon coloring varying from 
light buff to ochraceous salmon, but shades of purple are typically found. 
Combinations with pinks and sometimes with greens occur but a greater 
or less amount of purple was characteristic of the group under all condi¬ 
tions. The only media used in common with Smith and Swingle were 
boiled rice and potato tuber plugs. Smith and Swingle found the color 
on the former when grown in the dark “mixed pink and lilac shading 
into white.” Our notes show a production of purple (true) to resolane 
purple. On potato tuber plug these authors noted the growth when 
made in the darkness was “pure white changing to creamy white.” We 
noted a slight development of a pinkish and purple pigment when grown 
in the dark. 
However, these discrepancies in color do not seem sufficient to throw 
these cultures out of Fusarium oxysporum^ but the lack of sclerotia seems 
important We would, therefore, identify these cultures as F. oxy- 
sporum var. ascleroiium,^ a variety described by Sherbakoff which differs 
from F. oxysporum — 
by the absence of sclerotia, and definite plectenchymic sporodochia, in color of the 
mycelium and somewhat longer and narrower macroconidia. 
Sherbakoff neglects to state in what way the color differs. 
Macrospores were very scarce in all the cultures of this group, and in 
No. 24 none at all were found. In the other numbers they varied 
^ It might seem inconsistent after the. discussion on binomial nomenclature on page 355 to make use of 
varietal names in our classification. We recognize the disadvantages of trinomial n<ancnclature but 
feel justified in following it to avoid still further confusion of the names used in this genus. We feel, 
however, that some official recommendations and action should be taken upon the important question 
by societies qualified to represent mycology. 
