Jan. 26,1924 
The Black-Bundle Disease of Corn 
193 
septate and conform in size to the microconidia of Sheldon’s Fusarium 
moniliforme (47) would differentiate it from C. acremonium. 
ISOLATION OF ORGANISM AND GROWTH ON ARTIFICIAL MEDIA 
The usual method of isolating the organism from the stalks was as 
follows: The stalk, while still turgid, was cut obliquely near the base to 
determine the presence of blackened bundles. If these bundles were 
present, pieces of the internodes were selected, split lengthwise, and 
immediately small portions of the blackened bundles were transferred 
aseptically to potato-agar slants or plates. Many of these gave rise to 
apparently pure cultures of Cephalosporium acremonium and, upon 
abundant sporulation, small pieces of the fungus were used to make 
spore suspensions from which dilution plates were poured. Transfers 
were made from single colonies to potato-agar slants. Internodes 
of the stalks are used because local infections by other organisms 
are somewhat common at the nodes, while organisms causing systemic 
infections are comparatively few in number. Hence, the different 
organisms to be found internally in the internodes are not abundant. 
Cephalosporium acremonium grows on numerous culture media. It 
makes rapid progress on media containing a carbon compound, such as 
dextrose, maltose, lactose, saccharose, mannit, or glycerine. Aerial 
mycelia with conidiophores and conidia usually are present on potato- 
dextrose agar and nutrient-dextrose agar at the end of three days’ growth 
at temperatures between 17 0 and 32 0 C. 
The hyphae in young cultures of recent isolations are in more or less 
loose cottony masses but appear somewhat coarse because of their ten¬ 
dency to agglutinate. The mycelium forms a moderately thick pale 
pink skin on the substrate by anastomosis and agglutination. It does 
not change the color of the agar. When the organism is first isolated it 
is usually pink or salmon colored and spore production is abundant. 
When carried for long periods on artificial media, it soon loses its color 
and more slowly it decreases in spore production and the quantity of 
aerial mycelia. 
Some 3-year old isolations have no aerial mycelia except a few spikes 
of agglutinated hyphae which often form in rosettelike groups. Macro- 
scopically, various isolations show some differences in culture, particu¬ 
larly in the intensity of the pink coloration and in the height and uni¬ 
formity of the hyphae bearing the conidiophores. Isolations from sweet 
com as a rule tend to be pinker in color and the little fascicles of aerial 
hyphae are more irregular and more curled than they are in isolations 
from dent com. The spores are borne singly at the end of the conidio- 
phore and collect in a mucilaginous ball containing from a few to as many 
as 50 or more. The fluid in which they are involved is copious enough 
to obscure any outline of the spores at the periphery of the sphere, giving 
them the appearance of glistening drops. When the spore head is placed 
in water the spores disperse immediately, but each spore retains a cap¬ 
sule. On account of this capsule, measurements of the spores vary with 
the moisture of the medium on which they are grown and with the man¬ 
ner in which they are mounted for examination. In India ink, allowed 
to dry at room temperature and examined immediately, they measure 3-6 
by 1-1.8 microns and average 4.3 by 1.3 microns (PI. 6, B, C, D). These 
measurements apply to isolations from both sweet and dent corn and 
also to the organism supplied by Manns and Adams. 
73433—24-2 
