Feb. 17 , 1923 
Parasitic Fungi Internal of Seed Corn 
497 
found principally in the end of the kernels where it feeds upon the starch and produces 
large numbers of spores, mostly microconidia. 
Corn inoculated in the thick milk stage shows the largest percentage of 
infected ears in the field. 
It is worthy of remark that in no case has natural infection by these parasites been 
discovered upon any other part of the immature corn plant save the ears and their 
belongings. Upon the latter infection always begins externally from air distributed 
spores. 
The parasitism of Diplodia zeae has been more thoroughly established 
than any of the other fungi associated with com rots. Heald, Wilcox, 
and Pool (16) state that this fungus produces in the ear a condition 
which may be called ‘ ‘dry rot.” 
In the early stages or in cases of slight attack, no external evidence of the presence 
of the fungus can be detected. It is probable that the hyphae enter the kernel at 
its base, since the fungus is first detected in this region. From this point the hyphae 
grows throughout the kernel and are found in both the endosperm and embryo. 
They consider the prevailing type of infection is through the silk near 
the time of pollination. This disease was observed by Stevens and 
Hall (33) in North Carolina where it is known as “mold,” “mildew,” 
“rot,” and “souring.” 
The disease affects the ear, manifesting itself as a whitish growth of mold over the 
surface of the grains, sometimes affecting the whole ear and at other times portions 
only of it. The amount of fungus visible upon the superficial parts of the grain is not 
large, but upon breaking open the ear, it is found that the spaces between the bases 
of the kernels are often densely packed with masses of pine white mycelium. Extern¬ 
ally, no signs of fruiting bodies of any kind are apparent, but close examination at 
the point of attachment of the grains to the cob, in many instances, reveals the 
presence of exceedingly minute black specs, which under the microscope prove to 
be the fruiting organs (pycnidia) of the fungus. 
They determined the fungus as Diplodia macrospora Earle, but Diplodia 
zeae Lev. also was found in several instances. Smith and Hedges ( 31 ) 
concluded on the basis of pot experiments that the manner of infection 
indicated is the common one, that is— 
from the soil into the roots, from these to the interior of the stems and thence upward 
to the cobs, and finally to the kernels. 
Evans ( 11) reports maize cob mold (Diplodia maydis Sacc.) as prevalent 
in Natal. It is also frequently referred to as mildew. 
Many of the farmers showed me samples of mildewed maize cobs which they stated 
caused them severe loss in their crops, and also produced severe paralysis and fre¬ 
quently death amongst stock that were fed on these cobs, especially if the cobs were 
damp and not properly dried out. 
Van Der Bijl (38) conducted extensive studies on the “Dry-Rot” of 
maize in South Africa and considers that normally infection takes place 
through the silks. A Fusarium is also mentioned as being found several 
times with moldy com. Garman (12) states that— 
Diplodia zeae is not dependent on the openings made by the worm, generally invad¬ 
ing ears by way of the shank. 
Fusarium-like fungi for the greater part were associated with these 
com diseases by the early investigators. It was not until recently that 
several recognized species of Fusarium were definitely established with 
the root, stalk, and ear rots of com. 
Garman (12) along with his studies of pellagra mentions Fusarium and 
Tricothecium roseum associated with moldy com. He states that— 
seed com should be inspected for molds with special care, a pink mold (a Fusarium) 
is very common in our fields and causes many grains apparently sound to assume a 
