Feb. 17, 1933 
Parasitic Fungi Internal of Seed Corn 
52i 
cular infection through the butt. Even after maturity if the corn is 
exposed to excessive or constant moisture, the various parasites as well 
as saprophytes may be established in the storage tissue of the fruit. 
This we believe in part explains the presence of AspergUlusniger and 
Penicillium spp. that frequently appear even after thorough disinfec¬ 
tion. They have become established because of unfavorable conditions 
under which the corn has been exposed and stored. These types of 
fungi on the germinator may also retard or in some cases inhibit germina¬ 
tion. They attack the storage tissue of the scutellum in a way similar to 
Rhizopus nigricans , as described by Adams and Russell (2). It is noted 
that where extensive rotting of kernels occurs on ears it is usually con¬ 
fined to the upper end. The exception in the case of the F. tnonUiforme 
kernel-rot is difficult to explain. The irregular rotted kernels, as shown 
in Plate 12, E, may have been individual grains delayed in ripening or 
ones for some unknown reason susceptible to infection. It is still an 
open question as to the possibility of direct silk infection. 
Second: Indirect seed infection by means of systemic, stalk or shank 
infection. Smith and Hedges (ji) have advanced some evidence of 
systemic infection for Diplodia zeae. If such type of infection commonly 
occurs with these parasites it would seem reasonable to expect poorer 
stands of corn than are reported. There is no doubt that a systemic 
infection occurs, but how commonly remains to be determined. Such 
infection does not necessarily have to follow from the planting of infected 
seed but may also occur because of soil infestation. Regardless of root 
infection, the stalk or shank may become points of initial infection. 
The fungus may in this way follow the vascular tissue into the fruit. 
This may be the most common means of infection and may explain the 
internal infection in seeds showing no external symptoms. Hoffer and 
Holbert {18) state that— 
after the first killing frost the stalks and especially the shanks and the ears are invaded 
rapidly by these disease organisms. Warm weather following the first killing frost 
favors those ear infections, which greatly reduce the vitality of the seed. 
A discolored or “stringy” condition of the butt is very suggestive of 
vascular infection. An extensive survey has failed to consistently cor¬ 
relate a discolored butt with infection of kernels. A discoloration of 
the butt may occur subsequent to harvesting as the result of poor storage 
conditions and many types of black molds found established. When 
the ear is broken in half and a discoloration of the vascular system is 
observed, it is very good evidence of an infected ear. The growing point 
consisting of the preformed nodes may be some distance beyond the 
foci of infection. After mature growth in height is readied the infec¬ 
tion may spread so as to become systemic and penetrate the ears. Inoc¬ 
ulations under field conditions should easily establish this point. 
The pathogenicity of the four parasites discussed has been definitely 
established under greenhouse conditions. Oyer 1,500 plants have been 
grown to determine seedling infection and for inoculation work. It is 
planned to duplicate much of the inoculation work under field condi¬ 
tions. Nodal and internodal inoculations have indicated the rapid 
internal development of these parasites. The importance of each of 
these parasites requires much more study along lines of inoculation and 
the activity of the fungus. 
Severe internal infection of plants even in the tassel stage has not 
caused any pronounced external symptoms. The com plant, because 
