CORN ROOTROT STUDIES 1 
By Thomas F. Manns, Plant Pathologist and Soil Bacteriologist, and Claude E. 
Phillips, Delaware Agricultural Experiment Station 2 
During the past few years a great deal of study has been devoted to 
the com rootrot disease. Most of the investigators agree more or less 
on the symptoms manifested by it, but there seem to be differences of 
opinion as to the relative importance of the organisms causing it. The 
report which follows presents the results of investigations made to 
determine the importance of the various causal organisms. Time limi¬ 
tations made it necessary to conduct all of the infection work under 
laboratory and greenhouse conditions. 
HISTORICAL REVIEW 
A review of the literature covers investigations pertaining to corn 
rootrot in so far as the writers have been able to secure them. In this 
review special mention is made only of results which bear directly on 
the importance of the causal organisms. 
Saccardo (jj, p. 14) 3 reported Oospora verticilbides in Zeae maydis 
in 1886. It is now quite certain that this fungus is identical with Sheldon's 
( 13) Fusarium moniliforme. Burrill and Barrett (2) in 1909, investi¬ 
gating the earrots of com, reported that—■ 
the active agents of destruction are several species of parasitic fungi, among which 
one does by far the most damage, probably 90 per cent of the whole amount. This 
is known botanically as Diplodia zeae (Schw.) Lev. * * * At least three other 
species of fungi all belonging to the genus Fusarium attack, with somewhat similar 
results, the developing ears of com. 
Heald, Wilcox and Pool (7) in 1909 stated that— 
Diplodia zeae produces in the ear a condition which may be called “ dry rot, * ’ though 
probably the majority of com growers refer to such ears as molded. 
Stevens and Hall (15) in 1909 also reported that they found Dipbdia 
zeae in North Carolina where the disease is known as “ mold, ” “ mildew,” 
“rot,” and “souring.” Arzberger (r) in 1913, working upon cobrot of 
com, stated that— 
Coniosporium has an economic significance in that it destroys the cob tissue as a 
saprophyte; its effect on the kernels is rather limited when compared with the injury 
of Diplodia, Fusarium and other fungi. 
Hoffer and Holbert (8) in 1918, found that— 
the same organism which causes scab of wheat also causes rot of the stalks, ears and 
ear-shanks of com plants. 
Valleau (17) in 1920, reported that— 
Fusarium moniliforme is an active parasite and is capable of causing root and stalk 
rots of com under laboratory and field conditions. Inoculation experiments with 
1 Received for publication Nov. 21, 1923. 
* The major part of this investigation was made by the junior author in preparation for a minor thesis in 
graduate work in plant pathology at the University of Delaware. 
* Reference is made by number (italic) to “ literature cited, ” p. 964. 
Journal of Agricultural Research, 
Washington, D. C. 
(957) 
VoL XXVII, No. m 
M ar. aa, 1934 
Key No. Del .-5 
