i88 
Journal of Agricultural Research 
Vol. XXVII, No. 4 
in various ways in single plants. Indications are that certain of these 
symptoms may result from different causative agents and also that all 
of them may be caused by one agent. 
Lack of pollination results in barren plants no matter what the cause, 
and usually all barren plants observed in commercial fields turn purple. 
Corn plants attacked by smut often turn purple and are sometimes 
barren. The physiologic factors accompanying loss of vigor by selfing 
sometimes bring out this color symptom. Other factors disturbing the 
natural physiologic processes of com plants at critical stages in their 
growth may cause purple colorations. For example, one of these may 
be demonstrated by breaking off the ears when in the milk stage. An 
experiment bearing on this was conducted in 1921, the results of which 
are given in Table IX. 
Table IX .—Number and percentage of Yellow Dent corn plants that turned purple 
following removal of ears when in milk stage in comparison with uninjured plants in 
corresponding row, the corn being planted May 27, IQ2I, near Bloomington, III., 
de-eared August 10, and data recorded September g 
Rows. 
Plants. 
Total 
number. 
Purpled. 
Numbep 
Per cent. 
Not de-eared. 
272 
272 
II 
Il8 
4.0 
43-4 
De-eared. 
In the progress of the investigations it has been found that the fungus 
Cephalosporium acremonium Corda (9, p. 11) is one of the most important 
causes in producing the group of symptoms discussed earlier. Occasion¬ 
ally bacteria are found associated with C. acremonium in the infected 
bundles, especially in the lower intemodes. In fact, at first it was sus¬ 
pected that bacteria might play an important part in causing certain 
of these disease manifestations. Even yet, the exact status is not 
fully clear in this respect, but is being investigated further. 
Whether or not the bacteria play a part in the complex, it has been 
found that Cephalosporium acremonium by itself is definitely a parasite 
capable of producing characteristic symptoms, and that it is seed-borne. 
In 1919 special attention was turned to this group of symptoms and 
Cephalosporium acremonium was isolated consistently from blackened 
bundles of purple-leaf plants. Inoculations with this organism at the 
bases of dent, flint, and sweet com when about a foot in height caused 
blackened bundles in the green leaves and in the stalks. From these 
leaves and stalks isolations were made and identified as the organism 
used in the inoculations. Inoculations in the field at Bloomington, Ill., 
and in the greenhouses at the University of Wisconsin and the University 
of Illinois in the following winter proved beyond doubt the pathogenicity 
of this organism; but not until 1921 were any inoculations made with 
pure cultures in the field from which reliable yield data could be secured. 
The methods of inoculation and the results are presented in another 
part of the paper. 
