JOIMAL OF AIMILTIAL RESEARCH 
Vol. XXVII Washington, D. C., January 26, 1924 No. 4 
THE BLACK-BUNDLE DISEASE OF CORN 
By Charles S. Reddy, Pathologist , and James R. HolbERT, Agronomist, Office of 
Cereal Investigations, Bureau of Plant Industry, United States Department gf Agri¬ 
culture 1 
INTRODUCTION 
As the symptoms produced by organisms known to be parasites 
of com became more clearly differentiated to the writers, there remained 
several groups of disease symptoms for which the explanations were 
meager or lacking. This paper deals with one of these groups of symptoms 
in a general way and specifically assigns an organism, not hitherto shown 
to be a parasite of com, as one of the important causes. 
SYMPTOMS 
Occasionally stripelike lesions are found in the leaves of young, infected 
corn plants (PI. 6, A). Usually,however, black-bundle disease symptoms 
do not become evident during the first half of the growing season. During 
ear development various symptoms may appear as: Leaf and stalk 
color manifestations (PI. i), barren stalks (PI. 2 A, B), nubbin ears (PI. 2 B), 
prolific stalks (PI. 2 C), or excessive suckering (PI. 4 A, B). Such stalks 
usually show blackened fibrovascular bundles (PI. 1). 
In every field of dent, flint, and sweet com ( Zea mays indentata, Z. 
mays indurata , and Z. mays saccharata) under observation by the writers 
it has been noted that a number of plants have become red or purple on 
reaching the dough stage. The red coloration appears first at or near 
the midvein of the topmost leaf and progresses downward on the plant, 
affecting several leaves before progress on the stalk commences. In 
extreme cases the stalks and all the leaves become reddish purple, 
but all gradations between the initial appearance of the red color and 
this extreme condition may be the final color symptoms. Plants having 
any gradation of this reddening or purpling are designated in this paper 
as purple-leaf plants. 
This type of reddening does not conform to any of those described by 
Emerson (14) 2 who says: 
It is of interest to recall in this connection that plant colors of maize—brown no less 
than the red-purple series—develop first in the older parts where growth first ceases, 
such as the lower sheaths and the upper parts of the internodes of the culm. 
However, a type of reddening, indistinguishable from the one en¬ 
countered in commercial fields, sometimes occurs in selfed lines of dent 
com. Inoculation of open fertilized dent corn with a particular organism, 
as will be shown later in this paper, increases the number of purple or red 
plants. 
This disease is characterized also at this stage of development of the 
com plant by high percentages of barren stalks and stalks producing 
1 Accepted for publication Nov. 24,1923. The investigations here reported were conducted in cooperation 
with the Funk Bros. Seed Co., Bloomington, Ill., and the Wisconsin and Illinois Agricultural Experiment 
Stations. • 
3 Reference is made by number (italic) to “ Literature cited, ” p. 203. 
Journal of Agricultural Research, 
Washington, D. C. 
( 177 ) 
Vol. XXVII. No. 4 
Jan. 26, 1924 
Key No. G-356 
73433—24-1 
