706 
Journal of Agricultural Research 
Vol. XXXI, No. 8 
DISTRIBUTION ON MAIZE 
In this connection, it may not be amiss to consider some passages 
in the writings of several investigators working on leaf blight in 
tropical or subtropical regions, which can scarcely be regarded as 
aptly descriptive of Helminthosporium turcicum . Reinking (10), 
working in the Philippines, described the conidia of H. inconspicuum 
C. and E. (~H. turcicum Pass.) as “large, septate, curved brown/' 
a characterization that in regard to coloration and curvature is not 
generally appropriate. Two figures—one (10, jig . Ifi B) represent¬ 
ing a conicuum from a maize tassel, the other (10, jig. 40 , tower c) 
representing a conidium from a maize leaf—especially deserve 
comment. The former is shown as a slightly curved structure with 
nine cross-walls, diminishing only slightly toward the abruptly 
rounded end, and, from calculations of the size of the figure and the 
scale of magnification, measuring approximately 112 /x in length 
and 17 /x in diameter; the latter is more strongly curved, provided 
with 10 septa, tapering somewhat more strongly toward the rounded 
ends, and measuring approximately 128 /x in length by 17 /x in 
diameter. The spores would appear to be too slender relative to 
their length, too abundantly septate, and not tapering toward the 
ends sufficiently to be typical of the leaf-blight fungus. Of the 
other figures given by the same author, 41 b would evidently seem to 
represent conidia of H. turcicum, while 40 upper c as well as 4$ appear 
to pertain to this species, though with less certainty. And the nabit 
figure undoubtedly represents the extensive foliar lesions character¬ 
istic of leaf blight. 
The descriptive passages in Marquez' recent paper (7) on leaf 
blight of corn, incorporating the results of studies carried out at 
Los Banos, are not free of the same sort of ambiguity. 
Since the lesions of both leaf blight and leafspot are elongated in a 
longitudinal direction and are apt to coalesce, the description of the 
earlier stages may have been drawn from specimens representing 
either type or probably both types of infection. The leafspot 
lesion with its parallel lateral boundaries coinciding with two consec¬ 
utive veins of the host are more accurately described as “stripes" 
than the effuse areas killed by leaf blight. They also coalesce with 
much greater frequency, indeed not attaining any considerable size 
unless abundant coalescence takes place, since the greatest individual 
lesions rarely exceed 3.0 mm. in width and 15.0 mm. in length. The 
leaf blight lesions on the other hand, become relatively very exten¬ 
sive without any coalescence whatever. It is not improbable that the 
description of the old spots refers to the latter type of lesion, since 
fructifications of Helminthosporium turcicum are always visible as a 
grayish efflorescence in the central portion of large affected regions. 
In the material from both Florida and the Philippines as obtained 
from the field, the fructifications on the leafspot lesions have been 
too sparse to be macroscopically visible. Since, however, on incu¬ 
bation under moist conditions a copious production of sporulating 
fructifications ensues, it might be wrong to assume that the “black 
mold" described by Marquez could not possibly have been produced 
by the leafspot parasite. The total of microscopic detail given by 
Marquez is equally difficult to reconcile with the morphology of 
either species alone. From 20 measurements of conidiophores he 
found these structures to vary from 96 to 148 /x in length and from 
