714 
Joumal of Agricultural Research voi. xxxi, No. 8 
euchlaenae therefore can not be decided until additional information 
on the African form becomes available. It may be added that 
Zimmerman makes no mention of any leafspot on maize, although his 
account of maize rust makes it evident that this host came under 
observation. 
INOCULATIONS ON RICE AND SUGAR CANE 
Morphologically, the parasite causing leafspot of maize shows much 
similarity to Helminthosporium oryzae , H. sacchari Butler, and H. 
leersii Atk. Perhaps its most obvious distinctive characteristic is 
found in the curvature of the conidium, this curvature being more 
pronounced than in any large-spored congeneric form known to the 
writer. The conidia of both H. sacchari and H. leersii would appear 
to be somewhat inferior in diameter to those of the maize parasite. 
Owing to a considerable degree of variability manifested by species 
of Helminthosporium under different conditions, it was believed 
advisable to determine the possible pathogenicity of the Florida 
organism on rice ( Oryza sativa L.) and sugar cane ( Saccharum off- 
cinarum L.), since these hosts are cultivated in tropical and subtropi¬ 
cal regions where leafspot of maize is presumably of fairly widespread 
occurrence. 
For the inoculation tests, plants grown in 5-inch pots in the green¬ 
house were used. The experimental material consisted of 24 pots 
each of sweet corn, dent corn, rice, and sugar cane, the maize being 
planted 3 seeds to a pot, the rice 10 seeds to a pot, and the cane 
started with a single cutting to each pot. Inoculations were begun 
25 days after planting, when all the pots showed very satisfactory 
E owth, and were repeated five times, at intervals of four days, the 
st material used thus being 45 days old, and in the case of the maize 
and cane, so large as to be somewhat unwieldy. Three pots of 
each host were inoculated at a time, by applying with an atomizer 
a suspension of conidia derived from pure cultures of the leafspot 
fungus on plates of corn-meal agar. Immediately after inoculation 
the plants, together with an unsprayed pot of each host as control, 
were incubated in a large moist chamber provided with glass windows. 
On examining the maize plants 36 hours after inoculation, most of 
the leaves were found to be covered with hundreds of watersoaked 
spots varying in diameter between 1.0 and 2.5 mm., with the center 
occupied by a very minute whitish speck (pi. 2, A). The control 
plant immediately after this period showed no ill effects from 
confinement in moist atmosphere, but at the end of 48 hours showed 
symptoms of etiolation which became increasingly pronounced as 
incubation was continued to 72 or 96 hours. Even after 96 hours 
all except the lowest foliage of the controls was still functional, 
whereas the leaves of the inoculated plants had utterly collapsed 
and were converted into wet, softened structures drooping flabbily 
from the stalks. 
An apparently more natural course of development of the infec¬ 
tion resulted when the experimental plants were removed from the 
damp chamber to the greenhouse 24 or 36 hours after inoculation. 
Portions of the leaves in which the infections were very numerous 
withered very soon, to be sure, the healthy parts dying evidently 
from an interruption of the water supply, but where a more moderate 
