FOOT-ROT DISEASES OF. WHEAT IN AMERICA 88 
Helminthosporium tetramera n. sp. 
Conidiophores, dark olivaceous to brown, very 
irregular. Simple or compound, septa 5 to 50 
microns apart. Conidia are produced at irregular 
distances from the bases of the conidiophores 
(fig. 5). 
Conidia chiefly 4-celled, borne in clusters of 2 
or 8 to 50 or more, dark olivaceous tg brown, 
usually rather symmetrical in shape, tapering 
toward the rounded ends (fig. 5). Length meas- 
urements range from 20.4 to 40.8 microns, but only 
a very small percentage of the spores possesses 
the extreme dimensions. Of the spores measured 
48 per cent were from 30.6 to 34.0 microns 
long, 30.6 microns being the most common length. 
The width measurements range from 8.5 to 20.4 
microns, and, as in the case of the length meas- 
urements, only a small percentage of the spores 
possesses the maximum and minimum width dimen- 
sions. The diameters, however, seem to vary con- 
siderably less than the length measurements, as 
74.2 per cent of the spores measured were 10.2 
to 183.6 microns wide, 13.6 microns being the most 
common width. Mature conidia are practically 
always 4-celled. Even in the case of the longer 
sizes it is exceedingly rare to find conidia having 
more than four cells. The spore walls are not jy 5-—Hyphal thread, coni- 
constricted at the septa. There seems to be very diophore, and conidia of 
little, if an, change in spore characters when the Helminthosporium tetramera 
fungus is cultured artificially. 
On potato-glucose agar the fungus produces numerous long simple or 
branched sclerotia. These are made up of a hard white pseudoparenchyma 
with an outer black layer or rind. Many hyphal strands develop from this 
rind, but no conidia have been found on them. 
Associated with a foot-rot of winter wheat, collected near Woodward, Okla., 
in the spring of 1923. 
OTHER FUNGI CAPABLE OF CAUSING FOOT-ROTS 
In addition to the parasites which have been discussed, certain 
other organisms are constantly referred to in the literature dealing 
with the foot-rot diseases of wheat. European writers (23, 70) have 
long considered Ophiobolus herpotrichus an important wheat para- 
site, and Frank (23) is of the opinion that this organism is the chiet 
cause of wheat foot-rot in certain German Provinces. This organism 
has not yet been reported in America. 
Various European papers refer to several species of Fusaria in 
connection with foot-rot, and in this country Atanasoff (7) reported 
that the Fusarium stage of Gibberella saubinetii will cause a foot- 
rot on wheat. The same writer (2) published further on the 
Fusarium diseases of cereals and claims that several species of this 
genus cause foot-rot of wheat both in Europe and America. Accord- 
ing to Johnson and Dickson (34) G@. saubinetiz is widespread through- 
out the principal wheat regions of this country and causes consider- 
able injury to the heads and grain, but in spite of this wide 
distribution and damage to the aboveground parts the writer has 
not found it associated to any great extent with other foot-rots he 
has studied. In certain localities this parasite has been found asso- 
ciated with Helminthosporium satiwum and Ophiobolus graminis, 
but it appears that the last-mentioned organisms were the chief 
causes of the foot-rot conditions under study. 
