216 
Jo urnal of Agricultural Research 
Vol. XXIX, No. 5 
many times longer than wide (fig. 3, B). 
Thus, if infection obtains near the tip 
or distal end of a leaf, the affected area 
widens as the fungus extends toward 
the base of the leaf. 
The telial stage is not at all uncom¬ 
mon, especially later in the crop season. 
It may appear in any organ or structure 
of the host attacked by the uredinial 
stage of the rust, namely, leaf blades, 
sheaths, stalks, glumes, and kernels. 
In each of these the telia become 
readily evident from their dark brown 
to black color. They may occur in 
some part, usually the older portions, 
of the uredinial lesions; or they may 
develop quite independently. On the 
leaves and stalks, the telia commonly 
there is considerable difference in the 
color of the uredinia on different 
grasses. Whether this is due to any 
actual difference in color of the uredi- 
niospores or is traceable solely to 
depth of spore mass has not been de¬ 
termined. Glume infection has been 
noted upon Bromus marginatum and B. 
sitchensis, but has not yet been ob¬ 
served on any other of the wild-grass 
hosts. 
LIFE HISTORY AND MORPHOLOGY 
OF THE ORGANISM 
Under congenial climatic condi¬ 
tions, the urediniospores of Puccinia 
qlumarum retain their viability through- 
Fig. 2.—Schematic drawing of a cross section of a rust-infected wheat kernel showing pockets or inclusions 
of rust spores within the pericarp 
coalesce end to end, thus forming long, 
narrow, dark brown or black lines. On 
the glumes, these sori occur most com¬ 
monly, although not exclusively, on 
the inner surface and are variously 
grouped. Oh the kernels, they may be 
external and evident, variously scat¬ 
tered or grouped, anywhere on the 
lobes; or they may be internal, that is, 
within the pericarp in spore pockets 
after a manner not unlike that noted 
for the uredinia (fig. 2). 
ON OTHER GRAINS AND GRASSES 
The stripe-rust lesions on cereal and 
grass hosts other than wheat are in 
most respects similar to those on wheat. 
It has been observed, however, that 
out the winter months and thus con¬ 
stitute an important factor in facilitat¬ 
ing the natural spread of infection. 
Experiments conducted by Eriksson 
and Henning (4) led them to conclude 
that the germination of the uredinio¬ 
spores was dependent on the influence 
of low, even freezing temperatures. 
Particularly did this seem true of 
spores which had matured early in the 
season and therefore had been sub¬ 
jected to prolonged exposure to light 
and desiccation. One of the writers 
(Hungerford), however, has experi¬ 
enced no difficulty in securing prompt 
germination of these spores without 
first subjecting them to subnormal 
temperatures. 
