Journal of Agricultural Research 
Vd. XXIV, No. 7 
614 
covered with rust sori. Head infection, which usually indicates that 
the kernels are more or less infected, is common only in certain varieties 
of wheat. Chul (C. I. No. 2406), Dale (Dale Gloria, C. I. No. 4231), 
Talimka (C. I. No. 2495), Baart (Early Baart, C. I. No. 1697), Little 
Club (C. I. No. 4219), Jones Fife (C. I. No. 3452), and a number of 
others, are very commonly infected in the head even when the rest of 
the plant may not be heavily infected. Many times, the inside of the 
glumes and the kernels of plants of the above-named varieties may be 
heavily infected without the development of open sori on the outer 
surface of the glumes. Except in cases of very severe infection, only a 
few of the spikelets on each head are infected. 
If infection develops on the heads soon after they emerge from the 
boot, sterility of a large number of spikelets may result. (PI. Ill, A.) 
The kernels which develop in such heads usually are very badly shriveled. 
(PI. Ill, B, and PI. IV, A.) It is easily possible to pick out infected 
heads even though there be no open sori on the surface of the glumes 
and awns. Such heads are much lighter in color, being a yellowish 
green, while the rest of the plant is a normal green. Plate IV, A, 
shows a number of detached glumes from heads of Chul wheat collected 
at threshing time. The inside of these glumes shows an abundance of 
stripe-rust telia. 
Kernel infection by stripe rust is much more common in certain 
varieties of wheat than the author (6) found to be the case in wheat 
infected with stem rust. As high as 60 per cent of the kernels of certain 
varieties were found to be infected when grown in a rust nursery at 
Corvallis, Oreg., where a heavy infection of stripe rust was secured by 
artificial inoculation. Over 35 per cent of infected kernels were found 
in several samples of wheat grown under field conditions. It seems to 
the author that the amount of head infection, and consequently the 
amount of kernel infection, depends largely upon the climatic conditions 
at heading time, as well as upon the variety of wheat. 
EFFECT OF KERNEE INFECTION UPON GERMINATION 
The author has reported ( 6 ) that kernel infection by P. graminis 
tritici does not affect the germinating power of wheat to any appreciable 
extent. This has not been found true of wheat kernels infected with 
P. glumarum tritici. Numerous germination tests were made with several 
varieties of wheat which were badly infected with this rust. Parallel 
series of unrusted kernels from the same samples of seed also were 
germinated at the same time. The germination of the rusted seed 
averaged about 50 per cent of that of the unrusted seed. In some 
cases the germination was less than 25 per cent of that of the unrusted 
seed. By reference to Plate IV, B, it will be noted that infected 
kernels are very much shrunken. In many cases a cross section of an 
infected kernel revealed dozens of sori under the pericarp over prac¬ 
tically the entire surface of the kernel. In the case of wheat kernels 
infected with P. graminis tritici the sori usually were confined to the 
hilar region and were present only in limited numbers. 
