272 
Journal of Agricultural Research 
Vol. XXIX, No. 6 
Table IV.— Effects of Ustilago nuda on the emergence of barley seedlings from 
dehulled-inocnlated seed sown at two different depths , and the occurrence of loose- 
smut in the surviving plants 
Depth 
Number 
seedlings 
Percent- 
Number 
Percent- 
Variety 
Treatment 
sown in 
from 
age of 
of plants 
age of 
inches 
25 or 50 
emerg- 
smutted 
smut 
seeds 
ence 
From 25 
seeds 
Tennessee Winter_ 
Inoculated_ .._ 
X 
14 
56 
11 
78. 57 
Do_ 
Uninoculated... 
X 
22 
88 
0 
0 
Do_ 
Inoculated 
i y 2 
8 
32 
8 
100 . 00 
Do...... 
Uninoculated__ 
1)4 
21 
84 
0 
0 
Nakano Wase...__ 
Inoculated__ __ 
M 
15 
60 
0 
0 
Do... 
Uninoculated 
H 
23 
92 
0 
0 
Do___ 
Inoculated__ 
V/ 2 
7 
28 
0 
0 
Do_ 
Uninoculated _ 
23 
92 
0 
0 
Han River_ 
Inoculated_ 
% 
17 
68 
14 
82. 35 
Do__ 
Uninoculated . . 
% 
24 
96 
0 
0 
Do... 
Inoculated 
1 u 
o 4 
16 
2 
100.00 
Do_ 
Uninoculated. 
1H 
24 
96 
0 
0 
From 50 
seeds 
Do__ 
Inoculated... 
X 
37 
74 
34 
91.89 
Do........ 
Uninoculated_ 
X 
47 
94 
0 
0 
° Two died. 
The data in Table IV show that to barley seedlings grown from de- 
there was a marked reduction in emer- hulled-inoculated seed, the question 
gence of seedlings from dehulled-in- arose as to whether this injury was due 
oculated seed. This was true for all to infection and invasion of the tissues 
three varieties. The stands were much of the seedlings by the fungus or to the 
poorer from inoculated seed sown presence of large quantities of spores 
inches deep than from similarly treated on the naked germinating seed, which 
seed sown only of an inch deep, might have a toxic effect. The ex- 
The seedlings of Nakano Wase, a variety perimentation along this line was very 
which has not been known to become limited. It may be well, however, to 
smutted, were injured as severely (PI. present the meager evidence obtained. 
3, E and G) as those of the suscepti- The fact that plants grown from in- 
ble varieties, Tennessee Winter and oculated seed produced high per- 
Han River (PI. 3, A and C and PI. centages of loose-smut was sufficient 
4, A and C). The seedlings from evidence that infection of the seedlings 
the inoculated seed showed the same took place. Actual penetration of 
abnormalities as previously mentioned, the seedlings by the mycelium of the 
They were twisted, and yelloAvish in fungus also had been found in cyto- 
color, and some emerged at an acute logic studies to be discussed later, 
angle to the soil surface. After emer- A quantity of viable spores of Ustil - 
gence the leaves appeared somewhat ago nuda were placed in a test tube with 
stiff and later became bluish green in sufficient water to immerse them. The 
color, and waxlike streaks were notice- tube was corked and a standardized 
able, especially on the dorsal surface of thermometer inserted through the 
the first two leaves on some of the cork with the bulb extending into the 
abnormal plants. solution. The tube was then immersed 
for 15 minutes in water that ranged in 
Cause of Seedling Injury temperature from 59 to 61° C. This 
was done to devitalize the spores and 
After it had been definitely shown that at the same time, if possible, to prevent 
Ustilago nuda caused considerable in jury heating sufficiently high to destroy any 
EXPLANATORY LEGEND FOR PLATE 4 . 
Effects of viable and devitalized spores of Ustilago nuda on seedlings of Han River barley sown in flats 
in the greenhouse Feb. 25 and Mar. 8 ,1924. Seed aH dehulled except those producing plants shown in H. 
A.—Inoculated, sown X of an inch deep; 68 per cent emergence. 
B—Uninoculated, sown X of an inch deep; 96 per cent emergence. 
C. —Inoculated, sown \)4 inches deep; 16 per cent emergence. 
D. —Uninoculated, sown VA inches deep; 96 per cent emergence. 
E. —Uninoculated, sown 1)4 inches deep; 86 per cent emergence. 
F. —Inoculated with devitalized spores; sown 1 l A inches deep; 94 per cent emergence. 
G. —Inoculated with viable spores; sown VA inches deep; 48 per cent emergence. 
H. —Hulled; inoculated with devitalized spores; sown 1)4 inches deep; 98 per cent emergence. 
