274 
Journal o f Agricultural Research y 0 i. xxix, No. 6 
toxine that the spores might contain. 
The spores were then filtered from the 
solution and left on the filter to dry. 
A germination test proved these spores 
to. be dead. The untreated spores ger¬ 
minated more than 80 per cent. 
Five dehulled seeds of Han River 
barley inoculated with the devitalized 
spores and sown on moist sterile filter 
paper in a Petri dish showed no signs 
of abnormality while some of the seed¬ 
lings from seed similarly treated but 
inoculated with viable spores showed 
some of the abnormal symptoms 
observed in seedlings from seed inocu¬ 
lated with viable spores and sown in 
the soil. The abnormal seedlings were 
found through microscopic examina¬ 
tion to be heavily infected by Ustilago 
nuda. 
On March 8, 1924, duplicate lots of 
hulled and dehulled seed of Han River 
and Nakano Wase barleys from the 
crop of 1921 were inoculated according 
to the regular method, one lot of each 
with devitalized spores and the second 
lot with viable spores of Ustilago nuda. 
A third lot was left uninoculated. All 
lots of the seed were sown 1J^ inches 
deep in flats in the greenhouse. This 
seed was known to have a slight amount 
of natural infestation (Table V), but 
not sufficient to interfere seriously with 
the results as is shown by the controls 
in Table V. Seed of Red Wave wheat, 
one lot inoculated with devitalized 
and another with viable spores of 
U. nuda , and of an uninoculated con¬ 
trol, was sown in similar flats to deter¬ 
mine the effect of these spores on wheat 
seedlings. If the injury of the barley 
seedlings were due to a toxin produced 
on the surface of the seed by either the 
germinated or ungerminated spores, 
wheat seedlings might also be injured 
by inoculating the seed with these 
spores of U . nuda. 
The emergence of the barley seedlings 
from dehulled seeds inoculated with 
viable spores was poor (PI. 4, G, and PI. 
8, E), as had been previously noted with 
that type of inoculation. The spores 
killed bv heat had no visible effect on 
the seedlings (PI. 4, F and H, and PI. 8, 
D and F). The stands were as good 
as those of the control (PI. 4, E, and 
PI. 8, B, C, and H). A high percentage 
of loose-smut developed in Han River 
plants from the dehulled seed which 
had been inoculated with viable spores 
(PI. 7, C). More smut developed in 
plants from hulled seed of Han River 
inoculated with viable spores than 
occurred in corresponding plants from 
uninoculated seed. Plants from seed 
inoculated with devitalized spores were 
smut-free (PI. 7, D). None of the 
wheat seedlings showed any signs of 
injury regardless of how the seed was 
treated. The emergence was equally 
good in each case and the plants were 
normal at maturity. (Table V.) 
Table V.— Effects of viable and devitalized spores of Ustilago nuda on barley and 
wheat seedlings from seed sown 1inches deep in the greenhouse 
Variety 
Treatment previous 
to inoculation 
Type of spores 
used 
Number 
of plants 
from 50 
seeds 
Per cent 
of emer¬ 
gence 
Number 
of 
smutted 
plants 
Per cent 
of smut 
Han River. 
Dehulled_ 
None.. . 
43 
86 
1 
2. 33 
Do. - 
_ _ do . 
Devitalized_ 
47 
94 
2 
4.26 
Do. 
. do. _ 
Viable_ 
24 
48 
24 
100 . 00 
Do_ 
Hulled_ 
None. _ 
49 
98 
3 
6.12 
Do_ 
__ do. ... 
Devitalized_ 
44 
88 
0 
0 
Do__ 
_do. _ 
Viable_ 
48 1 
96 
5 
10. 42 
Nakano Wase . 
Dehulled._ 
None. .. _ 
43 
86 
0 
0 
Do 
_do .. 
Devitalized_ 
41 
82 
0 
0 
Do. 
_do_:_ 
Viable_ 
16 
32 
0 
0 
Do . 
Hulled :.. 
None__ 
46 
92 
0 
0 
Do__ 
_do_ 
Devitalized.._ 
45 
90 
0 
0 
Do. 
__do___ 
Viable..._ 
<6 
92 
0 
0 
Red Wave (wheat).. 
No treatment__ 
None.. _ 
48 
96 
0 
0 
Do ... 
do ___ 
Devitalized.._ 
49 
98 
0 
0 
Do_ 
_do. _ 
Viable_ 
49 
98 
0 
0 
1 
EXPLANATORY LEGEND FOR PLATE 5 
Infection of Tennessee Winter barley from dehulled seed by Ustilago nuda. Same plants shown in Plate. 3, 
A to D. 
A. —Seed inoculated. Plants 78.57 per cent smutted. 
B. —Seed uninoculated. No smut. 
C. —Seed inoculated. Plants 100 per cent smutted. 
D. —Seed uninoculated. No smut. 
