266 
Journal of Agricultural Research 
Vol. XXIX, No. 6 
Table II .—Infection of barley by Ustilago nuda in the greenhouse in 1923-24, by 
flower and seed inoculation a 
Number of plants 
Number of heads 
Variety 
Type and stage of inoculation 
Total 
Smut¬ 
ted 
Per 
cent of 
smut 
Total 
Smut¬ 
ted 
Per 
cent of 
smut 
Alaska.. . _ 
3. Pollen shed__ 
81 
3 
3. 70 
233 
13 
5 58 
Do_ 
4. Milk stage_ 
85 
2 
2. 35 
281 
4 
1. 42 
Do_ 
5. Dehulled, uninoculated_ ... 
15 
0 
0 
41 
0 
0 
Do__ 
6. Dehulled, inoculated-. 
47 
36 
76. 60 
188 
148 
78. 72 
0 
Do_ 
7. Hulled, uninoculated_ 
30 
0 
0 
115 
0 
Do.. 
8. Hulled, inoculated_ _ 
42 
6 
14. 29 
144 
12 
8. 33 
Greece.. 
3. Pollen shed. 
64 
1 
1. 56 
210 
1 
0 48 
Do... 
4. Milk stage_ _ 
19 
1 
5. 26 
84 
9 
10. 71 
Do_ 
5. Dehulled, uninoculated_ 
29 
0 
0 
101 
0 
0 
Do.. 
6. Dehulled, inoculated_ 
49 
31 
63.27 
142 
80 
56. 34 
Do_ 
7. Hulled, uninoculated_ 
23 
0 
0 
69 
0 
0 
Do_ 
8. Hulled^ inoculated_ 
42 
0 
0 
124 
0 
0 
Han River_ 
3. Pollen shed... 
5 
0 
0 
14 
0 
0 
Do_ 
4. Milk stage_ 
(*) 
(*) 
( b ) 
123 
4 
3.25 
Do_ 
5. Dehulled, uninoculated_ 
11 
0 
0 
44 
0 
0 
Do. 
6. Dehulled, inoculated_ 
33 
29 
87.88 
146 
132 
90. 41 
Do__ 
7. Hulled, uninoculated_ 
33 
2 
6.06 
110 
3 
2. 73 
Do__ 
8. Hulled, inoculated._ 
46 
9 
19. 57 
127 
25 
19. 69 
Nakano Wase_ 
1-3. Anthers green to pollen shed.. 
104 
0 
0 
375 
0 
0 
Do. 
4. Milk stage_ _ 
65 
0 
0 
284 
0 
0 
Do_ 
5. Dehulled, uninoculated_ 
17 
0 
0 
73 
0 
0 
Do_ 
6. Dehulled, inoculated___ 
46 
0 
0 
167 
0 
0 
Do_ 
7. Hulled, uninoculated__ 
32 
0 
0 
110 
0 
0 
Do. 
8. Hulled i inoculated_ 
35 
0 
0 
127 
0 
0 
Texas W inter _ 
2-3. Pollen shedding to shed 
72 
5 
6.94 
187 
19 
10.16 
Do_ 
4. Milk stage_1___ 
54 
9 
16.67 
210 
42 
20.00 
Do. 
5. Dehulled, uninoculated. 
9 
1 
11.11 
21 
3 
14.29 
Do... 
6. Dehulled, inoculated__ 
14 
14 
100.00 
114 
114 
100.00 
Do_ 
7. Hulled, uninoculated_ 
35 
0 
0 
154 
0 
0 
Do.. 
8. Hulledj inoculated-..-.. 
37 
6 
16.22 
133 
15 
11.28 
Wisconsin Winter 
2-3. Pollen shedding to shed_ 
79 
4 
5.06 
274 
9 
3.28 
Do. 
4. Milk stage__ 
42 
0 
0 
151 
0 
0 
Do . 
5. Dehulled, uninoculated_ 
26 
0 
0 
89 
0 
0 
Do. 
6. Dehulled , inoculated... 
40 
21 
52.50 
143 
73 
51.05 
Do. 
7. Hulled, uninoculated_ 
21 
0 
0 
75 
0 
0 
Do_ 
8. Hulled^ inoculated_ . 
39 
6 
15. 38 
160 
24 
15.00 
a The type of inoculation is referred to by number in the second column from the left in this table. The 
numbers refer to the explanations of time and method of inoculation given above. 
b Not counted. 
The smut records in Table II show 
strikingly that seedling infection takes 
place when the mature seed is dehulled 
and inoculated with spores of Ustilago 
nuda (PI. 1, B). There evidently was a 
small amount of natural infestation in 
the seed used as two smutted plants oc¬ 
curred in one of the Han River controls 
and one plant in one of the Texas 
Winter controls. Other controls were 
smut-free (PL 1, A). The seed was not 
disinfected in any case as there was a 
possibility of injuring the vitality and 
interfering with the results. 
Apparently some infection was ob¬ 
tained in some cases by dusting the 
spores on the stigma and ovary at 
flowering time and afterward. This 
appears to be true for all varieties ex¬ 
cept Han River and Nakano Wase, 
The percentages of infection, however, 
are not as high as have been obtained by 
previous investigators using this method 
of inoculation. As suggested by Jen¬ 
sen (12), there is a possibility that the 
flowers were infected, and also a pos¬ 
sibility that the spores remained be¬ 
tween the glumes and the kernel and 
germinated and produced seedling in¬ 
fection when the seed germinated. 
Microscopic examination three days 
after the flowers were inoculated 
showed that many of the spores had 
germinated within the flowers of 
Alaska barley. No infections were 
found. This limited examination does 
not prove, by any means, that infection 
does not take place. Neither does it 
prove that the ungerminated spores 
are not finally responsible for infection. 
Even though infection takes place in 
the flower, which seems entirely pos- 
EXPLANATORY LEGEND FOR PLATE 1 
Infection of Han River barley by Ustilago nuda. Plants grown on bench in greenhouse. 
A. —Seed dehulled and uninoculated. All plants remained smut-free 
B. —Seed dehulled and inoculated with spores of U. nuda; 87.88 per cent of the plants and 90.41 per cent of 
the heads were smutted. 
