440 
Journal of Agricultural Research voi. xxvn, no. r 
recorded in a few varieties. Obviously, in these cases, inoculating the 
seeds with dry spores gave as high a percentage as could have been 
obtained if the seeds had been inoculated with soaked or even germinating 
spores. These results would indicate that the period favorable for 
infection is before the seedling comes through the ground, or before the 
coleoptile is broken. 
In order to test the possibility of infection during the tillering stage, 
when new shoots are produced from the crown of the plant, the following 
experiments were conducted: One lot of smut-free seed of Harvest 
Queen, Little Club, and White Federation, the same varieties used in 
lie foregoing experiments, was sown in clean soil on November 28, 1921. 
A similar lot was inoculated with dry spores of the previous season 
and sown on the same day. Three rows of each variety in the two lots 
were sown. On December 13, when the plants in both lots had de¬ 
veloped one strong leaf and a small second one, they were removed 
from the soil. Only two rows of each variety in the two lots were re¬ 
moved. For a control the third row in each instance was not disturbed. 
The uninoculated plants then were inoculated by rolling the roots and lower 
part of the stem in dry spores and were transplanted to the rows in which 
the inoculated seed had been sown. The inoculated plants were washed 
free from all soil particles and the old attached seed washed and brushed 
until all traces of the spores were removed. They then were planted 
in the clean soil where the uninoculated seed had been sown. Thus, 
there was an exact reversal of position. Both sets also were inoculated, 
one on the original seed and the other when the plants were about two 
weeks old. The results are given in Table VIII. 
Table VIII .—Infection of three varieties of wheat hy Urocystis tritici after inoculating 
seed and seedlings in the greenhouse at Arlington Experiment Farm t Rosslyn, Va., 
from November 28 to December 13, IQ21 
Variety. 
Control. 
Uninoculated 
seed; seedlings 
inoculated and 
transplanted 
to infested soil. 
Inoculated seed; 
seedlings washed 
and transplanted 
to clean soil. 
Clean seed in 
clean soil. 
Inoculated seed 
in clean soil. 
1 Total num¬ 
ber plants. 
Infected 
plants. 
Total num¬ 
ber plants. 
Infected 
plants. 
Total num- 
| ber plants, j 
Infected 
plants. 
Total num- 
j ber plants. 
Infected 
plants. 
Harvest Queen. 
White Federation. 
Little Club. 
All varieties. 
16 
17 
17 
No. 
O 
O 
O 
P. ct. 
O 
O 
O 
18 
14 
14 
No. 
14 
II 
14 
P. ct. 
77.8 
78.6 
100 
30 
30 
35 
No. 
I 
O 
I 
P. Ct. 
3-3 
0 
2.9 
34 
20 
32 
No. 
30 
18 
30 
P. ct. 
88.2 
90.0 
93-8 
50 
O 
O 
46 
39 
84.8 
95 
2 
2.1 
86 
78 
90.7 
There was one plant each of Harvest Queen and Little Club infected 
in the lot which was inoculated when the plants were about two weeks 
old, but no infection appeared in White Federation. No other infection 
was noted on plants which were inoculated after the seedlings had 
emerged. There was 88.2 per cent or more of infection in each variety 
which was inoculated at the time the seeds were sown. From these 
results and from the data obtained in the previous experiment where 
