43 2 Journal of Agricultural Research voi. xxvn. No. r 
periment was inoculated with spores collected in the greenhouse at Ross- 
lyn, Va., in 1921, and sown in the same greenhouse bench about 18 days 
later than the sowings recorded in Table II. Fourteen out of 15 of these 
plants, or 93.3 per cent, became infected. The seed and spores were from 
the same source as those used in rows 64 and 73, given in Table II, in which 
but 67.7 per cent of the plants became infected. Therefore it is reason¬ 
able to expect that had the conditions at the time of sowing been simi¬ 
larly varied for all the spore lots used in the inoculations noted in Table 
II, different percentages of infection might have been obtained. How¬ 
ever, the results serve to indicate that the infective power of spores is 
not destroyed even though they are stored two or three years under 
laboratory conditions. 
In the spring of 1923 germination tests were made with spores from 
the same collections listed in Table II. In all instances good germination 
was obtained. Thus it has been shown that the spores collected in Aus¬ 
tralia and Illinois in 1919 were viable after having been kept for four 
years in the laboratory. 
In order to test the infective power of fresh spores, seed of Harvest 
Queen was inoculated with spores from infected green leaves collected 
on January 5, 1922, and sown in clean soil on January 6, 1922, together 
with one uninoculated row and one row inoculated with dry spores of 
the previous season for controls. The fresh spores produced an infection 
of 5.7 per cent and the dry spores 47 per cent, while no infection devel¬ 
oped in the uninoculated row. Again in March, 1923, 30 seeds each of 
Harvest Queen, Hard Federation, and Little Club were inoculated with 
spores which had been collected the same day, and then were sown in 
three 10-inch pots containing garden soil autoclaved for 15 minutes at 
15 pounds pressure. The pots were set in the soil on a greenhouse bench 
in order to lessen drying out and to prevent rapid temperature changes. 
Two plants of Hard Federation, or 6.7 per cent, became infected, but no 
infection developed in Harvest Queen or Little Club. Thus it was 
shown that wheat plants can become infected by fresh spores, though 
the percentages of such infection may be quite small. 
OVERWINTERING OF SPORES 
It having been shown that soil infestation was an important factor 
in the dissemination of flag smut, and one which made seed treatment 
partially ineffective, it was thought desirable to secure experimental 
data on the overwintering of the spores in the soil. On such information 
recommendations could be based for such practices in soil management 
as might control the disease. 
The following experiment was conducted to determine the ability of 
spores to overwinter in the soil at Granite City, Ill., in the flag-smut area. 
Forty-two small cylindrical wire baskets about 1 inch in diameter and 3 
inches long were filled with the various mixtures of different soils, diseased 
leaves, and spores of the previous season, as given in Table III. Besides 
the native black alluvium of Granite City, there were used sandy loam 
and basaltic soils from Madison, Wis., and Pullman, Wash., respectively. 
These baskets were buried in the ground at different depths on October 
6, 1921. 
One-third of the baskets were dug up on November 1, one-third on 
November 28, and the final third on April 10, 1922, and the contents 
sent to the laboratory in small glass vials. A soil suspension was made 
from each, using about 30 cc. of tap water. The spores in part were 
