Mar. 17 ,1923 Influence of Soil Temperature on Seedling-Blight 
863 
The percentage of stand as well as the average mean soil temperature 
and mean daily soil temperature are given in Tables XI and XII and 
shown graphically in figures 2 and 12. 
Table XI. —Average soil and air temperatures during germination periods of Marquis 
wheat at Madison , Wis., in the spring of IQ2I 
Duration of germination period. 
Average soil tempera¬ 
tures, 4 inches deep. 
Average soil tempera¬ 
tures, 6 inches above soil. 
Num¬ 
Dates. 
ber of 
Mean. 
Min. 
Max. 
Mean. 
Min. 
Max. 
days. 
°C. 
°C. 
•c. 
# C. 
•c. 
•c. 
Mar. 19 to Apr. 9. 
21 
4.6 
2.8 
7.8 
7-3 
2.4 
12 ^ 4 
Mar. 26 to Apr. 9. 
14 
4.8 
3-2 
8.4 
7-7 
2.4 
13*3 
Apr. 11 to 25... 
14 
7-7 
5-4 
IO. 7 
8.9 
4.8 
12. 9 
Apr. 29 to May 8 . 
9 
10.5 
6. 5 
14. 7 
8-5 
3-5 
i 3 * 5 
May 20 to 25. 
5 
19. 6 
i 5-4 
23-9 
20. 8 
15-4 
26. 4 
June 20 to 24. 
4 
22. 5 
19. 6 
26. 7 
21. 0 
17. 2 
27.7 
Table XII. —Relation of date of seeding to the development of seedling-blight of Mar - 
quis wheat at Madison , Wis., in 1Q21 
Date of seeding. 
Average 
number 
of days 
for emer¬ 
gence. 
Average percentage of stand. 
Clean seed 
not 
inoculated. 
Clean seed 
inoculated 
with 
Gibberella 
saubmetii. 
Naturally 
scabbed 
seed. 
Mar. 19. 
21 
40. 6 
35-6 
24.0 
Mar. 26. 
14 
71. 6 
47.6 
49.6 
Apr. 11 . 
14 
75-2 
70. 0 
26. 4 
Apr. 29. 
9 
71.7 
35-8 
17.8 
May 20. 
5 
83.0 
39-6 
21. 2 
June 20... 
4 
52.0 
49.2 
In general, the results in the second spring showed the same tem¬ 
perature responses as those of the previous year. The early seedings 
gave the highest stand of healthy plants, although some blight appeared 
in these plots, due probably to the fluctuating soil temperature and 
moisture. In all three germination periods of the first seedings the mean 
daily soil temperature was around or above 12 0 C. for several days at a 
time. Likewise, especially in the second germination period, the soil 
moisture was low enough to be an important factor in producing blight. 
The following two seedings both gave high percentages of blight, or, 
stating it reversely, a poor stand. The last seeding corresponded with 
the last seeding of the previous spring, which demonstrated that the 
attack of the parasite was probably checked by the high soil temperatures. 
