202 
Journal of Agricultural Research 
Vol. XXVI, No. 5 
Table II .—Effects of soil temperatures on the infection of Marquis (spring) wheat 
seedlings with Helminthosporium sativum, Culture 51a, at Madison, Wis ., in IQ20—21 
Experiment 1. 
Experiment 2. 
Experiment 3. 
Artificially inoculated soil. Started 
Nov. 24, 1920; ended Jan. 20, 
1921. Soil moisture 37.3 per cent 
of moisture-holding capacity. 
Artificially inoculated soil. 
Started Feb. 7. 1921; ended 
Feb. 23, Mar. 12 and 18, 1921. 
Soil moisture 44.4 per cent of 
moisture-holding capacity. 
Artificially inocula 
Started Mar. 3, 15 
Mar. 21, 1921. Soil 
43.2 per cent of moi 
ing capacity. 
ted seed. 
21; ended 
moisture 
sture-hold- 
Average 
soil tem¬ 
peratures. 
Number 
of plants. 
Infection 
rating. 
Average 
soil tem¬ 
peratures. 
Number 
of plants. 
Infection 
rating. 
Average 
soil tem¬ 
peratures. 
Number 
of plants. 
Infection 
rating. 
°C. 
8 
12 
16 
20 
24 
28 
32 
40 
41 
37 
33 
25 
22 
20 
1-3 
21. I 
63.O 
73 - 7 
68.0 
69. 6 
61. 3 
°C. 
aS 
&12 
c 16 
c 20 
C24 
C28 
-32 
c 35 
72 
72 
73 
78 
79 
7 i 
27 
27 
24. 6 
61. O 
40. 8 
52.3 
76.3 
82. 1 
87.6 
88.8 
°C. 
16 
20 
24 
28 
32 
34 - 5 
103 
IOO 
92 
90 
70 
54 
32. 6 
75-4 
87.7 
9 $-S 
79.8 
58.0 
Experiment 4. 
Experiment 5- 
Summary A 
Artificially inoculated seed. Started 
Nov. 19,1921; ended Dec. 17,1921. 
Soil moisture 59.7 per cent of 
moisture-holding capacity. 
Naturally infected loam soil. 
Started Nov. 19, 1921; ended 
Dec. 17, 1921. Soil moisture 
£9.7 per cent of moisture-hold¬ 
ing capacity. 
Average amount of infection at 
each soil temperature in five 
experiments with Marquis 
(spring) wheat. 
Average soil 
tempera¬ 
tures. 
Number 
of plants. 
Infection 
rating. 
Average 
soil tern* 
peratures. 
Number 
of plants. 
Infection 
rating. 
Average 
soil tem¬ 
peratures. 
Average 
number 
plants 
per 
experi¬ 
ment. 
Infection 
rating. 
# c. 
12 
16 
20 
24 
28 
32 
34-5 
82 
74 
63 
67 
44 
67 
41 
17. I 
33-3 
46.9 
64. 7 
94.2 
83-4 
86.7 
°C. 
12 
16 
20 
24 
28 
32 
34-5 
98 
94 
74 
86 
7 i 
58 
45 
7-9 
2C. 2 
36. 2 
60. 9 
64. O 
75-2 
73-3 
°C. 
8 
12 
16 
20 
24 
28 
32 
34 - 5 - 35 - 0 
<6. 0 
73-2 
76. 2 
69. 6 
69.8 
59-6 
48.4 
41. 7 
1-3 
15-4 
38.9 
5 M 
7 i -5 
81.1 
77*4 
76.7 
a Ended Mar. x8. 
b Ended Mar. 12. 
d Thb^tmmiary does not include the 8° or 12° temperature data from experiment 2, since these are for 
older plants. 
