10 
BULLETIN 1239, U. S. DEPARTMENT OF AGRICULTURE. 
last of March, after which date it was thought necessary to substitute 
Early Wilbur, a spring wheat of even greater bunt susceptibility 
than Hybrid 143. The difference between the two in this respect is 
shown by three parallel sowings on March 22, 26, and April 4 (Table 8) . 
Table 8. — Relation of soil temperature to hunt infection, as indicated by the 
percentages of bunted plants of wheat varieties sown on successive dates at 
Pullman, Wash., during stated periods. 
[The mean temperatures observed are for intervals following sowing as follows: 7 davs for the periods 
August 1-1 to September 28, 1914, and from April 24 to June 3, 1915; and for 10 davs for the periods from 
October 3 to November 23, 1915.1 
Number of plants. 
Plants 
infected. 
Mean 
Date of sowing. 
Bunt 
free- 
Wholly Partly 
bunted, bunted. 
soil tem- 
perature 
HYBRID 143. 
In 1914: 
7 
15 
38 
30 
31 
. 70 
55 
75 
52 
38 
20 
23- 
8 
1 1 
2 
8 8 
1 1 
1 
4 2 
2 3 
3 
3 
8 14 
42 37 
36 53 
67 34 
54 30 
Per crnt. 
22.2 
11.8 
29.6 
6.3 
3.1 
7.9 
8.3 
3.8 
5.5 
36.7 
79.8 
79.5 
93.5 
91.3 
94.6 
95.3 
94.4 
92.9 
93.3 
99.1 
97.1 
96.6 
97.4 
98.7 
97.4 
96.1 
93.5 
97.6 
92.5 
91.2 
8S.6 
S2.6 
20.6 
98.9 
98. 9 
94.6 
84.2 
90.7 
56. 3 
100.0 
97.7 
86. i 
95. 5 
75. 2 
63.1 
.".7.7 
81.1 
75. I 
•c. 
21.4 
20.9 
20.6 
August 21 
20.4 
August 24 
20.3 
August 26 
19.8 
August 28 
19.5 
19.7 
18.2 
15.5 
11.9 
September 14 
10.3 
10.8 
12.4 
6 ! 70 35 
5 60 42 
16.6 
14.9 
September 23 
6 
11 
8 
1 
4 
4 
3 
2 
2 
3 
4 
4 
9 
14 
16 
67 35 
101 42 
82 29 
96 14 
120 14 
103 12 
104 9 
142 12 
75 1 
66 7 
57 1 
156 10 
94 17 
130 15 
112 12 
15.5 
September 25 
14.7 
September 28 
12.1 
October 3 
9.7 
October 5 
10.0 
October 8 
10.0 
October 11 
9.4 
October 14 
8.7 
October 18 
7.4 
October 21 
8.0 
October 25 
8.3 
October 31 
6.2 
5.8 
4.9 
3.7 
2S 97 36 
100 13 13 
2 138 39 
2 145 33 
10 1 147 2S 
22 si 36 
9 65 23 
hi 
3.6 
November 2-3 ' 
2.7 
In 1915: 
March 3 
March 8 
March 13 
March 22 
( 2 ) 
March 26 
April 4 
EARLY WILBUR. 
In 1915: 

3 
20 
7 
40 
55 
189 
104 
106 
136 
85 
52 
12 
21 
18 
14 
36 
42 
37 
41 
21 
March 26... 
\ ( 3 ) 
April 9 
April 24 
12.3 
63 ] 49 
25 66 
33 so 
15.4 
May x 
13.3 
May 23 
14.3 
136 
19.3 
1 Did not como up until spring. 
- From Mar. 3 to Apr. 4, moan between 1 
* Temperature record not reliable. 
7° and 4.4' C. (Thermograph out of adjustment.) 
