Mar. 22, 1924 Nematode Disease Caused by Tylenchus tritici 943 
head threshed by hand. The results shown in Table XIII are con¬ 
clusive evidence of the fact that the larvae can bring about infection 
when galls are placed in the soil as far as 12 inches (30 cm.) from the seed. 
The larvae seem able to travel vertically as far as 30 cm. Marcinowski 
(77) buried galls at depths of 3, 6, 10, 15, and 30 cm., respectively. At 
the first four depths she secured head infection, the greatest being at 
3 cm. At 30 cm. no galls were formed although a few larvae reached 
the plants. 
The writer’s results show greater movement of larvae than this, as 
he found that galls buried 30 cm. deep produced some head infection. 
Galls were buried at depths of 2, 4, 6, 9, 12, and 15 inches, respectively, 
in bottomless wooden frames sunk into the ground. In another series, 
boxes with closed bottoms were used to eliminate a possible complica¬ 
tion due to water rising in the soil. Winter wheat was sown in these 
frames in October and in the following June the heads were collected 
and threshed by hand. The results are shown in Table XIV (A) and (B). 
Table; XIV .—Relation between the depth at which galls were placed in the soil and the 
resulting infection of wheat heads , Arlington Experiment Farm , IQIQ-20 
A. IN BOTTOMLESS FRAMES 
Depth (inches). 
Exam¬ 
ined. 
Number 
Healthy. 
of heads. 
Infected. 
Number. 
Per cent. 
120 
70 
5 ° 
® 4 « 
90 
60 
30 
33 
6. 
40 
30 
10 
25 
66 
S 3 
13 
20 
60 
54 
6 
xo 
56 
56 
0 
0 
B. IN FRAMES WITH CLOSED BOTTOMS 
46 
3 i 
IS 
33 
28 
22 
6 
21 
33 
28 
S 
15 
88 
77 
11 
13 
C. IN METAL CYLINDERS IN FIELD 
12 
6 
6 
SO 
15 
9 
6 
40 
22 
14 
8 
36 
28 
19 
9 
• 32 
25 
20 
5 
20 
3 © 
27 
3 
10 
a Heads somewhat shattered by birds. 
Similar results were obtained in the field. Galls were buried at different 
depths in circular plats, and wire cages were used to keep out birds and 
rodents. Wheat was sown in the fall and when the heads were harvested 
the following June the results given in Table XIV (C) were obtained. 
At Madison, Wis., in 1922, this experiment was repeated, but spring 
wheat was used. The galls, some of which were ground to insure early 
liberation of the larvae, were buried at the following respective distances 
