SOIL DISINFECTION WITH HOT WATER. 
13 
Table V. — Soil-disinfection tests with tomato plants grown in shallow bench sections, 
with hot-water treatment, in May and June, 1918. 
[The bench sections were filled with nematode and fungus infested soil thoroughly mixed by sifting.} 
Application of boil- 
ing water (at 98° C). 
1 
ft 
o 
Root infection on June 13 (end of experiment). 
Plant notes, 
May 28. 
Bench 
section. 
No 
1 
& 
S 
o 
E-i 
o 
fi | 
< 
Nematode. 
Rhizoctonia. 
3 
'3 
w 
o 
> 
GO 
s 
"3 
o 
Eh 
Ph 
*"3 
"3 . 
Vigor. 
1 
C.c. 
11,250 
22, 500 
33,750 
1 
1 
2 
C.c. 
937 
1,875 
2,812 
107 
66 
126 
102 



2 
8 


38 
70 
7 
3 
58 
78 
7 
3 
98 
73 
11 
2 
96 

2 
2 
2 

3 
2 
2 
In. 
5 
4 
4-5 
4 
Healthy. 
2 
Do. 
3 
Do. 
(2) 
1 Saturated with cold water. 
2 One plant damped off. 
Table VI. — Record of temperatures in hot-water disinfection tests of soil in 8-inch 
pots and bench sections. 
[Treatments were with boiling water (at 98° C). Two series of time observations (in minutes) were made, 
as follows: Series A, time required to reach the temperature indicated; series B, time during which soil 
temperatures remained above the points indicated. Temperatures were ascertained by inserting stand- 
ard thermometers to a depth of 3 to 4 inches in the center of the pots and at two points in the bench 
section (No. 3).] 
Observation 
d 
d 
& 
o 
© 
Temperatures (° C). 
data. 
50 
55 
60 
64 
66 
70 
72 
75 
76 
77 
78 
79 
80 
81 
82 
83 
Time, series A : 
f 3,000 
| 4,000 
J33, 750 
f 3,000 
j 4,000 
J33, 750 
I'i 
ti 
| 1 
1 2 
1 3 
/ 1 
I 2 
4 
5 
4 
2.5 
5.5 
'8." 5 
6 
6 
5 
4 
6.5 
'"5 
7 
7 
6 
4.5 
7.5 
9 
7.5 
6.5 
5 
8 
6 
10 
8.5 
7 
6 
9 
9 
"9." 5 
10 
8 
6.5 
10 
10.5 
9 
7 
12.5 
8-inch pots. . 
{'] 
3" 
7.5 
"4" 
9.5 
7.5 
9 
Bench sec- 
7 
tion 1 
13 
Time, series B: 
33 
28 
33 
40 
38.5 
19 
19 
23 
27.5 
•>-. 5 
9 
"6." 5 
22 
20 
10 
5 
13 
9.5 
11 
14 
14 
4 
7 
10.5 
8 
57 
65.5 
63.5 
61.5 
48.5 
8-inch pots. . 

10.2 
80.5 
53" 
36.5 
41*5 
9 
3.5 
6.5 
Bench sec- 
tion 1 
1 
• 
1 
soil 
The application of hot water to the bench section (No. 3) was at the rate of 3,000 c. c. per 8-inch pot of 
SUMMARY. 
1. The root-knot nematode (Heterodera radicicola), Rhizoctonia 
species, and Pythium debaryanum can be eliminated from soil in 
4-inch pots by submersion for 5 minutes in water at 98° C. (208° F.). 
2. These organisms can also be killed in 8-inch pots by the appli- 
cation of 3,000 c. c. of water heated to 98° C. C208° F.). This treat- 
ment is the equivalent of an application of about 7 gallons per cubic 
foot of soil. 
3. These pathogenes are almost entirely destroyed in 8-inch pots 
by treatment with 2,000 c. c. of boiling water (5 gallons per cubic 
foot). 
