SOIL DISINFECTION WITH HOT WATER. 7 
to 4 to 5 inches in height, and all were vigorous and healthy in ap- 
pearance. Differences existing at the end of the experiment in 
number, size, and general appearance of the plants in pots receiving 
the different treatments are shown in Plate II, figure 2. Compare 
with Plate II, figure 1, which shows some of the same pots at a very 
early stage in the experiment. 
4. The application of 3,000 c. c. of boiling water per 8-inch pot 
(180 cubic inches of soil) gave complete control of both nematodes 
and soil fungi in both sets of pots. Applications of 1,000 c. c. and 
2,000 c. c. gave partial control of the pathogenes. An average of 
20 and 13 per cent, respectively, of the plants in these pots showed 
mild nematode infection, as compared with 83 per cent of nematode 
infection in the check pots, most of which was severe. In two of 
the six pots receiving the 2,000 c. c. treatment no Rhizoctonia infec- 
tion occurred, while plants in the remaining pots showed slight root 
discolor ations. Nearly all plants, however, which received the 1,000 
c. c. treatment showed root discolor ations. The roots of the plants 
in the untreated check pots were badly discolored, many being 
entirely destroyed by the fungous parasites. A comparison of the 
appearance of the roots from plants grown in treated and untreated 
soil is shown in Plate III. 
Table II. — Soil-disinfection tests with tomato and lettuce plants grown in shallow 
bench sections, with hot-water treatment, in February and March, 1918. 
[The bench, sections were 5 to 6 inches deep and filled with nematode and fungus-infested soil thoroughly 
mixed by sifting.] 
Application 
of boil- 
ing water (at 
98 s C). 
Results observed on Mar. 8, 1918 (end of experiment). 
Pvthium 
Kind of plants 
and bench 
g 
's 
ft 
Nematode infesta- 
tion of roots. 
and Rhi- 
zoctonia 
infection 
Plant notes. 
section No. 
w 
,a 
of roots. 
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>> 
C/3 
o 
a 
3 
PI 
o 
t-l 
a 
a 
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o 
03 
u 
ft 
60 
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ft 
ft 
ft 
S 
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of 
si 
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£ 
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a 
o 
pi 
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B 
03 
ad 
2 
a 
o 
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V 
bp 
m 
H 
y A 
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H 
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3 
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ft 
£ 
ft 
w 
Tomato: 
Inches. 
C.c. 
C.c. 
No. 
In. 
1 
26 by 18... 
26 by 16... 
24 by 18... 
24 by 16... 
8,500 
13,500 
17, 000 
1 
750 
s 
108 

o 
43 
43 
40 
66 
61 
6 
Hg. 
Hg. 
Hg. 
Sy.8 
2 
? 
1,000 

94 

n 
98 
?8 
30 


6 
3 
9 
1,500 

204 
n 
4 
10 
14 
7 
3 
14 
7 
4 check 2. . 
15 
75 
15 
21 
18 
54 
72 
75 
100 
4 
Lettuce: 
j 
26 by 18... 
26 by 16... 
24 by 18... 
24 by 16... 
8,500 
13,500 
1 
750 
6^ 
178 

?8 
43 
71 
40 
178 
100 
2i 
3 
Y. 
2 
? 
1,000 
<i 
197 


9 1 
91 
11 
32 
16 
Hg. 
Hg. 
Sg.* 
3 
17,000 
?, 
1,500 
n 
210 


9 
? 
1 


5 
4 check 2 . . 
25 
32 
6 
12 
2 
20 
64 
32 
100 
2 
' 
1 Abbreviations used: Hg= Healthy green, Sg= Sickly green, Sy= Stunted yellow. 
2 Saturated with cold water. 3 p or stand. • * Stand 25 per cent. 
From the details of the bench experiments, which are given in 
Table II, the results are here briefly stated. 
