Dec., 1923] 
SHERWOOD — FUSARIUM WILT OF TOMATO 
543 
were figured. At the end of the experiment, by which time the plants were 
getting too large for good growth in the flats, all plants still standing were 
carefully removed from the soil and examined for wilt infection. Great 
care was used in this examination, and all plants showing the slightest signs 
of vascular discoloration were classed as infected. The results of the 
experiment are shown in table 1. 
Table i. Influence of Soil Reaction on the Development of Fusarium Wilt of Tomato Seed¬ 
lings 
Type of Soil 
Number of 
Flat 
Reaction of 
Soil, pH 
No. Plants 
Died in 
Six Weeks 
No Plants 
not Wilted 
but Found 
Infected 
No. Plants 
in Flat 
Percent¬ 
age of 
Plants Dis¬ 
eased 
Percent¬ 
age of 
Plants 
Dead 
Sandy loam. 
I 
6.2 
17 
9 
53 
2 
6.2 
23 
8 
50 
55-3 
38.8 
U U 
3 
6.6 
8 
10 
50 
47.5 
28.2 
u 11 
4 
6.6 
20 
9 
49 
“ . 
5 
6.8 
10 
9 
50 
u u 
6 
6.8 
12 
10 
50 
41.0 
22.0 
Silt loam. 
1 
5-8 
24 
12 
47 
76.6 
51.0 
u u 
2 
6.0 
7 
8 
43 
34-9 
16.3 
u u 
3 
6.2 
6 
12 
50 
“ “ . 
4 
6.2 
7 
5 
50 
30.0 
13.0 
u n 
5 
6,4 
5 
7 
50 
24.0 
10.0 
At the close of the experiment soil samples were taken in order to deter¬ 
mine the reaction, but the determinations were not made until two weeks 
later. It should be noted that a drop of 1.0 pH means that the acidity 
of the medium is increased ten times. A drop of 0.3 pH approximately 
doubles the acidity. The differences in reaction are thus greater than the 
figures in table 1 might seem to indicate. Among several of these soils no 
difference could be detected; consequently the flats containing soil of the 
same reaction are grouped together in the table. As might be expected, 
some variations from uniformly consistent results occurred even in soils 
having the same reaction. There is shown, however, a distinct gradation 
in the amount of wilt developing from the more acid down to the less acid 
soils. 
Experiment 2 
In preparation for this experiment the soils in all the flats, except num¬ 
bers 1 A and 1, were treated with increasing quantities of pure calcium 
carbonate. Beginning with flats no. 2 the quantities added were 7.5 grams, 
15 grams, 30 grams, 60 grams, and 90 grams, respectively. Figured on the 
basis of 2,000,000 pounds as the weight of one acre of soil six and two 
thirds inches deep, these amounts represent the application of approxi¬ 
mately one, two, four, eight, and twelve tons per acre. After thorough 
admixing was accomplished, the flats of soil were steamed for six hours at a 
pressure of about four pounds. After they had been allowed to stand for 
three days, the soils were reworked and samples taken for a determination 
