546 
AMERICAN JOURNAL OF BOTANY 
[Vol. 10, 
numbered i, 2, 3, 4, and 5 respectively. The old flat no. 2 was discarded. 
The soil in the old flat no. 4 was treated with 60 grams of calcium carbonate, 
50 grams of slaked calcium oxide, and 10 grams of magnesium sulphate. 
This flat was added to the series and numbered 6. 
Silt-loam series. Flats no. 1^4, no. 1, no. 3, and no. 5 were renumbered 
1, 2, 3, and 4 respectively. The soil in the old flat no. 2 was treated with 70 
grams of calcium carbonate, 50 grams of slaked calcium oxide, and 10 grams 
of magnesium sulphate. The soil in the old flat no. 4 was treated with 60 
grams of calcium carbonate, and 10 grams of magnesium sulphate. These 
flats were added to the series and numbered 5 and 6 respectively. 
The soil in all the flats was given an application of a 6-16-8 fertilizer 
(composed of calcium nitrate, potassium chloride, and monocalcium phos¬ 
phate) at the rate of about 600 pounds per acre. The soils were not steri¬ 
lized, but were reinoculated and planted as before. The results obtained 
are given in table 4. 
Table 4. Influence of Soil Reaction on the Development of Fusarium 
Wilt of Tomato Seedlings 
Type of Soil 
Number of 
Flat 
Reaction of 
Soil, pH 
No. Plants 
Died in 
Five 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. 
ti it 
I 
54 
28 
20 
50 
96 
56 
2 
5-8 
15 
15 
50 
60 
30 
l l tt 
3 
6.4 
II 
8 
50 
38 
22 
“ “ . 
4 
6.8 
12 
9 
50 
42 
24 
a it 
5 
7.2 
I 
5 
50 
12 
2 
tt it 
6 . 
8.2 
3 
8 
50 
22 
6 
Silt loam. 
1 * 
5-6 
39 
5 
50 
88 
78 
“ “ 
2 
5-8 
28 
13 
50 
82 
56 
it it 
3 
6.0 
4 
12 
50 
32 
8 
it it 
4 
6.4 
13 
20 
50 
66 
26 
5 
6.8 
9 
13 
50 
44 
18 
6 
7.2 
5 
16 
50 
42 
10 
The development of the disease was much slower in this experiment than 
in those preceding, in which the soil was sterilized before inoculation. The 
first symptoms did not appear until three weeks after planting. In many 
cases wilting of only a portion of the plant was observed for two or three 
days before general wilting occurred. Preliminary leaf yellowing was also 
noticed in a number of cases. The plants grew more rapidly than in the 
other experiments, though considerable cloudy weather prevailed. On 
clear days the temperature fluctuated in a manner similar to that previously 
described. 
As in the preceding experiments there was a considerable reduction in 
the number of diseased plants occurring at the alkaline end of each series. 
The plants produced in the sandy soil at pH 8.2 were hardly as large as those 
produced at 7.2, but they presented a very thrifty appearance. In general 
