690 
Journal of Agricultural Research 
Vol. XXVIII, No. 7 
Table IV .—Relation of soil moisture to development of Fusarium cepae 
Original 
moisture 
content 
(percentage of 
dry weight) 
Moisture con¬ 
tent of surface 
2 inches at 
end of exper¬ 
iment 
Approximat e 
per cent of 
water-hold¬ 
ing capacity 
Number of 
plants in¬ 
oculated 
Days elapsing 
before all 
plants had 
wilted 
Number of 
control 
plants 
Number of 
checks 
wilting 
10.5 
9.5 
26 
12 
14 
4 
0 
21 
25 
50 
«12 
20 
4 
0 
31 
33 
85 
12 
14 
4 
0& 
37 
37.5 
100 
12 
15 
4 
0& 
. 
° One plant had not wilted at end of experiment. 
& One bulb rotted completely without sprouting. 
The next experiment consisted essentially of a repetition of the soil temperature 
studies with the exception that two complete series were included—one in soil 
adjusted to 30 per cent and the other to 75 per cent of its water-holding capacity. 
The results given in Table V show again the influence of temperature on the 
development of the disease. 
The plants in the high moisture series sprouted and grew much more rapidly 
than those in the lower moisture cans, and attained a much greater final growth. 
The same was true with the check plants in the high-temperature tanks, as com¬ 
pared with the lower ones, but the greatest final growth took place in the high- 
moisture cans in the 19° C. tank. The first evidence of the effect of the fungus 
on the plants appeared simultaneously in the high and low moisture cans in 
the 26° tank on the eighth day. A day later the inoculated plants in the 
30° and 26° tanks began to wilt, followed two days later by one in the 19° 
tank. Although the wilt appeared in the 19° and 22° tanks shortly after it 
appeared at the higher temperatures, its progress was much slower in the former. 
This agrees with former temperature experiments. At 12° the disease did 
not appear in either lot after 35 days, showing this to be below the minimum 
temperature for its development. The results again show that there is. no 
appreciable difference in the rapidity of Fusarium rot under widely different 
soil-moisture conditions. It is to be noted, however, that in all these experiments 
the fungus was injected into the tissue of the bulb at the beginning. Therefore 
the results should not be interpreted as necessarily indicating the effect of soil 
moisture upon initial infection but rather upon the progress of the disease after 
infection. 
Table V .—Effect of soil-moisture content upon the progress of Fusarium cepae 
at various soil temperatures 
Days elapsing before 
Days elapsing before 
first plant wilted 
all plants wilted 
Temper¬ 
ature 
Thirty 
per cent 
water¬ 
holding 
capacity c 
Seventy- 
five per 
cent 
water¬ 
holding 
capacity d 
Thirty 
per cent 
water¬ 
holding 
capacity c 
Seventy- 
five per 
cent 
water¬ 
holding 
capacity d 
Condition 
of 
controls 
°a 
30 
9 
9 
11 
12 
Healthy. 
26 
8 
8 
10 
10 
Do. 
22 
9 
9 
17 
16 
Do. 
19 
11 
11 
19 
19 
Do. 
12 
(*) 
C) 
<■) 
( a ) 
i 
( b ) 
• None of the plants showed signs of wilt at 45 days. 
h One plant attacked by Aspergillus and Penicillium but inoculated plants not affected. 
«11.1 per cent of the dry weight. 
* 27.8 per cent of the dry weight. 
