Dec. io, 1913 
Foot-Rot of the Sweet Potato 
261 
Table I .—Summary of results of inoculations with Plenodomus destruens . 
Organ¬ 
ism 
No. 
Host. 
Place of 
inocula¬ 
tion. 
Method of inocula¬ 
tion. 
Number— 
Num¬ 
ber of 
checks 
in¬ 
fected. 
Ex¬ 
peri¬ 
ment 
No. 1 2 * * * * * * * 10 
In¬ 
ocu¬ 
lated. 
In¬ 
fect¬ 
ed. 
Checks. 
100... 
Ipom 0 e a 
Pot omac 
By inserting spores 
IO 
IO 
IO 
0 
1 
batatas. 
Flats. 
and hyphae into 
the lower part of 
the stem. 
_..do. 
Green- 
.do. .. 
8 
house. 
.. .do. 
...do. 
.do..... 
IO 
6 
...do. 
.do. 
6 
...do. 
.. .do. 
.do... 
8 
6 
6 
Ipom 0 e a 
.. .do. 
.do... 
7 
purpurea. 
Ipom 0 e a 
.. do. 
.do. 
0 
hedera- 
cea. 
101... 
Ipom 0 e a 
.. .do. 
.do. 
5 
3 
5 
0 
13 
coccinea. 
.. .do. 
.do. 
12 
.. .do. 
.do. 
8 
s 
6 
18 
.. .do. 
.. .do.. 
.do. 
10 
9 
7 
no... 
...do. 
...do. 
.do. 
6 
5 
5 
0 
20 
...do. 
...do. 
By spraying foliage 
IO 
0 
6 
0 
2 4 
with spores sus- 
pended in water. 
.. do. 
. do... 
.do...... 
6 
6 
8 
do. 
do. 
.do. 
6 
6 
101... 
.. .do. 
...do. 
By smearing coni- 
IO 
7 
6 
0 
5 
dia on lower part 
of stem. 
IOI... 
...do. 
.. .do. 
By pouring spores 
IO 
7 
6 
0 
6 
in water around 
the plant. 
101... 
Ipomoea 
...do. 
By inserting 
7 
7 
6 
0 
14 
batatas. 
hyphae into the 
lower part of stem. 
.. .do. 
...do. 
By inserting spores 
6 
6 
0 
15 
and hyphae into 
the node of vine 
several feet from 
the hill. 
108 , 
.do. 
.. .do. 
.do. 
5 
5 
0 
16 
IOI.,. 
Storage 
Labora- 
By inserting spores 
8 
0 
4 
0 
21 
sweet 
tory. 
and hyphae into 
p 0 t a - 
the end of potato. 
toes. 
108... 
.. .do. 
.. .do. 
.do. 
6 
6 
4 
0 
22 
1 For more complete data, the reader is referred to the experiments in the preceding pages corresponding 
to the numbers of this column. 
2 Experiments Nos. 4 to 7, inclusive, are combined in the body of the text, p. 258. 
Discussion of Inoculation Experiments 
Twenty-two sets of inoculations have been made with Plenodomus 
destruens , 17 of which were on sweet-potato plants. Eighty-four sweet- 
potato plants in nine different sets were inoculated by wounding the 
lower part of the stem and inserting spores and hyphae. Seventy-eight 
died of the disease. Seven plants were wounded in a similar manner 
and inoculated with hyphae only, and all became infected. Eleven vines 
in two sets were inoculated at the node several feet from the hill and io 
became diseased. Spores and hyphae were smeared on the lower part 
of the stems of io plants, care being taken to cause no wounds, and 7 
became diseased. Spores suspended in sterile water were poured about 
10 plants, and 7 died from the organism. The foliage of 26 plants in 
