466 
Journal of Agricultural Research 
Vol. VIII, No. 12 
Table III .—Results of a field experiment to determine the agency of insects in the dis¬ 
semination of angular leaf spot 
Row. 
Plot I. 
Plot 6. 
Plot 
14. 
Plot 8. 
Plot 2. 
Plot 
10. 
Plot 9. 
Plot 4. 
Plot 5. 
Plot 
12. 
Plot 18. 
Plants. 
Plants diseased. 
Plants. 
r Plants diseased. 
Plants. 
Plants diseased. 
Plants. 
Plants diseased. 
Plants. 
| Plants diseased. ] 
Plants. 
Plants diseased. | 
Plants. 
Plants diseased. | 
Plants. 
Plants diseased. | 
Plants. 
Plants diseased. | 
Plants. 
Plants diseased. | 
Plants. 
| Plants diseased. | 
41 
1 
49 
0 
35 
0 
46 
1 
80 
0 
51 
4 
25 
0 
19 
0 
69 
0 
52 
1 
46 
0 
35 
0 
So 
0 
4 i 
0 
38 
1 
78 
0 
54 
2 
26 
0 
21 
0 
64 
0 
47 
0 
31 
0 
53 
«;6 
83 
0 
4... 
21 
48 
38 
a8 
37 
5. 
21 
61 
37 
0 
18 
6. 
0 
0 
65 
44 
58 
15 
6 
1 
52 
0 
'll 
44 
47 
36 
Total. 
154 
2 
378 
5 
279 
2 
329 
2 
486 
0 
336 
9 
131 
0 
97 
0 
133 
0 
177 
1 
170 
0 
Considering the irregular distribution of the diseased plants in plots 
i, 6, 14, 8, and 2, little evidence of insect activity is noted; and this fact, 
together with the higher percentage of diseased plants in plot 9, which 
was credited with high seedling infection (Table I), might lead one to 
believe this disease present to be more likely due to seed infection or 
spread from such plants. 
DISSEMINATION BY WIND DURING RAINEALE 
An extensive inoculation experiment was arranged in one of the college 
cotton fields to demonstrate beyond all doubt the pathogenicity of the 
organism which preliminary inoculations indicated was Bacterium 
malvacearum . This field was located on a plateau overlooking a valley 
2 miles wide sloping from east to west, with no higher hills near by. The 
row chosen for the experiment was parallel to a roadway and about 20 
rows from it (80 feet). The inoculations were made on May 26, one per¬ 
son applying the bacteria from agar-slant cultures to the underside of 
two or three leaves of each plant by means of a sterile glass rod. One 
tube culture and one rod were used as far as the culture served, when 
another culture and rod were used. The bacteria were gently spread 
over the underside of the leaf with the fingers by a second person, using 
rubber gloves to facilitate sterilization after each culture. The success of 
the experiment was noted on June 3 (eight days later), though a complete 
record was not taken until June 5, when an examination showed that 
none of the control plants were diseased and that all those inoculated 
were diseased except two. These also showed infection shortly after¬ 
wards. 
A record was taken on June 5 of the number of leaves infected and 
uninfected. Comparison with a similar record taken on June 15 showed 
an increase from 2 to 10 leaves per plant, usually 3 to 6, and a similar 
