Feb. 3,1923 
Cotton-Wilt, a Seed-Borne Disease 
389 
no indication of disease were transferred to test tubes of com meal or 
potato agar, originally with the intention of using them for inoculation 
tests, but, as several of these seedlings developed signs of wilt, they were 
saved in later series for the purpose of observing possible development 
of signs of wilt infection. Nearly half of the total isolations of the wilt 
fungus were secured by this method (PI. 2, A). 
After the definite identification of some of the fungi isolated from the 
cotton seed as Fusarium vasinfectum, the remainder of the seed was 
saved for plating at intervals of about one month, for the purpose of 
determining the length of time the fungus may remain viable within the 
seed. 
The isolation series is given in Table I. 
Tabus I .—Isolations of Fusarium vasinfectum from cotton seed. 
Date isolated. 
Series. 
Number 
of seeds. 
Number 
of isola¬ 
tions of 
F. vasin¬ 
fectum. 
Viable 
infected 
seed . 1 
Viable 
seed not 
infected . 1 
Dead 
infected 
seed . 1 
Dead 
seed not 
infected . 1 
Sept. 27, 1921. 
Sept. 28, 1921. 
Oct. 6, 1921. 
Oct. 16, 1921. 
Oct. 25, 1921. 
Dec. 12, 1921. 
Jan. 17, 1922. 
Feb. 16, 1922. 
Mar. 14, 1922. 
Apr. 17, 1922. 
Sept. 27 to Oct. 16, 
1922. 
A. . 
X. . 
B. . 
C. .. 
D. . 
H.. 
K. 
J-. 
Y. . 
T.. 
F 2 
Total 
105 
119 
150 
150 
150 
95 
100 
200 
200 
200 
1,469 
46 
+ « 
68 
77 
no 
109 
5 ° 
35 
80 
82 
4i3 
14 
46 
35 
45 
42 
54 
116 
117 
458 
1 The isolation of the wilt fungus only is considered here in the terms “infected” and “not infected.” 
* The F series was isolated from what at first were apparently healthy seedlings from the series A, X, B, 
and C, after these had grown for some time on agar in test tubes. 
An examination of Table I will show that the percentage of isolations 
of Fusarium vasinfectum fell off rapidly after the third month. The fun¬ 
gus was recovered 39 times from 769 seeds plated within three months 
of the date of collecting, and only 7 times from 700 seeds plated from the 
fourth to the seventh month, the percentage of isolations falling from 
approximately 6 per cent in the first month to ]/ 2 per cent in the sixth 
and seventh months. The plating of April 17 exhausted the supply of 
selected seed. For the first six series of isolations, plump, viable-appear¬ 
ing seed was selected, which left a large percentage of light, immature 
seeds in the later series and may have affected the results to some extent, 
although there is no apparent reason why it should, unless the presence 
of the wilt fungus in the immature seed may have been more often 
masked by the presence of other fungi. 
