24 
N . C. Experiment Station 
TABLE VIII 
Per Cent of Anthracnose and Germination in Cotton Seed Which Has Been 
Subjected to Drying at 40-45° C. and Subsequent Heating at 60° C.* 
Exp. No. 
Lot No. 
Time of 
Preliminary 
Drying at 
40-45° C. 
Hours 
Time of 
Heating 
at 60° C. 
Hours 
Per Cent of Seeds 
Developing Diseased 
Seedlings 
Per Cent of Seed 
Which Germinated 
Treated 
Untreated 
Treated 
Untreated 
1 
1 
72 
48 
2 
86 
2 
72 
72 
0 
80 
3 
72 
96 
2 
82 
z 
1 
72 
Not heated 
14 
40 
96 
96 
2 
72 
24 
2 
40 
90 
96 
3 
72 
4,8 
4 
40 
92 
96 
3 
4 
1 
72 
72 
72 
24 
2 
4 
40 
86 
96 
96 
2 
72 
48 
2 
90 
A 
3 
72 
72 
2 
94 
1 
24 
72 
0 
0 
98 
98 
V 
1 
144 
Not heated 
4 
40 
92 
06 
2 
120 
48 
8 
40 
86 
96 
■crop ^Tn , crop w ^ sused a11 tests except Exp. 4 in which case seed was from the 1920 
■crop, in age the seed ranged from 10 months in Exp. 1 to 15 months in Exp. 3. 
When comparison of the percentages of diseased seedlings derived from 
treated and untreated seed is made, it is obvious that this treatment greatly 
i educes but does not entirely eliminate seed-borne infection. Forty per cent 
ot the seedlings from untreated seed developed anthracnose but not over 4 
per cent from the treated seed became diseased. The preliminary drying 
at 45° reduced the number of diseased seedlings to 14 per cent in 72 hours 
nnd to 4 per cent in 144 hours. Strangely, heating at 60° for 24 hours seems 
as effective as the 72 and 96 hour period. Apparently the fungus in or on 
a very small percentage of the seeds is much more resistant than in the 
lest of the seeds. Experiment 4 shows that a preliminary drying for as 
snort a time as 24 hours fully prepared the seed to endure 60° C. for 72 
hours. A number of tests not here tabulated indicate that as a result of 
ageing, the disease had completely- disappeared from the seed used in Ex¬ 
periment 4 by the time that experiment was made. 
When it was learned that a temperature of 60° C. was not sufficiently 
high to kill all seed-borne infection in a reasonable time, a number of 
experiments were made using a temperature of 70° C. As before, the seed 
were given a preliminary drying at 40-45° C. Seed of the 1919, 1920 and 
1921 crops, all heavily infected, were used in the experiments. Table IX 
sets forth the data pertaining to these tests. 
