10 
N. C. Experiment Station 
neighboring fields. If, in such a case, one is forced to select seed from 
only a part of the plants because of the presence of disease on the others, 
the quantity of seed available for the multiplication plots is greatly re¬ 
duced. Seedsmen and breeders who have had this experience appreciate 
the desirability of a dependable method of treatment for killing all seed- 
borne infection without reducing the capacity of the treated seed for germi¬ 
nation. Moreover, this would make possible the introduction with safety 
of seed of desirable lineage whose disease record is unknown. 
B. Surface disinfection. Treatment of diseased cotton seed with such 
surface disinfectants as solutions of copper sulphate, mercuric chloride 
and formaldehyde is difficult because of the fuzz on the surface of the 
seed. These solutions do not readily enter the interstices of the fuzz; 
hence a large portion of the surface borne infection escapes their ac¬ 
tion 4 , 10 , 33 . Moreover, such disinfectants cannot reach the elements of the 
fungus carried within the embryonic tissues without seriously damaging 
the embryo itself. 
Delinting with sulphuric acid has also been used as a measure of control 
of cotton anthracnose. This solution dissolves not only the lint, but also 
any spores and mycelium that may be carried in it. Such treatment 
greatly diminishes the load of infective material carried by the seed and 
decreases the incidence of the disease in the field. However, it does not 
render infected seed completely free from disease since delinting does not 
reach mycelium and spores carried within the seed. This fact is clearly 
demonstrated by tests made by the writer in which highly diseased seeds 
were delinted with sulphuric acid and compared with nondelinted seeds 
in order to determine the relative number of seeds in which the fungus 
had penetrated beyond the reach of this powerful disinfectant. Each 
test comprised 50 treated and 50 untreated seeds selected to exclude any 
which appared to be nonviable. The seeds were kept in concentrated 
sulphuric acid for periods of 10, 20 and 30 minutes. During this time they 
were repeatedly stirred to insure good contact with this acid. At the end 
of the periods indicated the seeds were washed in several changes of 
tap water to remove the acid and finally placed on sterile, moist blotting 
paper in test tubes to germinate. The result of these tests are presented 
in Table I. 
TABLE I 
Percentage of Anthracnose Which Developed on Seedlings From Corresponding 
Lots of Delinted and Undelinted Cotton Seed. 
Lot No. 
Minutes in 
Con. 
H 2 SO i 
Days in 
Germinator 
Per Cent of Seed Which 
Developed Diseased 
Seedlings 
Per Cent of 
Germination 
Year When 
Grown 
Treated 
Check 
Treated 
Check 
1 
20 
8 
6 
66 
64 
98 
1919 
2 
10 
8 
12 
34 
82 
98 
1919 
3 
10 
8 
10 
34 
70 
98 
1919 
4 
30 
14 
16 
92 
1922 
