Treatment of Cotton Seed 
17 
Except where otherwise specified, all germinations to determine the percent- 
age of seeds carrying viable elements of the anthracnose fungus have been 
made by the method recommended by Barre. 13 Small squares of blotting 
paper, were loosely placed in test tubes to make a column about 3-4 inch deep. 
This was moistened with tap water and the tubes were plugged and auto¬ 
claved at 15 pounds for 20 minutes. By use of long, sterile forceps, the seeds 
were placed one in each tube. The forceps were flamed after handling each 
seed as a precaution aganist carrying inoculum from seed to seed and thus 
increasing the percentage of infected seedlings. During the time required 
for each test the tubes containing the germinating seeds were kept in a 
covered, galvanized iron box containing an open vessel of water to prevent 
excessive drying while the seeds were sprouting. 
The first records were usually taken after the seeds had been in the germi- 
nator 6 to 8 days. The ungerminated seeds and healthy seedlings were re¬ 
turned to the germinator for another period of 5 to 7 days after which the 
percentages of disease and germination were again recorded. Often the 
tubes were put back, and records taken after a third period, thus extending 
the time in the germinator to 20 or more days. Usually, germination is 
complete and the maximum of disease has developed by the 15tli day. A 
microscopic examination of each diseased seedling was made in order to 
ascertain the cause of its death. In addition to the anthracnose organism, 
other fungi, especially Fusarium, Macrosporium and bacteria often attack 
the seedlings. 
EXPERIMENTAL 
As a preliminary study, it seemed desirable at the outset to determine, as 
nearly as possible the temperatures most favorable for germination of 
cotton seed, for growth of the anthracnose fungus and for development of 
the disease on the seedlings growing in test tubes. Accordingly, experiments 
were planned to test the effect of temperature on these processes. 
EFFECT OF TEMPERATURE ON GROWTH OF GLOMERELLA GOSSYPII 
Equal quantities of Czapek’s nutrient solution 27 solidified with 1.5 per cent 
agar and adjusted to a reaction of pH 7.2 were poured in petri dishes of 
uniform diameter. After the agar had solidified the dishes were inoculated 
at the center with, a loopful of a suspension of conidia in sterile water. 
Three of these cultures were then placed in each of four ovens which were 
adjusted to maintain temperatures of 21, 26, 30 and 34.5° C. Growth at the 
different temperatures was measured comparatively by determining the 
diameter of the colony at stated periods and by estimating the relative densi¬ 
ties of the colonies formed and the abundance of the conidia produced. Cliaud- 
huri 15 working with Verticillium ablo-atrum has shown that, while colony 
diameter is untrustworthy as a measure of the actual production of fungus 
material, it is satisfactory as a method of studying the relation of different 
temperatures to rate of growth in a medium of uniform composition and 
thickness. 
