624 
Journal of Agricultural Research 
Vol. XXXI, No. 7 
Ascospores germinate very readily in sterile water and nutrient 
broths throughout a wide range of temperatures (pi. 3 C, a , b, c , d ). 
Successful germination has been obtained with the strains of S. 
libertiana tested at temperatures as low as 3 to 4° C. (pi. 3, D,'a to g) 
and as high as 30 to 31°. Ascospores on the surface of a nutrient 
agar plate, however, failed to germinate when subjected to a temper¬ 
ature of 30 to 31° for a week. This indicates that the spores can not 
withstand the drying effect of this high temperature unless they are 
surrounded with moisture in great abundance. 
Although no temperature experiments were made with ascospores 
used as inoculum for infecting plants, it was of interest to the writer 
to find that the ascospores could withstand such low temperature. 
“ Shooting” ascospores of S. libertiana , caught upon a potato-dextrose 
agar plate which was placed immediately in a refrigerator, retained 
their vitality after being subjected to a temperature that fluctuated 
between 5° and —3° C. for 4J^ days. No growth was made the 
first day, and only slight growth was evident within the 4^-day 
period. However, after the plate was placed at room temperature 
for 3 days, the surface of the medium was completely covered with 
the fine, white, cottony mycelium characteristic of Sclerotinia. 
. GROWTH IN HOST TISSUES 
From a market point of view, it is of extreme importance to de¬ 
termine the temperature relations of Sclerotinia, and to determine 
whether there is any possibility of controlling decay by low tem¬ 
peratures. So far as the writer has been able to ascertain, the lower 
temperature limits of infection by Sclerotinia have never been de¬ 
termined. In order to obtain information along this line, several 
inoculation experiments have been carried out* in which various hosts 
were tested. 
Figure 3» presents in graph form the results of a typical experiment. 
Fresh bean pods of the Golden Wax variety were sterilized in mer¬ 
curic chloride (1 to 1,000) for three minutes, and thoroughly washed 
in sterile distilled water; each pod was then cut in half and placed in a 
large test tube containing 3 c.c. of sterile water. The freshly cut ends 
of these pods were inoculated with young mycelium from potato- 
dextrose agar plate cultures. After inoculation all cultures were 
placed immediately in cold storage at 0°. At the end of 26 days the 
cultures were taken out and examined, both for penetration of the 
host tissues and aerial growth of the fungus. In each case it was 
found that the depth of penetration of the fungus was somewhat- 
greater than the corresponding height of the aerial growth. S.‘ 
libertiana penetrated along the long axis of the pod a distance of 
6 mm., while S. minor and S. intermedia penetrated 24 mm. and 37 
mm., respectively. The rate of growth as here shown is somewhat 
slower than that of the same fungi on potato-dextrose agar. How¬ 
ever, the same relative positions are held as regards differences in 
growth rate among the three species. 
This experiment taken together with others of similar nature, 
seems to show conclusively that it is possible for vegetables to become 
infected with Sclerotinia and for a slow decay to result, even though 
the product is held at 0° C. In other experiments in which beans, 
peas, and carrots were used in inoculations at 3° to 4°, decay took 
