EXPULSION OF ASCOSPORES 
Under artificial conditions in the laboratory expulsion of ascospores 
is entirely inhibited at low temperatures. With rise in temperature 
expulsion begins and activity of this process increases until finally 
expulsion of spores becomes abundant at temperatures ranging from 
about 68° to 80° F. At higher temperatures there is a gradual cessation 
of activity until at body temperature it is reduced to practically nil. 
Table II 
Summary of Tests on Effect of Temperature on Ascospore Expulsion 
No. of Traps Used 
No. of Days Tested 
Temperature F. 
Total No. of Spots 
Recorded 
Av. No. of Active 
Ostioles per Trap 
per Day 
21 
23 
13 
13 
38.6 
72.5 
0 
14424 
0 
48.2 
20 
19 
14 
14 
53.8 
72 
408 
6,627 
1.4 
24.9 
12 
12 
10 
10 
56.25 
70.8 
1,503 
12,969 
12.5 
108 
12 
12 
17 
17 
62.5 
72.8 
3.609 
16,871 
17.7 
82.7 
12 
12 
9 
9 
79 
72.2 
9,125 
8,950 
84-5 
82.8 
12 
12 
TI 
II 
84.6 
72.2 
4,232 
9,664 
32.06 
73-2 
12 
12 
7 
7 
90.8 
72.5 
462 
8,112 
5-5 
96.5 
12 
12 
15 
15 
98.4 
70-3 
74 
11,643 
0.4 
64.6 
It is interesting to note that there is a somewhat parallel relation 
between temperatures favorable for growth of the blight fungus and 
temperatures favorable for ascospore expulsion. The minimum, 
optimum and maximum temperatures for growth as given by Shear 
and Stevens (19) are as follows: 
Centigrade Fahrenheit 
Minimum 8-9 46-48 
Optimum 18-28 64-82 
Maximum 35 95 
