6 MASS. EXPERIMENT STATION BULLETIN 350 



Table 2. -Temperatures at which Spores of Cladosporium fulvum Germinate 



Authority 



Temperature at which spores germinate 



Bewley (4) , 



Hasper (11) 32-33 



Makemson (13) 



Small (26, 27, 30) 



Williams (39) 



Newhall and Wilson (15) 



Alexander (2) 



Wollenweber (41) 



Gardner (10) 



Guba 



(32) winter weather from January 4 to May 1 at which a low temperature of 

 — 4° F. was reached did not affect the viability of the conidia. Judging from the 

 epidemic occurrence of the disease from year to year, it seems that in Massachu- 

 setts, winter weather conditions have no adverse influence upon the fungus. 

 Knowledge of the higher thermal death point would appear to have some practical 

 application since high temperatures were advised in England in an effort to control 

 the disease. Wright (42) and Thompson (35) advocated raising the greenhouse 

 temperature to 110°-120° F. every second day for a week, and it is further noted 



Figure 1. Relation of Temperature to Growth of Germ Tubes after 48 Hours Incubation 



