16 



CULTIVATION AND GROWTH 



20 25 30 



Optimum temperature, °C 



35 



40 



Figure 6. The optimum temperatures for growth of plant pathogenic fungi. Com- 

 piled by Dr. C. E. Yarwood from Togashi (307). 



and warmer temperate regions of the earth (84). Subtropical strains of 

 a species may have a higher temperature optimum than strains from 

 temperate regions (38). The distribution of Phymatotrichum omni- 

 vorum is determined by winter soil temperature (90). The few marine 

 fungi studied so far have temperature optima for growth that are some- 

 what higher than the temperature of the sea (8). The occurrence and 

 dominance of fungi in decomposing plant materials are largely deter- 

 mined by temperature (150, 223). 



Dermatophytic fungi grow best in culture at 25-35°C, i.e., below the 

 host body temperature (284); fungi causing systemic mycoses grow well 

 at 37° but optima have not been reported. It is significant that Asper- 

 gillus fumigatus, a thermotolerant species, can cause disease in warm- 

 blooded animals. 



Some examples of high and low temperature optima are collected in 



