17 



Table 2. It should be mentioned that not only may species within a 

 genus differ widely (300, 330), but strains or geographical isolates of 

 the same species may respond differently (83a, 143). 



Surprisingly many fungi are able to grow, although usually only 

 slowly, at 0° or slightly less. Plants under snow may be infected by the 

 parasitic "snow molds" — Ty pint la spp., Fusarium nivale, and an un- 

 identified basidiomycete (32, 65, 242). Phacidium infestans, cause of 

 a disease of pines, is able to grow in culture at —3°, although its 

 optimum temperature is about 15° (232). 



A second ecological group of fungi tolerant of low temperature is 

 commonly associated with the spoilage of refrigerated foods. Fungi of 

 many different genera fall into this group and some, especially strains 

 of Cladosporium and Sporotrichum, grow at temperatures well below 

 zero, e.g., —5 to —8°. The literature on these forms is reviewed by 

 Berry and Magoon (19) and, more briefly, by Pehrson (232). Again, 

 although these fungi tolerate extremely low temperatures, their optima 

 are higher (122). 



Survival of spores and mycelium at temperatures too low for growth 

 is discussed briefly in Chapter 13. 



Most fungi are unable to grow at 35-40°C. There are, however, 

 two general types of exceptions to this rule. The first group is a 



