RESISTANCE TO TEMPERATURES 



10$ 



Fenicillium glaucum. Neither Gloeosporiwn fructigenum nor 



Rhizopus nigricans, however, grew at 0° C, although meager colo- 

 nies of these organisms developed at 4.5° C. Since so many decay- 

 inducing fungi are able to grow at or near 0° C, it is essential that 

 subzero conditions be provided for many readily perishable foods 

 that must be kept for months before they normally reach the con- 

 sumer. Consequently storage in dry ice has been employed effec- 

 tively to meet these conditions. 



8 



12 



16 20 24 28 



Temperature (degrees Centigrade) 



32 



36 



Fig. 5. Comparison under controlled conditions of temperatures favorable 



for the development of tobacco-root rot with those favorable for the growth 



of the causal fungus. Tobacco-root rot develops best at temperatures below 



those optimum for the pathogen. (After Jones.) 



Numerous species of fungi are able to survive subzero weather, 

 as their going into dormancy in fall and their reappearance in 

 spring indicate. The cold of winter may decimate the fungus 

 population, but it does not cause the extinction within a given area 

 of any considerable number of species. 



Buller and Cameron (1913) exposed the fructifications of 

 Schizophyllnm commune for several winter months to tempera- 

 tures that ranged between — 15° C and —40° C. After the fructi- 

 fications had been brought inside for a few hours, they resumed 

 casting their spores. Moreover, when fructifications that were 

 actively discharging spores were quickly frozen at — 3 1 ° C, they 

 still retained their viability. 



Bennett ( 193 1 ) subjected the vegetative and perithecial stages of 

 Gibberella saitbinettii to —20° C every third day for 45 days, per- 

 mitting the temperature at no time to reach zero. Afterwards the 



