Chapter 5 

 EFFECTS OF TEMPERATURE ON FUNGI 



Temperature is one of the most important environmental factors 

 affecting the metabolic activities of fungi. Since this fact is o-en- 

 erally appreciated, manv workers have concerned themselves with 

 problems involving the influence of temperature upon selected 

 species of fungi. These studies have dealt with temperature as a 

 factor in spore germination, mycelial growth, and reproduction 

 of the chosen organisms; with determinations of their cardinal 

 temperatures, temperature coefficients, and lethal temperatures; 

 with attempts to correlate temperatures that are favorable or in- 

 hibitorv to infection and the subsequent development of disease 

 or decav with those that are favorable or inhibitory to the Growth 

 of the pathogens; and with attempts to establish a rational basis 

 to account for the geographical distribution and seasonal incidence 

 of fungi. In the aggregate the reports of these studies contain a 

 large volume of data together with varied interpretations of them. 

 In the account that follows an attempt has been made to select 

 from these numerous reports representative materials that will 

 aid in evaluating the effects of temperature on fungi. 



It does not seem to be possible completely to isolate tempera- 

 ture as an environmental factor in studies with fungi. Such non- 

 temperature factors as relative humidity, rate of accumulation and 

 concentration of staling products and other by-products, char- 

 acter of the substrate, initial reaction and rate of change of re- 

 action of the medium, and aeration of the medium, as well as 

 factors internal to the fungus, such as strain differences and a^e 

 of the mycelium, exert an influence, whether the fungus is being 

 grown on artificial media or on the natural substrate. 



Furthermore in experimental conditions temperatures are either 

 maintained continuously or else fluctuate to only a small decree, 

 whereas in nature they vary continually. Whether all metabolic 

 activities can be maintained at a constant optimal level over indefi- 



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