TEMPERATURE 407 



9. TEMPERATURE AND GERMINATION 



The so-called cardinal temperatures for spore germination — the 

 minimum, optimum, and maximum — have been determined for very 

 many fungi; most data on plant pathogens reported prior to 1936 are 

 summarized by Togashi (285), other results by Wolf and Wolf (303). 

 The student is immediately struck by the frequent and pronounced 

 disagreements in this literature; some of these are probably inherent 

 in the nature of the material, whereas others are traceable to inadequate 

 methods of study. 



Some examples of reported cardinal temperatures are shown in Table 

 3. The total range of temperatures permitting at least some germina- 



Table 3. Cardinal Temperatures of Spore Germination 



Minimum, Optimum, Maximum, 



tion varies in these data from 13 centigrade degrees, in Phoma apiicola, 

 to 40, in Rhizopus chinensis and Magnusia nitida. Optima range from 

 a low of 9°C in Peronospora effusa to a high of 43-45° in Rhizopus 

 chinensis. In general, it appears from these and other data, and is to be 

 expected on theoretical grounds, that fungi with a high optimum have 

 a broader total range than those with a low optimum; that is, fungi 



