Chapter 18 

 MYCOLOGY IN RELATION TO PLANT PATHOLOGY 



Plant materials constitute the substrate on which nearly all 

 fungi thrive in their natural habitats. Relatively few utilize ani- 

 mals or animal tissues as substrates of first choice. Furthermore 

 many fungi, whether saprogenic or pathogenic, are quite closely 

 restricted to a particular plant species. The fundamental reasons 

 for these idiosyncrasies in the choice of food are not without sig- 

 nificance, but they remain quite unknown beyond the point that 

 there is a correlation between the enzyme-producing abilities of 

 each fungus and the kind of substrate on which it grows. 



The idea that all fungi are either parasitic or saprophytic has 

 had far-reaching consequences. It has had a deleterious effect 

 primarily on understanding the activities of fungi and secondar- 

 ily on appreciating the intimate interdependence of mycology 

 and plant pathology. It is not uncommon for a plant pathologist 

 to remark that parasitic fungi are of interest to him but that 

 saprophytic species are of no concern. He chooses to entrust 

 saprophytic species to the tender care of a mycologist! In so do- 

 ing he may overlook the fact that a particular species may have 

 both a parasitic and a saprophytic phase. Perhaps the terms para- 

 sitic and saprophytic have outlived a measure of their usefulness. 



A4uch information regarding the natural habitats of fungi has 

 come from studies, not of saprogenic species, but of pathogenic 

 ones and has therefore been contributed by plant pathologists. In 

 so far as such studies have emphasized the disease aspect, including 

 disease prevention and control, they properly constitute the sub- 

 ject matter of phytopathology. On the other hand, in so far as 

 such studies pertain to the etiologic agent itself, they belong to 

 mycology. The two fields are therefore closely interrelated, as 

 may be brought out by consideration of their parallel develop- 

 ment, but they have grown to be quite distinct. In fact, some 

 workers regard mycology as the parent science and phytopathol- 



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