44 HISTORY OF PHYTOPATHOLOGY 



other diseases equally common though less strikingly 

 destructive. This was especially true of the rusts and 

 smuts of cereals. 



Thus the middle of the nineteenth century saw the 

 beginning of a new era in the science of phytopathology. 

 In the establishment of the pathogenic nature of fungi, 

 the autogenetic theory of disease in plants received a 

 staggering blow. The day of the autogenetists had 

 passed, and for the next half-century or more a new 

 school, the pathogenetists, and the etiologic phases of 

 phytopathology were to dominate the science. 



The era falls naturally into two periods of approxi- 

 mately a quarter century each, the Kiihnian and the Mil- 

 lardetian. The first of these is characterized by an al- 

 most complete devotion to the study of the causal rela- 

 tions of fungi to the diseases with which they are found 

 associated; the second period saw a marvelous develop- 

 ment and general application of methods of disease 

 control. Together they constitute an era unparalleled 

 in the history of plant pathology. 



THE KUHNIAN PERIOD 



This period (1853-83) will always stand out as one of 

 the greatest in the history of plant pathology. It is 

 characterized chiefly by the discoveries which have 

 firmly established the causal nature of fungi associated 

 with plant diseases. As fungi are now generally recog- 

 nized to be responsible for most of our plant diseases, the 

 importance of the pioneer work of this period cannot be 

 overestimated. 



The phytopathologists of this period were powerfully 

 influenced in their thought and theories by the works of 



