FUSARIA OF POTATOES 1 

 C. D. Sherbakoff 



INTRODUCTORY 



The purpose of this work has been to lay down a basis for the study 

 of the disease known as the fusarial wilt and dry rot of potatoes, Solanum 

 tuberosum. 



On the basis of previous work done by various mycologists and plant 

 pathologists on Fusaria of potatoes, it was evident, even before the 

 monographic work of Appel and Wollenweber (1910), that the potato 

 is a host of a number of different species of Fusarium. At the same time 

 the descriptions of these organisms were, almost without exception, so 

 confusing, and the organisms as a rule were apparently so variable, that 

 there was no sure way of identifying a Fusarium isolated from potato 

 with a previously described Fusarium even of the same host. Such a 

 state of affairs led Smith and Swingle (1904:50) to make a general state- 

 ment as follows: " Many specific names have been given to Fusaria 

 growing on the potato, and while some of these names may stand for 

 distinct forms, this is not at all certain. Most of these names undoubtedly 

 are synonyms, and for the purpose of this paper all are regarded as such." 



On the other hand, Lindau (1908) and others continued to believe 

 firmly that there were different Fusaria of potatoes, and that Fusarium 

 oxysporum as described by Smith and Swingle is nothing else than a 

 " Mischart." 



Whether more than one species of Fusarium occurs on this host and, 

 if more than one, on what basis they could be separated, was then the 

 question which in the opinion of the writer needed to be definitely settled 

 before any pathological work with these organisms could be properly 

 done. This involved the accumulation of as many different strains of 

 the Fusaria as was practicable, from all available sources, and their com- 

 parison in pure culture on various suitable media and under the same 

 conditions of growth. On this basis the work has been carried on since 

 the autumn of 1911. 



1 Presented to the Faculty of the Graduate School of Cornell University as a major thesis in partial 

 fulfillment of the requirements for the degree of doctor of philosophy. 



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