STUDIES ON THE PHYSIOLOGY OF 



IJV 

 YOSHIHIKO TOCHINAI 



m n -^ m 



Introduction 



There arc three species of fungus as the causal fungi of the flax-wilt 

 disease, Asterocystis radicis De Wild, Fusarium Uni Bolley and Collectotri- 

 cnm linicobim Pethybridge et Lafferty. The most general and destructive' 

 wilt disease is 'caused b}' Fusariusn lini Bolley. 



The flax-wilt disease caused by Fusarium has become an important 

 problem in Japan and America. In Europe, crop rotation has been practised 

 habitually for flax cultivation for centuries, and as a consequence the flax- 

 wilt disease did not present so virulent a form as to attract the attention of 

 farmers and phytopathologists. But in Japan and America, where farmers, 

 without knowing the real cause of the crop rotation adopted by European 

 cultivators as the result of bitter experiences from ancient times on the ra- 

 vages of this dreadful disease, cultivated it at first without paying any atten- 

 tion to the necessity of rotation of crops. Consequently, the wilt disease 

 appeared in most severe form and even anniliilated often in many places the 

 whole crop of the flax field. 



In Japan the disease was first noticed at the end of the. nineteenth 

 centurj'. Prof Dr. K. Miyabe discovered in 1892, that a species of Fusarium 

 is concerned in the wilt disease of flax. The next year Dr. N. Hiratsuka 

 investigated this disease in our phytopatliological institute under the direc- 



