20 



Mycologia 



observed at Lincoln, Nebraska, which has been found to be due 

 to a hitherto undescribed fungus. The disease has proved very 

 destructive, hence its consideration is of economic importance. 



The disease is characterized by the sudden dying of the plants. 

 Individuals which are apparently healthy will in a few days be 

 dry and dead. When one of these is puUed up, a dark, slightly 

 sunken area on the stem just at the surface of the ground is 

 apparent. The root-system is destroyed so that only stubs of the 

 main roots are left, the smaller parts having been disintegrated. 

 Several entire beds were observed to be thus destroyed, the dying 

 occurring in the month of July. 



On July 12, 1907, plants from a bed which was then almost 

 completely lost, were brought into the laboratory. The stems 

 were first washed in tap-water and then dipped for a moment in 

 a mercuric chloride solution i : 1000. The outer parts were then 

 removed with a sterile scalpel and a portion of the inner tissue 

 from one of the diseased areas was placed on glucose agar plates. 

 When proper precautions were observed to prevent contamination, 

 these plates gave in every instance pure cultures of a Fusarium. 



The species of Fusarium /iave been generally regarded as sap- 

 rophytic. Within the last few years, quite a number have been 

 found to be truly parasitic during part of their life, or at least 

 facultative saprophytes. Among these are a flax wilt* reported 

 from North Dakota; a species which destroys green tomatoesf 

 in the field ; and another which attacks cultivated peas.J 



In order to determine the mode of life of this species of 

 Fusarium, inoculations were made during the summer of 1908. 

 A small portion of the agar with the hyphae and spores was 

 placed just beneath the surface of the ground near the plants, 

 care being taken to inflict no injury to them. In a month these 

 plants had developed the characteristic brown areas on the stems 

 and died, while the check plants remained normal. Planted plates 

 made from the diseased places, using the same care as before to 

 prevent contamination, gave in turn pure cultures of the Fusarium. 

 Microscopic examination revealed the presence of fungus fila- 



*Bolley, Bull. N. D. Exp. Sta. 50. 1901. 



t Smith, Tech. Bull, Mass. Exp. Sta. 3. 1907. 



+ Schikora, Dissertation Berlin, 1-34. 1906. 



