STUDIES OF DISEASE PRODUCING SPECIES OF FUSARIUM. 215 



typical species of Fusarium until a microscopic examination is 

 made of the spores. 



In May 1910 a diseased potato was sent to this laboratory by 

 Dr. G. E. Stone of the Massachusetts Agricultural College. 

 When material from the diseased surface of the tuber was 

 examined septate Fusarium spores were found. Cultures were 

 made from these and the fungus which developed, F IX, pro- 

 duced an abundance of spores of the obovate t^npe such as had 

 been found in F II from apples. Early in the study of this it 

 was noted that while the growth of mycelium was very similar 

 and the spores identical in shape and size to those of the fungus 

 from apple the proportion of obovate spores was much greater in 

 the potato fungus. With the latter, the septate spores were pro- 

 duced in the young colonies when obovate spores were sown in 

 agar plates but when aerial mycelium began to develop the 

 obovate spores were produced in greater numbers than the sep- 

 tate. 



In September 1910 a fungus, F VI, was isolated from diseased 

 ears of sweet corn. The same fungus has been found on sweet 

 corn a number of times since, but it is probable that the total 

 amount of loss caused by it is small. It agrees very closely in 

 its characteristics with F IX described above from potato. 



A fungus, F XIII, isolated from diseased heads of sunflower, 

 HeJianthus annuus L. shows the same characteristics as F II 

 from apple. While in older cultures it produces large numbers 

 of obovate spores there are always present a good proportion of 

 spores of the septate Fusarium type. This fungus causes a com- 

 plete decay of sunflower heads and destroys the seeds. Upon 

 inoculation the sunflower fungus was found to cause a rot of 

 carnation buds and 47 of the 71 buds inoculated were destroyed. 



In June and July. 191 1, a number of grasses on the University 

 grounds and farm at Orono showed silver-top. These grasses 

 were examined from time to time in order to determine whether 

 the fungus which Stewart found associated with the silver-top 

 of June grass in New York occurred in Maine and if it did occur 

 to isolate it from as many different grasses as possible for com- 

 parison with similar fungi from other sources. 



On June 7, 50 culms of June grass, Poa pratensis, affected 

 with silver-top were examined and only one was found which 

 showed the spores of a fungus. These spores agreed in size and 



