38 



Appended Papers 



The Reports on Research for 1924, the administrative reports 

 of members of staff, the financial statement, and Appendices 

 1-7 will be found on the following pages. 



Respectfully submitted, 



C. Stuart Gager, 



Director. 



REPORTS ON RESEARCH EOR 1924 



Plant Pathology 



Investigations with Oat Smuts. By George M. Reed 



Specialized Races of Oat Smuts. — The most significant dis- 

 covery in connection with the investigations of the oat smuts has 

 been the existence of specialized races of both the loose smut 

 {Ustilago avenae) and the covered smut {Ustilago levis). Some 

 evidence of the existence of such races was obtained in 1923 but 

 the question was finally settled in tlie experiments during the 

 past year. Two strains of loose smut, one from Missouri and 

 the other from Wales, have been compared. In the main they 

 are similar in their capacity for infecting oat varieties but they 

 show evident differences. Both seem capable of attacking a 

 wide range of varieties of oats. It is also interesting that certain 

 strains of varieties, like Black Mesdag, have proved to be ex- 

 tremely resistant to both races. The two strains of covered 

 smut, one from Missouri and one from Wales, are quite distinct. 

 The Missouri strain is capable of attacking a large number of 

 varieties of oats, belonging to the various species or sub-species of 

 Avena. The Welsh strain, however, seems to be confined almost 

 entirely to certain varieties of Avena strigosa and also to a strain of 

 Avena hrevis. For the most part the same varieties of A. strigosa 

 are also susceptible to the Missouri strain. Avena hrevis, how- 

 ever, has proved to be c}uite resistant to the latter, although 

 occasional infections have been obtained. A large amount of 

 additional data has been secured bearing upon this problem of 

 physiological specialization. It is, however, a problem which 

 involves the growing of a large number of oat varieties, as well 



