ties and the remainder on ten, 

 mi was obtained. At least f< tin- 

 distinct races were differentiated on the basis of the behavior of 

 the collections on such varieties as Hussar. Martin. Odessa, Kanred 

 and Turkey. It is possible that the actual number of races is 

 greater, but the varieties grown during tbe ]>ast year were not 

 sufficient for a clear differentiation. 



Similarly, twenty-one collections of T. tritici were used, nine 

 being sown on eighteen varieties and tbe remainder on ten. Again 

 clear-cut evidences of the occurrence of specialized races were ob- 

 tained and the results of previous years confirmed. Again the 

 varieties Hussar, Martin, Odessa. Kanred and Turkey served as 

 differential hosts, and at least six races were clearly defined. 



It is evident from these results that both species of the bunt of 

 wheat, like the two smuts of oats, tbe covered smut of barley, and 

 other smuts, are differentiated into well defined physiologic nice-. 

 The existence of such races greatly complicates the problem of 

 successfully breeding resistant varieties, and their occurrence must 

 lie recognized before real progress can be made. 



It is also necessary to keep clearly in mind the importance of 

 environal conditions on the infection of wheat by bunt. Soil 

 temperature, soil moisture, soil reaction, etc.. are extremely im- 

 portant in influencing the extent of the infection. 



The most important results on these problems have been pre- 

 pared for publication and will be issued from the press earlv in 

 1928. 



I'hysiolor/ic Races of Covered Smut of Barley 

 In previous reports the interesting results on the covered smut 

 of barley (Ustiluyo hordei) obtained by Dr. James A. Faris, 

 Resident Investigator in Plant Pathology in tbe Brooklyn Botanic 

 Garden (1921-4), have been mentioned. Dr. Paris clearly proved 

 the existence of specialized races of this fungus, which were 

 identified by their capacity for infecting certain varieties of barley. 

 Additional studies have been made with the races originally dif- 

 ferentiated, together with new collections of smut from other 



Xo attempt has been made as yet to determine tbe behavior of a 



