LETTER OF TRANSMITTAL 



U. S. Department of Agriculture, 



Bureau of Plant Industry, 



Office of the Chief, 

 Washington, D. C, March 25, 1911. 

 Sir: I have the honor to transmit herewith a technical paper enti- 

 tled "The Rusts of Grains in the United States," by E. M. Freeman, 

 Collaborator, and Edward C. Johnson, Pathologist in Charge of 

 Cereal Disease Work. This paper embodies the results of recent 

 research by the Office of Grain Investigations in cooperation with the 

 Minnesota Agricultural Experiment Station into the distribution, 

 relationships, physiology, and life history of the important grain 

 rusts, and gives much new information on the "biologic forms" of 

 rusts, vitality of successive uredo generations, wintering of the 

 uredo generation, and climatology in relation to rust epidemics. 

 Former experiments on rust prevention are summarized and methods 

 of selection and breeding of grains for rust resistance indicated. 



The grain rusts continue to be of large economic importance, and 

 as this paper is another step advancing our knowledge concerning 

 them I recommend that it be published as Bulletin No. 216 of the 

 series of this Bureau. 



Respectfully, Wm. A. Taylor, 



Acting Chief of Bureau. 

 Hon. James Wilson, 



Secretary of Agriculture, 



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