LETTER OF TRANSMITTAL 



U. S. Department of Agriculture, 



Bureau of Plant Industry, 



Office of the Chief, 

 Washington, D. C, February 25, 1910. 



Sir : I have the honor to transmit herewith and to recommend for 

 publication as Bulletin No. 181 of the Bureau series a manuscript 

 entitled "The Curly-Top of Beets," by Harry B. Shaw, Assistant 

 Pathologist in Cotton and Truck Diseases and Sugar-Plant Investi- 

 gations of this Bureau, in cooperation with the Bureau of Ento- 

 mology. 



The sporadic outbreaks of this disease have caused much loss to 

 sugar-beet growers in our Western States during the past ten years. 

 Curly-top has been under investigation by this Bureau since 1902, and 

 Bulletin No. 122 of this Bureau, by Dr. C. O. Townsend, was pub- 

 lished in 1908 to show the lack of proof that bacteria, fungi, or un- 

 favorable environmental conditions were the cause of curly-top. 

 Since that date Mr. Shaw has proved that the disease results from the 

 punctures of an insect, a theory previously advanced by Dr. E. D. 

 Ball, then special agent of the Bureau of Entomology. This group 

 of plant diseases, another example of which is stigmonose of carna- 

 tions, described by Mr. A. F. Woods in Bulletin No. 19 of the 

 Division of Vegetable Physiology and Pathology, is of special inter- 

 est to the plant pathologist on account of the physiological problems 

 involved, but the practical control of these troubles must be based 

 largely upon studies by the entomologist. 



To make this discussion of curly-top more complete and of greater 

 practical value Mr. Shaw has included a description of the beet leaf- 

 hopper and its life history, largely drawn from the work of Dr. E. D. 

 Ball, whose assistance, and that of Dr. F. H. Chittenden, of the 

 Bureau of Entomology, is gratefully acknowledged. 



Further knowledge of the most effective means of control is hoped 

 to result from studies planned in cooperation with the Bureau of 

 Entomology. 



Respectfully, G. H. Powell, 



Acting Chief of Bureau. 



Hon. James Wilson, 



Secretary of Agriculture. 



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