JOMAL OF AGBICOITDRAI RESEARCH 



Vol. XVIII Washington, D. C, Nov. 15, 1919 No. 4 



BACTERIAL BLIGHT OF SOYBEAN 



By Florence M. CoerpER 

 Insimctor in Plant Pathology, University of Wisconsin ' 



INTRODUCTION 



For a number of years a bacterial blight of soybean has been under 

 investigation at the University of Wisconsin. The early observations 

 were made during several seasons prior to 191 5 in the university experi- 

 mental plots by Dr. L- R. Jones and Dr. A. G. Johnson, of the depart- 

 ment of plant pathology. In September of that year more intensive 

 study of the trouble was undertaken by the writer. At this time the 

 disease was very severe in Madison fields. Scarcely a plant could be 

 found free from the spotting, and the leaf area of approximately 20 per 

 cent of the crop was destroyed to such an extent as to affect materially 

 the growth of the plants. Subsequent observation has proved the blight 

 to be very prevalent throughout the soybean fields of Wisconsin, and a 

 disease showing symptoms of the same type has been reported from 

 various other localities in the United States. 



LITERATURE 



Literature, up to this time, gives no detailed description of the disease 

 or of its causal organism, although the malady has, no doubt, been 

 observed in the field for many years. Smith ^ mentions a bacterial leaf- 

 spot of soybean but does not record a thorough study of it. The only 

 other references, with the exception of an abstract^ published in 191 7, 

 seem to be a note by Heald * and a later report with figure by Clinton,^ 

 both of which give short descriptions of the symptoms. There seems no 

 reason to doubt that these workers had under observation the disease 

 described in this paper. 



In addition it should be recorded that Manns" in 191 5 described a 

 bacterial organism pathogenic upon certain legumes, including soybeans. 



' The writer wishes to make grateful acknowledgements to Dr. L. R. Jones and Dr. A. G. Johnson, of the 

 University of Wisconsin, for supervision and helpful suggestions during the progress of this work. 



^ Smith, Erwin F. bacteria in relation to plant diseases, v. i, p. 92, 1905; v. 2, p. 69, 1911. Wash- 

 ington, D. C. (Camejie Inst. Washington, Pub. 27.) 



' Johnson, A. G., and CoERPER, Florence M. b.^cterlu, blight of so\'be.\n. (Abstract.) /n Phyto- 

 pathology, V. 7, no. I, p. 65. 191 7. 



* Heald, Frederick DeForest. report on the pl^vnt diseases prevalent in Nebraska during the 

 SE.\soN of :90s. In Ncbr. Agr. Exp. Sta. 19th Ann. Rpt., 1905, p. 71. 1906. 



' Clinton, G. P. notes on plant diseases of Connecticut. In Conn. Agr. Exp. Sta. Ann. Rpt., 1915, 

 p. 444-446. 1916. 



'Manns, Thomas F. some new bacterial diseases of legumes and the relationship of the 

 organisms causing the same. Del. Agr. Exp. Sta. Bui. 108, 44 p., 21 pi. 1915. 



Journal of Agricultural Research, Vol. XVIII, No. 4 



Washington, D. C. Nov. 15, 1919 



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