JOINAL OFAGiaaiTDRAlRESEARCH 



Vol. XVI Washington, D. C, February 3, 1919 No. 5 



PHYSODERMA DISEASE OF CORN 



By W. H. TiSDALE 



Assistant Pathologist, Cereal Investigations, Bureau of Plant Industry, United States 



Department of Agriculture 



INTRODUCTION 



In recent years the Physoderma disease of corn (Zea mays) has been 

 reported as doing considerable damage in the southern part of the United 

 States. The uncertainty as to the distribution of the disease and its 

 economic importance, together with the lack of a knowledge of the life 

 cycle and parasitism of the causal organism and the possibility of its 

 becoming a serious pest in the Com Belt, led the Office of Cereal Investi- 

 gations to undertake an exhaustive investigational study of the problem. 

 This work was undertaken by the writer in December, 191 6. Since that 

 time certain phases of the problem have been more or less completely 

 developed, while others are in need of further study. 



HISTORY OF THE DISEASE 



Shaw (Sy in 1 91 2 reported the occurrence of the disease in India as early 

 as 1910, and gave a short description of the causal organism. At the 

 annual meeting of the American Phytopathological Society at Cleve- 

 land, Ohio, 1 91 2, Barrett^ reported the occurrence of the disease in Illi- 

 nois in 191 1. In a personal interview Barrett stated that he received 

 specimens of diseased com from Ohio and North Carolina. Barre (j, 

 p. 23) states that the disease was known to be present in South Carolina 

 as early as 191 1,. and since that time has been doing considerable damage. 

 Reports of the occurrence of the disease in Georgia in 1910 have come to 

 the writer indirectly, but he has never been able to confirm them. There 

 is no reason, however, to doubt its cocurrence in Georgia at that time, 

 since it is now known to be so widespread throughout the country. 

 Prof. J. M. Beal, of the Mississippi Agricultural College, noted the disease 

 in Mississippi as early as 1914. Mr. A. P. Spencer, of the Florida Agricul- 

 tural College, claimed that considerable damage was caused by it in Lake 

 County, Florida, in 191 5. In the summer of 191 5 Melchers (d) collected 



' Reference is made by number (italic) to "Literature cited," p. 154. 



2 Barrett, J. T. physoderma zeae-maydis shaw in Illinois. Not published. Reference to title 

 only in Phytopatholoay, v. 3, no. i, p. 74. 1913. 



Journal of Agricultural Research, Vol. XVI, No. 5 



Washington, D. C. Feb. 3, 1919 



rg Key No. G-163 



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