154 Journal of Agrictdtural Research voi. xvi, No. s 



(4) The disease is caused by a species of Physoderma, one of the Phyco- 

 mycetes, which is probably identical with Shaw's Indian species, P. zeae- 

 maydis. 



(5) The sporangia of the fungus live over the winter on the old, dis- 

 eased corn plants and in the soil, and germinate the following summer by 

 producing numerous zoospores which infect the com plants and cause the 

 disease. 



(6) The sporangia require free water and a high temperature, 23 '^ to 

 30° C, for germination and host penetration, 



(7) The fungus is disseminated by wind and probably by other agen- 

 cies — for example, flowing water, insects, and various animals, including 

 man. 



(8) There is a possibility of controlling the disease to a certain extent 

 through sanitation, crop rotation, and resistant varieties, although this 

 has not been positively proved. 



LITERATURE CITED 

 i) Barre, H. W. 



[191 5.] REPORT OF THE BOTANIST AND PLANT PATHOLOGIST. Ill S. C. Agf. Exp. 



Sta. 27th Ann. Rpt. [i9i3]/i4, p. 20-25. 



2) 



1915. REPORT OP THE BOTANIST AND PLANT PATHOLOGIST. In S. C. Agr. 



Exp. Sta. 28th Ann. Rpt. [i9i4]/i5, p. 21-26. 



3) Clinton, G. P. 



1902. cladochytrium ALiSMATis. In Bot. Gaz., v. 33, no. i, p. 49-61, pi. 2-4. 



4) IvYMAN, G. R. 



1918. PLANT DISEASE SURVEY WORK ON THE PHYSODERMA DISEASE OF MAIZE. 



(Abstract.) In Jour. Wash. Acad. Sci., v. 8, no. 2, p. 43-44. 

 5) 



1918. THE RELATION OF PHYTOPATHOLOGISTS TO PLANT DISEASE SURVEY WORK. 



In Phytopathology, v. 8, no. 5, p. 219-228. 



6) Melchers, L. E. 



1918. PHYSODERMA (zEaE-maydis?) IN KANSAS. In Phytopathology, V. 8, no. 

 i'P-3&-39- 



7) MiNDEN, M. VON. 



1911. PiLZE. In Kryptogamenflora der Mark Brandenburg. Bd. 5, Heft 3. 



8) Sydow, H., Sydow, P., and Butler, E. J. 



1912. Fungi imdiaE orientalis. In Ann. Mycol., v. 10, no. 3, p. 243-280, 



II fig. Physoderma zeae-maydis Shaw nov. spec, p. 245—247, fig. 2. 



9) U. S. Department of Agriculture. Plant Disease Survey. 191 7. 



Bulletin 3, 62 p., 2 maps. 



