138 



Journal of Agricultural Research 



Vol. XVI, No. s 



specimens of the disease at Manhattan, Kansas, but, not being sure of its 

 identity, kept the specimens until 191 7 before making his report. A 

 number of farmers throughout the South have told the writer that the 

 disease has been present on their farms for many years. It was no doubt 

 present in this country a long time before being reported by pathologists. 



DISTRIBUTION AND PREVALENCE 



Tn the third issue of the Plant Disease Survey Bulletin (9, p. 52), Sep- 

 tember 15, 1 91 7, the writer published a map showing the known distribu- 

 tion of Physodermazeae-madyis and the localities in which there was notice- 

 able damage. The disease at that time seemed to be rather thoroughly 



Fig. 



-Map showing the distribution of Physodertna zeae-^maydis in the United States. Broken lines, 

 P. zcae-maydis present: solid line, P. zeae-maydis causing damage. 



distributed throughout the Southern States as far north as North Carolina 

 and Tennessee and west to the Mississippi River. Only single instances 

 of its occurrence were known in Illinois and Ohio. Melchers ((5) since that 

 time has reported its occurrence in Kansas as early as 191 5. In Sep- 

 tember and October, 191 7, in cooperation with the Office of Plant Disease 

 Surv^ey, a detailed study was made of the prevalence and importance of 

 the disease in representative localities of the infested area of the South- 

 east, not including Florida. The survey was also extended to deter- 

 mine the distribution of the disease throughout the United States. The 

 disease was found to be prevalent practically throughout all localities 

 where the detailed survey was made, very few fields being entirely free 

 from it. The writer found diseased corn plants on the Blue Ridge 

 Mountains of North Carolina at an elevation of about 3,000 feet. How- 

 ever, it was much less abundant than on the lowlands of the State. In 

 the more extensive surv^ey the disease was found to occur in Arkansas, 



