MOSAIC DISEASE OF CORN ' 



By E. W. Brandes 



Pathologist, Office of Sugar-Plant Investigations, Bureau of Plant Industry, 

 United States Department of Agriculture 



DISTRIBUTION 



In connection with an investigation of the mosaic disease of sugar 

 cane, a similar disease of corn has been observed by the writer on several 

 occasions in widely separated regions.^ On April i8, 191 9, corn of an 

 unknown variety was seen to be affected with typical mosaic symptoms 

 in a field just west of Penuelas, P. R. The percentage of affected plants 

 was small, however, only 20 individuals being found in the field of some 

 5 acres. The corn averaged about 24 inches in height at this time and 

 was planted between rows of sugar-cane stubble which had not been 

 completely killed out in preparing the land for the com. All the sugar 

 cane was affected with mosaic. In July, 191 9, corn of the White Creole 

 variety was seen at the Sugar Experiment Station, New Orleans, La., 

 in which the same condition was apparent. This com was more than 

 half grown, and the typical streaking of the leaves was somewhat ob- 

 scured by certain leafspot diseases, among them the leafspot caused by 

 Physoderma zeae-maydis , by which the com was severely attacked. About 

 10 per cent of the plants in the field were affected with mosaic. In adjoin- 

 ing fields of sugar cane nearly 100 pe'r cent of the plants were affected with 

 the sugar-cane mosaic. In 1920 corn of the same variety was examined 

 early in the season, and a much more serious infestation was found. 

 The com had been planted following sugar cane, and occasional diseased 

 stools of the latter not killed by the plow were found all through the 

 com field. More than 30 per cent of the corn plants were affected. The 

 cases were more abundant in the vicinity of the sugar-cane stools re- 

 ferred to above, but cases could be found many rods from any living cane. 

 Of course, it is possible that a stool of cane had sprouted between the 

 rows in such a situation and later had been killed by the cultivator. In 

 May, 1920, identical cases of mosaic were seen in a field of corn near 

 Cairo, Ga. As in the cases reported previously, a neighboring field of 

 sugar cane was slightly infested with mosaic. 



• The study of this disease was undertaken on account cf its relation to sugar-cane mosaic. 

 2 Brandes, E. W. the mosaic disease of sugar cane and other grasses. U. S. Dept. A^. Bui. 

 829, 26 p., 5 fig., I col. pi. 1919. 



Journal of Agricultural Research, Vol. XIX, No. lo 



Washington, D. C. Aug. i6, 1920 



va Key No. 0-203 



(517) 



