VIEW ARTICLE

Electron Microscopy in situ of the Bacterium Associated with Ratoon Stunting Disease in Sundangrass. J. F. Worley, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705; A. G. Gillaspie, Jr., Beltsville Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705. Phytopathology 65:287-295. Accepted for publication 30 September 1974. DOI: 10.1094/Phyto-65-287.

Basal stem tissue of sorghum-sudangrass hybrid uprights (two-node cuttings with the lower bud removed) with symptoms of ratoon stunting disease were sectioned for electron microscopy. These thin-sections revealed the presence of many rod-shaped bodies in the large xylem vessels. The bodies measure about 0.3 - 0.4 by 5-10 µm, and have a smooth cell wall indicative of a bacterium. The frequency of septa, and lack of evidence for binary fission, suggest that the organism belongs to the coryneform group of bacteria. A similar organism was seen, but far less often, in ratoon stunt-infected sugarcane.