Occurrence in Johnsongrass of Rickettsia-like Bacteria Related to the Phony Peach Disease Organism. D. J. Weaver, Research Plant Pathologist, Southeastern Fruit and Tree Nut Laboratory, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Byron, GA 31008. B. C. Raju, Research Plant Pathologist, Department of Plant Pathology, University of California, Davis 95616; J. M. Wells, Research Plant Pathologist, Southeastern Fruit and Tree Nut Laboratory, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Byron, GA 31008; S. K. Lowe, Research Associate, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 64:485-487. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/PD-64-485.

Rickettsia-like bacteria (RLB) were consistently observed in KOH extracts of johnsongrass stems collected in peach orchards with phony disease. Electron microscopic examination of xylem in leaves of johnsongrass revealed RLB morphologically similar to those associated with phony peach and other xylem-limited, leafhopper-vectored diseases. Johnsongrass RLB were antigenically related to RLB associated with phony peach and Pierce’s disease. RLB in johnsongrass are closely related to the phony disease organism, and johnsongrass is a possible natural reservoir of RLB associated with phony peach disease.

Keyword(s): Prunus persica, Sorghum halepense, xylem-limited bacteria.