Brown Stem of Celery Caused by Pseudomonas cichorii . KEN PERNEZNY, University of Florida, IFAS, Everglades Research and Education Center, Belle Glade 33430-8003. LAWRENCE DATNOFF, University of Florida, IFAS, Everglades Research and Education Center, Belle Glade 33430-8003, and MARK L. SOMMERFELD, A. Duda & Sons, Inc., Belle Glade, FL 33430-0208. Plant Dis. 78:917-919. Accepted for publication 27 May 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0917.

An unusually severe outbreak of a petiole necrosis of celery, known as brown stem, was observed in the winter of 1993 in southern Florida. Pseudomonas cichorii was consistently recovered from naturally infected tissue. Bacterial strains were gram-negative rods, fluorescent, oxidase-positive, and arginine dihydrolase-negative. Negative reactions were recorded for levan production, potato soft rot, and fermentation of glucose. Strains utilized mannitol, D-aspartate, and m-tartrate for growth. No growth was recorded for D-arabinose, cellobiose, sucrose, trehalose, benzoate, DL-lactate, D-tartrate, erythritol, or sorbitol. A hypersensitive response was recorded in leaf tissue of pepper cv. Early Calwonder. Brown stem and typical leaf spot symptoms were readily reproduced with test strains in greenhouse-grown celery.