BROWN STEM OF CELERY CAUSED BY PSEUDOMONAS-CICHORII

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