Disease Note.

Tomato Pith Necrosis Caused by Erwinia chrysanthemi. Robert L. Wick, University of Massachusetts, Suburban Experiment Station, 240 Beaver Street, Waltham, MA 02154-8096. Robin Shrier, University of Massachusetts, Suburban Experiment Station, 240 Beaver Street, Waltham, MA 02154-8096. Plant Dis. 74:615. Accepted for publication 7 May 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0615F.

Wilted tomato (Lycopersicon esculentum Mill. 'Jet Star) plants with extensively hollowed stems and necrotic piths were found in a commercial field in Worcester County, Massachusetts. Bacteria recovered from the margin of diseased tissues were gram-negative, facultatively anaerobic, rod-shaped, motile, and pectolytic. Although not sensitive to erythromycin, the strains were positive for indole, phosphatase, lecithinase, gas production from glucose, gelatin liquefaction, growth at 39 C, utilization of malonate, and acid production from mannitol, melibiose, raffinose, and inulin. The strains failed to produce acid from trehalose and arabinose, to utilize tartrate, or to grow in KCN broth. These results are consistent with those expected for Erwinia chrysanthemi pv. chrysanthemi Burkholder, McFadden, and Dimock (1). Stab inoculations into the stems of three replications each of cultivars Jet Star and Caruso resulted in approximately 3 cm of pith degradation after 3 wk. Vascular discoloration occurred for several centimeters beyond the necrosis in two of the six plants. Koch's postulates were completed by reisolation and identification of the bacterium. E. chyrsanthemi pv. zeae has been reported to cause soft rot and pith necrosis of tomato in the Cauca Valley, Colombia. This is the first report of E. chrysanthemi as a cause of tomato pith necrosis in the United States.