Disease Note

Leaf Spot Diseases of Dracaena sanderana Caused by Two Species of Erwinia. A. R. Chase, Plant Pathology Department, University of Florida Agricultural Research Center, Apopka 32703, and D. D. Brunk, Plant Disease Diagnostics, Inc., Apopka. Plant Dis. 68:251, 1984. Accepted for publication 15 December 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-251e.

A leaf spot of Dracaena sanderana Hort. Sander. M. T. Mast. was observed in several nurseries in central Florida.  The tan-to-black water-soaked lesions were 1–2 cm wide and formed on leaf margins and petioles.  Erwinia herbicola and E. carotovora pv. carotovora were isolated from different plants.  Leaves of healthy dracaenas were injected with 1 × 10⁸ or 10⁴ cfu/ml of a bacterial suspension ( E. herbicola or E. carotovora pv. carotovora) or sterilized water.  After 2 wk, 1-cm wide greasy black lesions formed at sites inoculated with either Erwinia sp. but not at sites inoculated with water.  Lesions caused by E. carotovora pv. carotovora were larger than those caused by E. herbicola, but all lesions had water-soaked margins and expanded past the initial water-soaked injection area.  Both pathogens were reisolated from the advancing margins of respective lesions.  The test was repeated twice, with similar results.