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Disease Note.

First Report of Bacterial Fruit Blotch of Watermelon in Texas. M. C. Black, (Uvalde 78802), Department of Plant Pathology and Microbiology, Texas A&M University. T. Isakeit (Weslaco 78596), and L. W. Barnes (College Station 77843), Department of Plant Pathology and Microbiology, Texas A&M University; and T. A. Kucharek, R. J. Hoover, and N. C. Hodge, Plant Pathology Department, University of Florida, Gainesville 32611. Plant Dis. 78:831. Accepted for publication 12 April 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0831C.

Bacterial fruit blotch of 'Royal Sweet' and 'Allsweet' watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) was diagnosed from ma-lure fruits collected in Frio and Duval Counties, respectively, in June 1993. Lesions were water-soaked, dark green, and had irregular margins that did not extend into the flesh of the fruit. In older lesions, the epidermis was brown and cracked. Necrotic leaf lesions were evident in plants from Frio County. Bacterial streaming was observed from margins of fruit lesions. Bacteria isolated from fruit lesions at both locations were identified as Acidovorax avenae subsp, citrulli Willems (2) (syn. Pseudomonas pseudoalcaligenes subsp, citrulli Schaad et al) by the Texas Plant Disease Diagnostic Laboratory, College Station, using the Microbial Identification System (MIS) fatty acid profiles (similarity index of 0.50). Representative isolates from both locations were sent to the University of Florida (UF), where hypersensitive responses were produced on tobacco (Nicotiana tabacum L). Fatly acid analyses conducted at UF showed similarity indices of > 0.820 to the bacterial fruit blotch pathogen described by Somodi et al (1). The affected fields received above-average precipitation in May and early June 1993. Fewer than 100 acres were known to be affected. Incidence of diseased fruit in Frio County was approximately 50% in affected parts of fields.

References: (1) G.C. Somodi et al. Plant Dis. 75:1053, 1991. (2) A. Willems et al. J. Syst. Bacteriol. 42:107, 1992.