First report of Xanthomonas cucurbitae causing bacterial leaf spot of watermelon in the Seychelles.

Bacterial leaf spot of cucurbits caused by Xanthomonas cucurbitae (4) can be a harmful disease of several cucurbit species in tropical environments, mainly within the Cucumis, Cucurbita, and Citrullus genera. The bacterium induces angular, water-soaked leaf spots, which sometimes become necrotic and have a chlorotic halo. Scab-like lesions on fruit can also be observed (2). Water-soaked, angular leaf lesions were collected from approximately 15 watermelon plants (Citrullus lanatus) in a production field located in Mahe, Seychelles in 2003. Yellow-pigmented Xanthomonas-like bacterial colonies were isolated on KC semiselective medium (yeast extract 7 g, peptone 7 g, glucose 7 g, agar 18 g, distilled water 1,000 ml, propiconazole 20 μg ml–1, cephalexin 40 mg liter–1, and kasugamycin 20 mg liter–1) from all isolation attempts (3). Amplified fragment length polymorphism (AFLP) analysis was performed on four watermelon strains together with reference strains of Xanthomonas cucurbitae (LMG 690 [type strain] and ...