Occurrence of bacterial spot disease, caused by Xanthomonas axonopodis pv. vesicatoria, on pepper in the eastern Mediterranean region of Turkey

During the summers of 1999 to 2002, a survey of commercial pepper fields was conducted in the eastern Mediterranean (Adana and Osmaniye) region of Turkey. All the pepper fields planted with a local cultivar (cv. Salcalik) were found to be infected with a bacterial spot disease (Fig. 1).

Disease incidence was estimated to be in the range 50-95%. A yellow-pigmented bacterium was consistently isolated onto Tween medium (Mcguire et al., 1986) from diseased pepper plants grown in 82 different fields. Thirty representative strains selected were gram-negative, rod shaped, motile, aerobic, oxidase negative, catalase positive and amylolytic positive. All of the strains were identified as Xanthomonas axonopodis pv. vesicatoria (Doidge) Dye (Xav) (similarity 66 to 94 %) using fatty acid methyl ester (FAME) analysis and Sherlock Microbial Identification System software (Microbial ID, Newark, DE, USA) (Bouzar et al., 1994, Jones et al., 1998). They all produced positive hypersensitive reactions on tobacco (Nicotiana tabacum cv. Samsun), and were pathogenic on pepper (cv. Salcalik) and tomato (cv. H-2274) plants. Xav strains were also recovered from seed lots of cv. Salcalik. This result suggested that the primary inoculum source of the disease was contaminated seed used in this region. Occurrence of Xav on pepper grown in the eastern Anatolia region of Turkey has been reported previously (Sahin, 2001), but this is the first report of the observation of Xav in the eastern Mediterranean region of Turkey.