First report of bacterial blight of anthurium caused by Xanthomonas axonopodis pv. dieffenbachiae in Turkey

In the spring of 2001, a serious outbreak of a suspected bacterial blight disease was observed on anthurium plants (Anthurium andreanum) grown for potted plant production in commercial greenhouses of the Mediterranean region in Turkey. Disease incidence was recorded in the range 20-25%. Bacterial blight symptoms evident on lower surface leaves were small, yellowish water-soaked spots that enlarged and coalesced. Eventually, brown to black blighted areas were often observed together with a striking yellow zone along leaf margins (Fig. 1). A gummy bacterial exudate sometimes flowed down from the infected plant parts. Stems appeared black, wet and slimy from the bacterial growth in the pith area (Fig. 2). A yellow-pigmented bacterium was consistently isolated from diseased plants onto ET Agar (Norman & Alvarez, 1989).

Eighteen representative strains isolated were gram-negative, rod shaped, motile, aerobic, oxidase negative, catalase positive and amylolytic positive. They all produced postive hypersensitive reactions on tobacco (Nicotiana tabacum cv. Samsun). All of the strains were identified as Xanthomonas axonopodis pv. dieffenbachiae (McCulloch & Pirone) Dye (Xad) based on fatty acid methyl ester (FAME) profiles determined by Sherlock Microbial Identification System software (Microbial ID, Newark, DE, USA) (Bouzar et al., 1994, Jones et al., 1998), and pathogenicity studies on anthurium plants. Since the occurrence of bacterial blight disease on anthurium grown in Turkey has not been reported previously, this is the first report of the observation of Xad in Turkey.