Isolation of Acidovorax citrulli fromseeds, seedlings, fruits of watermelon and efficacy of different seed treatments on seedling blight disease occurence

Bacterial pathogen Acidovorax citrulli, causes seedling blight and fruit blotch on cucurbit crops. From surveys conducted in watermelon fields and commercial nurseries located in Adana, Osmaniye and Antalya provinces, 84 phytopathogenic bacteria were isolated from symptomatic plant materials. Identification of isolates were revealed using gram reaction, colony morphology on several media, LOPAT (L: levan production, O: oxidasetests, P: pectolyticactivity on potatoslices, A: argininedehydrolasetests, T: hypersensitivity on tobacco) tests, pathogenicity, DASELISA and PCR. Between 2009-2012, 217 watermelon and rootstock seed lots belonging to 48 distinctive varieties imported from 16 different countries were tested and Acidovorax citrulli was not detected in those seed lots. In order to reduce or eliminate the bacterial inoculum on seed, effects of twenty-one different physical and chemical seed treatments to disease incidence, seed germination and seedling growth was investigated. Neither of treatments were inhibited the pathogen inoculum on seeds. According to results, the most successful four seed treatments were dipping in to 2% lactic acid for 15 and 20 minutes, 55 oC for 20 minutes and. 60 oC for 20 minutes. KeyWords: Watermelon, Acidovorax, PCR, ELISA, physical and chemical seed treatments