Acidovorax citrulli is the causal agent of bacterial fruit blotch disease of watermelon and melon. The disease was first reported in 2005 in Cukurova Region, Turkey. In summer of 2009-2011, severe disease symptoms and significant economic losses were observed on watermelon (Citrullus lanatus cv. Blade, Zeugma, Crisby and Starburst) and melon (Cucumis melo cv. Surmeli) in some villages of Adana and Osmaniye in the region. Pathogen is seedborne and first inoculum sources are infected seeds or seedlings. Initial symptoms in nurseries observed water soaked small lesions on cotyledons. Reddish brown to dark brown, irregular and rarely greasy symptoms can be observed on watermelon true leaves. Pathogen can get through true leaves to fruit. Mostly, dark oil green lesions are observed on pericarp of fruit. Those lesions surround the entire fruit surface within 5-8 days; brown cracks, amber colored and foaming like stream appears on diseased fruit. Symptoms on melon are light brown, water soaked and irregular spots on true leaves, brown, receding lesions and cracks on surface and finally soften and rotten of melon observed. The disease caused significant economical losses and nearly 5000 da watermelon fields were quarantined by the authorities and banned to grow watermelon or other cucurbits for 4 years in the region. Many watermelon and melon seedlings were destroyed in the nurseries because of the disease. In the PhD study, of 85 bacterial strains, 70 strains from watermelon and 15 strains from melon were isolated from diseased watermelon and melon plants. The strains were identified as Acidovorax citrulli according to the morphological, physiological, biochemical, pathogenicity and PCR tests. Based on the studies, occurrence and outbreak of bacterial fruit blotch of melon and watermelon, causal agent of Acidovorax citrulli were determined in Cukurova Region.