Edward J. Sikora, Extension Plant Pathologist Plant Disease Notes Bacterial Fruit Blotch Fruit blotch, caused by a bacterium which has yet to be classified, infects watermelon. Since 1989, the disease has occurred in one or more states on the eastern seaboard, including Alabama. The fruit blotch bacterium can cause seedling blight, leaf spot, and a fruit disorder. Lesions develop and are often accompanied by a yellow halo.
Foliar symptoms can occur throughout the growing season but are difficult to detect.
Leaf lesions, which act as a reservoir of bacteria for subsequent fruit infection, are tan to reddish brown and usually appear along the midrib. Defoliation is not common. Spots enlarge rapidly to irregularly shaped, dark green, water-soaked lesions of several centimeters. In a few days these lesions may expand to cover the entire upper surface of the fruit. Fruit lesions do not extend into the flesh of the melon initially.