PATHOGENICITY AND CHARACTERIZATION OF ERWINIA-ANANAS CAUSING A POSTHARVEST DISEASE OF CANTALOUP FRUIT

Cantaloups (Cucumis melo var. reticulatus) grown in the Rio Grande Valley of Texas developed small, water-soaked lesions after harvest. Lesions were shallow, firm, and, in many cases, not easily detected until the peel was removed. A yellow bacterium was isolated on nutrient agar and used to fulfill Koch's postulates. The bacterium was nonfluorescent, gram-negative, rod-shaped (0.5-1.1 x 0.9-3.5-mu-m), motile, and capable of anaerobic growth. Mucoid colonies were produced on high sugar media. The bacteria grew at 36 C and on Miller-Schroth medium. The pathological and physiological attributes of the bacterium fit the description of Erwinia ananas. Strains from cantaloup reacted positively in ELISA tests with antibodies against reference cultures of E. ananas, and cellular fatty acid profiles were identical to those of the E. ananas-E. herbicola group. This disease of cantaloup extends the known host range of E. ananas and may become an economically important postharvest decay of melons grown in the Rio Grande Valley of Texas.