BACTERIAL FRUIT BLOTCH OF WATERMELON - ASSOCIATION OF THE PATHOGEN WITH SEED

Bacterial fruit blotch, a recently described disease of watermelon, resulted in severe losses to Indiana watermelon growers in 1989. Strains of the pathogen recovered from symptomatic fruit and seedlings exhibited similar phenotypic characteristics. Seedling symptoms (water-soaked lesions becoming necrotic on cotyledons and true leaves) and fruit symptoms (large, water-soaked blotches on the exposed rind surface) were induced by strains from both sources. Seed transmission was demonstrated in both seed from symptomatic fruit and seed soaked in a suspension of the bacterium. Treatment of naturally infested and laboratory-infested seed with 0.525% NaOCl for 20 min, 50-C H2O for 20 min, or 1.8% HCl for 5 min reduced disease incidence but did not eradicate the pathogen. The bacterium was recovered from seed coats and embryos of both naturally infested and laboratory-infested seed. The pathogen was not recovered from peduncles or stems of plants with symptomatic fruit. No transmission of the pathogen occurred in seed from inoculated, asymptomatic fruit. The pathogen was recovered in one seedling of nearly 9,000 grown from a commercial seed source.