Disease Note.

First Report of Bean Bacterial Wilt Caused by Curtobacterium flac-cumfaciens subsp, flaccumfaciens in North Dakota. J. R. Venette, Department of Plant Pathology, North Dakota State University, Fargo 58105-5012. R. S. Lamppa, and P. L. Gross, Department of Plant Pathology, North Dakota State University, Fargo 58105-5012. Plant Dis. 79:966. Accepted for publication 12 June 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0966B.

In November 1994, Curtobacterium flaccumfaciens: subsp, flaccumfa-ciens was recovered from a sample of navy bean (Phaseolus vulgaris L.) submitted by a local grower. A small portion (<2%) of the seed was discolored orange (WorksCoIor hue 27, sat. 220, lum 121, red 244, green 175, blue 13) or yellow (hue 30, sat 217, lum 129, red 243, green 190, blue 31). Aqueous extracts from individually soaked seeds contained numerous gram-positive bacteria. Axenic cultures were isolated on selective CNS medium (1), and five strains were characterized by Biolog (Biolog Inc., Hayward, Calif.) reactions. Strains suspended in sterile deionized water at a concentration of 1 x 108 were spray inoculated onto leaves and stab inoculated into stems of 10-day-old kidney bean cv. Charlevoix. Plants inoculated with water served as controls. Plants were maintained in the greenhouse at 25plus or minus 5°C with natural daylight extended to 14 h by high pressure sodium vapor lights. Within 7 to 10 days, inoculated areas of leaves developed characteristic white flecks, stab-inoculated plants wilted, and control plants remained healthy. While gram-positive bacteria were not isolated from control plants, numerous gram-positive colonies were isolated from inoculated plants. Representative strains derived from the reisolation produced identical Biolog characterizations. Reactions of original and reisolated strains were 60 to 90% similar to the Biolog profile for C. f subsp, flaccumfaciens. Reference cultures have been deposited with ATCC. Bacterial wilt has not been considered an important pathogen of beans for nearly 20 years and has not been previously described in the North Dakota-Minnesota bean production area. The disease threatens certified bean seed production where certification standards prohibit bacterial wilt. More than 230,000 ha of dry edible bean are grown in North Dakota, and 4,000 ha are in bean seed production.