Detection of Xanthomonas campestris pv. vignicola in Southern Pea Seed. R. D. Gitaitis, Department of Plant Pathology, University of Georgia, Coastal Plain Station, Tifton 31793. S. S. Nilakhe, Department of Entomology and Fisheries, University of Georgia, Coastal Plain Station, Tifton 31793. Plant Dis. 66:20-22. Accepted for publication 27 April 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-20.

A method was devised for detecting Xanthomonas campestris pv. vignicola in southern pea (Vigna unguiculata) seeds. Samples of 100 seeds were infused with 100 ml of sterile water by the sudden release of 680 mm of mercury vacuum. Seeds were agitated at 150 rpm for 2 hr on an orbital shaker, and the suspensions were centrifuged at 4,000 g for 30 min. Pellets were resuspended in 5 ml of supernatant and the mixture was infiltrated with a syringe and needle into healthy leaves of southern pea. Bacteria recovered from lesions that developed in 5–20 days were identified as X. campestris pv. vignicola. Incidence of bacterial blight in field plots was significantly greater in cultivars that were grown from heavily infested seeds. Bacteria were isolated from seed produced in Florida, Georgia, and Texas, as well as in California.

Keyword(s): cowpea.