Races of Pseudomonas syringae pv. glycinea on Commercial Soybean in Eastern North Dakota

In a survey conducted from 1991 to 1993 of 170 commercial soybean (Glycine max) fields in North Dakota, 80% had plants with obvious symptoms of bacterial blight. Strains (n = 164) isolated from field-grown plants and characterized as Pseudomonas syringae pv. glycinea were inoculated onto wounded, fully expanded unifoliolate leaves of differential cultivars Acme, Lindarin, Harosoy, Chippewa, Merit, Flambeau, and Norchief. Reactions of the differentials showed that five of the eight known races in the United States were present in North Dakota. Race 4 constituted 63%, race 6 was 22%, race 2 was 7%, race 3 was 0.3%, and race 5 was 0.1% of the race profile. Five pathogenic strains could not be characterized as one of the known races.