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 (Gly cine man) fields in North Dakota, 80% had plants with obvious symptoms of bacterial blight. Strains (n = 164) isolated from field-grown plan ts and characterized as Pseudomonas syringae pv. glycinea were inocula ted onto wounded, fully expanded unifoliolate leaves of differential c ultivars Acme, Lindarin, Harosoy, Chippewa, Merit, Flambeau, and Norch ief. Reactions of the differentials showed that five of the eight know n races in the United States were present in North Dakota. Race 4 cons tituted 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 c haracterized as one of the known races.