Loss figures were obtained for diseases caused by 43 bacterial species, seven mycoplasmalike organisms, and three rickettsialike organisms in 31 states in 1975, 1976, and 1977. The most frequently mentioned pathogens were Erwinia amvlovora and E. carotovora. Of 17 diseases cited as most important in a state, eight also were cited as second or third in importance in other states. Pathogens of greatest significance were,' in decreasing order: Xanthomonas vesicatoria, E. carotovora, Agrobacterium tumefaciens, Corvnebacterium sepedonicum, X. malvacearum, E. amy'lovora, Pseudomonas glvcinea, and P. syringae. The pathogen causing the greatest dollar-loss per year ($54.5 X 106) was P. glycinea in Iowa. Dollar-losses from P. albo-precipitans and P. andropogonis are not among the top 14 in this survey but were in the top 10 in a similar survey published in 1971.
Parents and F3 families of seven soybean crosses were studied for reaction to the bacterial blight organism, Pseudomonas glycinea Coerper. Six of the crosses were tested in both the field and the greenhouse to a single colony isolate of the organism obtained at St. Paul, Minnesota, and four were tested under similar conditions to an isolate from Morris, Minnesota.The two isolates gave distinctly different reactions on the populations studied, indicating the presence of pathogenic races. Also, varietal reactions varied somewhat with the environments used in testing.Resistance to the St. Paul isolate, designated race 1, was attributed to a single dominant gene, possessed by the varieties ‘Norchief,’ ‘Harosoy,’ and P.I. 132,207. The proposed symbol for this gene is Rpg1. The inheritance of resistance to the Morris isolate, race 2, appeared to involve more than one gene. Delineation of detail, however, must await further study.
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