Abstract: This invention relates to Rhizobium strains having good infecting and nitrogen-fixing characteristics and which are resistant to fungicides. These strains are produced by cultivating a Rhizobium strain sensitive to a particular fungicide in the presence of an amount of the fungicide, and for a time less than that sufficient to kill the entire Rhizobium population but sufficient to kill a majority of the population. The remaining Rhizobium population is isolated and recultured in the presence of an increased amount of the fungicide, again an amount and a time less than sufficient to kill the entire Rhizobium population, but sufficient to kill a majority of the population. This procedure is repeated for sufficient passages, with increasing amounts of said fungicide, to provide a Rhizobium strain sufficiently resistant to said fungicide so that the Rhizobium strain multiplies and enters into a nitrogen-fixing symbiosis in the presence of agriculturally effective amounts of the fungicide.

Abstract: This invention relates to Rhizobium strains having good infecting and nitrogen-fixing characteristics and which are resistant to fungicides. These strains are produced by cultivating a Rhizobium strain sensitive to a particular fungicide in the presence of an amount of the fungicide, and for a time less than that sufficient to kill the entire Rhizobium population, but sufficient to kill a majority of the population. The remaining Rhizobium population is isolated and recultured in the presence of an increased amount of the fungicide, again an amount and a time less than sufficient to kill the entire Rhizobium population, but sufficient to kill a majority of the population. This procedure is repeated for sufficient passages, with increasing amounts of said fungicide, to provide a Rhizobium strain sufficiently resistant to said fungicide so that the Rhizobium strain multiplies and enters into a nitrogen-fixing symbiosis in the presence of agriculturally effective amounts of the fungicide.