Resistance of Bradyrhizobium japonicum strains to different fungicides and herbicides

Abstract

Of 50 strains ofB. japonicum, 64%, 44% and 54% were resistant to the fungicides captan, pentachloronitrobenzene and tetramethylthiuram disulphate, respectively, at concentrations above those recommended for treatment of soybeans. 100% and 84% of the strains were resistant to the herbicides trifluralin and metribuzin, respectively, also at concentrations above those recommended for soybeans. No strain was resistant to alachlor above 3.5 μg/ml but 40% were sensitive to 2.5 μg/ml, these being, respectively, the maximum and minimum concentrations recommended for soybeans.