Bacterial compositions effective for inhibiting fungal diseases of potatoes and/or potato sprouting are produced by co-culture of two or more of Pseudomonas fluorescens (NRRL B-21133), Pseudomonas fluorescens biovar (NRRL B-21053), Pseudomonas fluorescens (NRRL B-21102) and Enterobacter cloacae (NRRL B-21050). Compositions produced by co-culture of these bacteria together in the same culture medium are significantly more effective for inhibiting fungi-induced diseases of potatoes and/or inhibiting sprouting of potatoes, than blends or mixtures of the same bacteria cultured separately.