Antifungal activity against Rhizoctonia solani was achieved in vivo through the application of Pseudomonas fluorescens strain 134 encapsulated in sodium alginate beads of different sizes (0.5, 1, and 2 mm). The activity was compared to that obtainable with chemical treatments and bead-derived liquid formulations. The latter was obtained by dissolving alginate beads of 1 and 0.5 mm in 1% Na-citrate solution before application, without any significant (P < 0.05) reduction of bacterial numbers during the dissolution process. The dry bead formulations were applied next to the seeds in plant inoculation experiments, resulting in a reduction of disease symptoms, which were markedly reduced when the liquid formulation was applied. Moreover, the rate of disease symptoms related to liquid formulations from both 1 and 0.5 mm beads was comparable (near to 10%) to that of chemical treatment. Pseudomonas fluorescens strain 134 delivered as both dry and liquid formulations was able to colonize cotton root at a population density of about 10(8) CFU/g fresh root, 15 days after sowing.