Bacteriophage have been proposed as an alternative to pesticides to kill bacterial pathogens of crops. However, phage-biocontrol outcomes are still highly variable and poorly understood in natural rhizosphere microbiomes at timescales considering both ecological and evolutionary processes. However, the efficacy of phage-biocontrol is variable and poorly understood in natural rhizosphere microbiomes at timescales considering both ecological and evolutionary processes. We studied the biocontrol efficacy of different phage combinations on Ralstonia solanacearum infection in tomato. Increasing the number of phages in combinations decreased disease incidence by up to 80% in greenhouse and field experiments during single crop season. Disease reduction was explained by pathogen density reduction and selection for resistant but slow-growing pathogen strains, together with enrichment for bacterial species that were antagonistic towards Ralstonia solanacearum. Phage treatment did not affect existing rhizosphere microbiota. Specific phage combinations show promise as precision tools to reduce pathogen abundance in plants.

Spreadsheet tabs contain data underlying figures from the associated paper (http://doi.org/10.1038/s41587-019-0328-3)