Exploration of Phage–Agrochemical Interaction Based on a Novel Potent Phage LPRS20-Targeting <i>Ralstonia solanacearum</i>

Phage therapy has the potential to alleviate plant bacterial wilt. However, the knowledge gap concerning the phage-agrochemical interaction impedes the broader application of phages in agriculture. This study characterized a phage isolate and investigated its interactions with agrochemicals. A novel species within the <i>Ampunavirus</i> genus was proposed, serving phage LPRS20 as a type phage with a broad lytic range and significant antibacterial activity against <i>Ralstonia solanacearum</i> strains infecting tobacco, chili, or tomato. Sensory evaluation of the morphology of tobacco leaves suggested that phage application resulted in negligible harm to plants. Investigations into phage-agrochemical interactions revealed synergisms when LPRS20 was delivered 4 h before thiodiazole-copper as well as LPRS20 in combination with low-concentration berberine. Overall, our findings reveal that phage LPRS20 represents a novel, effective, and eco-friendly biocontrol agent against tobacco bacterial wilt <i>in vivo</i> and <i>in vitro</i> and contributes to the potential integration of phages and agrochemicals for controlling soil-borne pathogens.