Treatment Persistence and Resistance Monitoring in Bacteriophage Control of Bacterial Plant Diseases

Abstract

Bacterial plant diseases reduce crop quality and threaten food production. Bacteriophages are viruses that infect bacteria and may support disease management. Their value depends on two linked questions. First, do active phages remain where protection is needed? Second, do target bacteria remain sensitive after exposure? This narrative review examines published experiments on phage persistence and bacterial resistance in plant disease control. It draws on studies involving tomato, rice, apple, pear, and cherry. The evidence includes laboratory work, plant experiments, and orchard trials. Tomato studies show that sunlight can shorten phage survival on leaf surfaces. Protective formulations improved persistence in some experiments, although benefits varied across plant systems. A rice experiment found smaller lesions after phage treatment than in untreated plants. An apple study reported disease reductions that differed greatly among locations and years. In cherry orchards, phages remained detectable longer when the bacterial host was present. However, detection did not ensure lasting bacterial suppression. Resistance findings also depended on the experimental setting. One tomato study found frequent resistance in laboratory cultures but little evidence of its emergence inside leaves. Other work documented existing variation and cross-resistance among fire blight bacteria. These results support joint assessment of phage activity, bacterial sensitivity, and disease outcomes. They also show that laboratory findings cannot predict field performance alone. More long-term, multi-location studies are needed before reliable predictions can be made across crops.