In the face of global human population increases, there is a need for efficacious integrated pest management strategies to improve agricultural production and increase sustainable food production. To counteract significant food loses in crop production, novel, safe and efficacious measures should be tested against bacterial pathogens. Pectobacteriaceae species are one of the causative agents of the bacterial rot of onions ultimately leading to crop losses due to ineffective control measures against these pathogens. Therefore, the aim of this study was to isolate and characterize bacteriophages which could be formulated in a cocktail and implemented in planta under natural environmental conditions. Transmission electron microscopy (TEM) and genome analysis revealed Siphoviridae and Podoviridae family bacteriophages. To test the protective effect of a formulated phage cocktail against soft rot disease, three years of field trials were performed, using three different methods of treatment application. This is the first study to show the application of a phage cocktail containing Podoviridae and Siphoviridae bacteriophages capable of protecting onions against soft rot in field conditions.

Ash dieback, caused by the fungus Hymenoscyphus fraxineus, continues to threaten European ash (Fraxinus excelsior), yet the contribution of the leaf microbiome to disease severity remains poorly understood. We surveyed 133 ash trees across nine sites in Northern Ireland, using canopy cover as a proxy for health, and characterised leaf-associated microbial communities using Pacific Biosciences (PacBio) long-read amplicon sequencing (full-length 16S and ITS) and QIIME2-based workflows. Many trees exhibited partial tolerance to ash dieback, with most maintaining stable canopy cover year-on-year, while fewer trees show a decline and a smaller portion showing improvement. Microbial communities were largely stable irrespective of ash health with little difference in alpha diversity (Shannon) or beta diversity (Bray–Curtis PERMANOVA) for either bacteria or fungi. Differential abundance and correlation analyses showed that H. fraxineus was, as expected, negatively associated with canopy cover. Only one fungal species, Papiliotrema flavescens, demonstrated a strong positive association with healthier trees, consistent with previous findings. These results indicate that Northern Ireland hosts a reservoir of ash trees displaying tolerance to ash dieback. While the leaf microbiome does not appear to drive this tolerance at the community level, one fungus, P. flavescens, was correlated with healthier ash.