P-634 - Applying bacteriophages to reduce bacterial blotch disease in Agaricus bisporus

White button mushroom (Agaricus bisporus) production is negatively affected by brown blotch disease, caused by several Pseudomonas species such as Pseudomonas tolaasii. To mitigate this pathogen, biological control strategies like phage therapy have been explored. Our research demonstrates that phage 1106, isolated from mushroom casing, specifically targets P. tolaasii strain BP1106, highlighting its potential as a biological control agent. To assess its effectiveness against brown blotch disease, two trials were conducted using 48 A. bisporus mushrooms treated with phage 1106 against BP1106, n = 3 replicates per treatment. The culturable population levels were examined for four consecutive days by extracting the inoculated tissue from the mushrooms, homogenizing it, and dilution plating it in King’s B media, ammended with novobiocin, penicillin, and cyclohexamide. Similarly, the phage population dynamics were evaluated over four days using plaque assays. Disease progression on the mushrooms was assessed from day 1 to day 3 using a scale from 0 to 3, where 0 indicated no disease and 3 represented deep pitting, black spots, and larger infection sites. In both trials, the treatment amended with phage 1106 significantly reduced the bacterial population levels (P < 0.01) and disease progress (P < 0.01) compared to the negative control. In addition, phage 1106 was recovered from inoculated samples throughout the trial. These results suggest that the phage tested has biocontrol potential against bacterial blotch caused by P. tolaasii strain BP1106 in white button mushrooms.