Purpose: This study assessed the survival capabilities of Salmonella in dry turkey manure particles (of a size capable of being airborne) when present on spinach leaves, as well as effect of UV radiation on that survival.
Methods: Turkey manure dust (125 μm) at 5% moisture level inoculated with a cocktail of Salmonella was lightly dusted onto spinach leaves under growth chamber conditions and survival monitored over 21 days. Effect of UV light on survival was factored into the experimental design such that the abaxial and adaxial sides of the leaves were compared for Salmonella survival. Treatment controls consisted of plants grown under UV filter. Outcomes were compared with trials where plants were inoculated with Salmonella via aerosol spray. Survival curves were generated and transformed data analyzed using SAS.
Results: Under UV light, particulate manure dust significantly (P < 0.05) reduced Salmonella inactivation on spinach leaves. Deposition site on leaves also influenced survival as Salmonella survived preferentially (P < 0.05) on the abaxial surface. By day 7 post-inoculation, Salmonella cells in manure dust on leaves had achieved only a 2 log reduction, while population in control samples declined by approximately 5 logs. By day 14, recovery of viable Salmonella from abaxial and adaxial leaf surfaces was 33% (n = 6) versus 0% respectively on XLD agar.
Significance: This research supports the hypothesis that dust generated from poultry manure increases the likelihood that Salmonella can persist on leafy green surfaces, especially in arid areas where unintended aerosolization could frequently occur.