Summary of Awards to Date

Sources and mechanisms of transfer of Salmonella in the production and postharvest tree nut environment.


Jan. 1, 2012 - Feb. 28, 2014

Award Number


Amount Awarded



Linda J. Harris, Ph.D.
University of California, Davis


M. Jay-Russell



Over the past decade, contamination of nuts with Salmonella has led to numerous recalls and two outbreaks in the U.S. However, sources of Salmonella in nut production and processing are not well understood. We hypothesize that contamination of almonds and pistachios with Salmonella is facilitated by movement of dusts in orchards and during initial post-harvest handling. We also speculate that airborne dust from animal feeding operations (dairies, feedlots) in close proximity to orchards may play a role in the spread of this pathogen. To test this hypothesis we will work closely with our collaborators in the almond, pistachio, and livestock industries to identify collaborating farms, hulling/shelling (almonds), and hulling/processing (pistachio) facilities. Environmental sampling and microbiological analyses will be used to characterize the microbial composition of bioaerosols and dust originating from livestock operations located in close proximity to almond and pistachio production areas in the California central valley; evaluate movement of microorganisms from livestock operations to nearby almond and pistachio orchards; and evaluate the microbial composition of bioaerosols and dusts at almond hullers/shellers and pistachio hulling facilities. Knowledge gained from this study will be shared with stakeholders to improve good agriculture practices that protect almond and pistachios from Salmonella contamination.