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Pre-harvest contamination sources investigated in recent fresh produce illness outbreaks include soil, irrigation/flood water, manure, wildlife vectors, plants, harvesting equipment, and worker practices. Soil amendments and composts are now also being implicated. Market pressures are mounting for other regions to adopt a recently developed California field practice audit system for fresh produce. The reliability and interpretation of microbial metrics for soil, water, and soil amendments for this pre-harvest audit system needs to be evaluated for use in the Delmarva region where poultry rather than dairy/cattle operations share the agricultural landscape with fresh produce growers. <P>This project focuses on two issues: 1) comparative evaluation of field practice audit criteria or metrics as applied to produce and environmental samples from the Delmarva region and 2) evaluation of pathogen reduction efficacy in minimally-managed poultry litter composting. <P>The UMES and USDA each will conduct the experimental poultry manure composting and pathogen destruction trials as well as microbiological assays of experimental and on-farm environmental and produce samples. Fresh produce growers in Maryland will provide access to several production fields for cross-seasonal environmental and produce sampling. This project complements and expands the regional coverage of current USDA-ARS study sites focusing on microbial ecology of food safety and water quality in fresh produce. The UMES faculty and students will work closely with the USDA-ARS and Delaware State University collaborators in conducting the research, and preparing publications and communications of research results to grower communities and other stakeholders. Growers will review and suggest how results might be used to help them meet marketing expectations and apply good agricultural practices (GAPs).
NON-TECHNICAL SUMMARY: Certain agricultural practices contribute to contamination of fresh produce with harmful microorganisms. Reliability and interpretation of microbial metrics for soil, water, and soil amendments for pre-harvest audit system needs to be evaluated for use in the Delmarva region where poultry and fresh produce operations are common. This project will 1) compare field practice audit criteria/metrics as applied to produce and environmental samples from the Delmarva region and 2) evaluate pathogen reduction efficacy in minimally managed poultry litter composting.
<P>APPROACH: (1) Occurrence and Persistence of Salmonella and E. coli (commensal and O157:H7) on produce and in grower fields a. Determine the seasonal prevalence, occurrence, and persistence of Salmonella and E. coli (commensal and O157:H7) in selected commercial fresh produce fields in conjunction with GAPs guidelines using WGA methods and those developed by USDA-ARS in related research projects. (2) Irrigation water a. Compare the occurrence and quantities of generic and toxigenic E. coli recovered from irrigation and other source waters associated with crop irrigation in the Delmarva region. (3) Animal manure-containing soil amendments a. Determine the quantity of E. coli (commensal and toxigenic) and salmonellae in minimally managed poultry litter compost and commercially available composts using rapid, sensitive microbial methods. b. Determine the efficacy of a modified composting regimen; know as minimally-managed composting, on pathogen destruction in poultry litter prior to its being spread on agricultural fields. (4) Provide comprehensive outreach and technical training to area produce growers and others in Good Agricultural Practices related to safe produce handling from farm to plate.