Sub-objective 3.1. Evaluate the persistence of non-bacterial food- and waterborne pathogens (parasites and viruses) on crops, in soil and in decaying vegetative matter and investigate possible routes of contamination through migration of particulate matter or direct contact of contaminated material.

Methods:

• Testing of inactivation efficiency of protozoan oocysts for target parasites Cryptosporidium parvum and Eimeria species as a surrogate for the related Cyclospora cayetanensis.
• Inoculation of plants with oocysts and bacterial pathogens; grown in pots using soils from various growing regions; leaves turned back into the soil.
• Determination of oocyst and bacterial presence until oocysts cannot be detected.
• To evaluate viral survival, samples will be tittered for human norovirus.
• Inoculation of samples with human norovirus fecal specimens and/or human norovirus surrogates like Tulane virus and murine norovirus particles, storing at controlled environmental conditions and testing for survival of virus in specific intervals.
• Four soil types will be used since soil type and interaction of colloids with oocysts or virus particles impact survival.

Expected outcomes:

• Collected data will inform risk-based preventive controls as US growers must determine what to do with embargoed crops.
• Development of metrics for inactivation of parasites and viruses in context of composting strategies to inactivate bacterial pathogens.

Sub-objective 3.2. Identify risks and assess current recommendations for produce growing in contact with the ground (melons, cucumbers), dropping to the ground during cultivation (tomatoes, peppers) or placed onto the ground after harvest but before packing.

Methods:

• US FDA guidance that states crops which are staked or grown off the ground, but touch the ground before harvest (drooping crops), are to be treated the same as crops dropped during harvest.
• Experimental study to assess pathogen transfer potential onto cantaloupe, cucumber, and tomato plants grown across multiple states in the East coast.
• Treatments will consist of fruit either in contact with soil, in contact with plastic mulch, or suspended.

Expected outcomes:

• Generate data on the ability of fruit to internalize pathogens in their growing habitat and determine risk of ground contact in relation to fruit close to the ground.

Sub-objective 3.3. Assess the inputs of fecal contamination and risks of contamination associated with pathogens from animal sources in produce fields, as well as survival and transfer to crops.

Methods:

• Analysis of historic data for characterization and prevalence of pathogens in wildlife in agricultural settings.
• Experimental trials to model wildlife contamination occurrences to assess survival and transfer onto soil and/or crop.

Expected outcomes:

• Data and models will provide useful information to growers evaluating risk of bacterial transfer to crops associated with wildlife intrusion and contamination events that could occur in the field.