Florida Department of Agriculture - Agricultural Marketing ...

FLORIDA DEPARTMENT OF AGRICULTURE AND CONSUMER SERVICES

Final Performance Report

2014 Specialty Crop Block Grant Program USDA AMS Agreement Number:14-SCBGP-FL-0012

Total Grant Funds Awarded - $4,579,401.97

State Contact Joshua M. Johnson Program Administrator Florida Department of Agriculture and Consumer Services 407 South Calhoun Street, M9 Tallahassee, Florida 32399-0800 (850) 617-7340 SpecialtyCrop@

Project (1): T-GAPs optimization for the reduction of Salmonella risk in Florida tomatoes

Project Partners: University of Florida

Project Summary

The over-arching goal of this proposed work is to improve microbiological safety of Florida tomatoes and to define a combination of straightforward practices to that end. The achievement of a significant improvement in the microbiological safety of tomatoes will require a comprehensive approach that combines plant breeding, manipulation of the fertilization regime, and promoting targeted education. Such a comprehensive approach to microbiological safety of tomatoes will cut across biological and social sciences, all while remaining one project with a single over-arching goal. The rationale for this proposal is based on our discoveries of 10-100 differences in the susceptibility of different cultivars of tomatoes to post-harvest contamination with Salmonella and the fact that the physiological changes in tomatoes that are associated with maturity dramatically affect the ability of Salmonella to proliferate in tomatoes. Furthermore, with previous funding from SCRI, we learned that proliferation of Salmonella in tomatoes linearly correlated with the levels of nitrogen in tomato leaf tissues and sap (corresponding to the different fertilization regimes), but these effects were cultivar- and maturity-dependent. While contributions of several other individual factors (fertilization and irrigation regimes, phyto-pathogen management, and cultivar selection) to tomato safety outcomes are known, it is not yet clear how these factors interact to affect produce safety. These observations give us a realistic expectation of finding the combination of practices, which ? without dramatically changing production conditions, or reducing the yield or increasing the cost of production ? will promote safety of vegetables at all production scales. Furthermore, these analyses will establish which production practices (especially those that are timeconsuming and expensive) are inconsequential to the produce safety outcomes. Such optimization of production practices is the goal of this research team and our partners and will have immediate benefits to the industry.

This project is timely because Florida is the nation's leader in the production of fresh tomatoes, especially in Spring and Fall seasons. Based on USDA ERS data, fresh market tomatoes comprise about 40% of Florida's fresh market vegetable cash receipts. Outbreaks of gastrointestinal illness linked to fresh produce are tremendously damaging to the producers.

The issues of food safety represent the greatest threat to sustainability and profitability of Florida tomato industry. Based on USDA ERS data, following the June-August 2008 outbreak of salmonellosis caused by S. enterica sv. St. Paul (which was initially wrongly blamed on tomatoes from Florida) the price of tomatoes at the point of first sale dropped from 56.8 cents/lb in June to 25.6 cents/lb in August.

This nearly obliterated Florida tomato industry. Even though there were no major outbreaks of salmonellosis linked to Florida tomatoes over the last two years, over 19,500 lbs of tomatoes (packed by a Florida packer and distributed to 6 states) were recalled due to Salmonella contamination in February 2014 (). Promoting microbiological safety of Florida produce will help maintain its competitiveness on the domestic and international markets. This will benefit millions of Florida consumers, tens of thousands farmers, packers and retailers.

Project Approach

The work plan to achieve Goal 1 was divided into two overlapping phases:

Phase 1. Meta-analysis of the data obtained by the collaborating research groups

Phase 2. Field validation of the data

Meta-analysis was performed with regression trees to identify the field production conditions that were best able to explain the observed variation in Salmonella proliferation in post-harvest tomatoes. The analysis combined, compared, and contrasted results from three different studies conducted by our groups in order to identify patterns among tomato production practices and their contribution to the microbiological safety of tomatoes. These included data sets on the effect of three levels of irrigation (in three different seasons, in two locations in Florida for two tomato cultivars), 9 fertilization levels (3 levels of potassium x 3 levels of nitrogen, in three seasons in two locations for two cultivars), and the effects of foliar sprays with Fe and Cu. These data were originally obtained in separate experiments, some conducted with previous funding from FDACS and from other industry groups. The main outcome of this meta-analysis is that fertilization and irrigation regimes, as well as Cu and Fe, do not seem to have a significant consistent impact on the microbiological safety outcomes for tomatoes. This is important because it frees up producers from optimizing these parameters to maintain both yields and microbiological safety of the product.

In contrast, we determined that tomato maturity at harvest and weather conditions at (or within a few days prior to) harvest have the most significant impacts on the microbiological safety of tomatoes. Specifically, red ripe tomatoes were significantly and consistently more conducive to the proliferation of Salmonella. In addition, tomatoes harvested in the driest, sunniest season were the most conducive to post-harvest proliferation of the pathogen. To follow up on the field data and validate field observations, we determined the effects of relative humidity pre-harvest on proliferation of Salmonella in tomatoes post-harvest. The lab experiments confirmed that high humidity pre-harvest decreased the potential Salmonella proliferation, likely related to the presence of native microbiota. When tomatoes were surface disinfected prior to the humidity treatment (and thus lost their native microbiota) they supported the same levels of Salmonella proliferation regardless of humidity level.

The work plan to achieve Goal 2 was performed as the third phase of the project:

Phase 3. Outreach to the stakeholders

Ten educational videos (5 in English and 5 in Spanish) were developed, recorded, edited and published. The goal of these videos was to provide guidance on how to investigate outbreaks of food- or waterborne illnesses. The first video deals with the epidemiological survey, the second video focuses on culture-based detection of pathogens, and the following videos focus on molecular approaches (nucleic acid-based, immunological and fingerprinting). These videos are publicly available on Youtube: As of October 2017, the videos have been watched a total of 594 times (290 for English language versions, 304 for Spanish language versions).

The following presentations/workshops/training sessions were conducted: 1) Of mice and men... and tomatoes: comparative and functional genomics of Salmonella's alternate lifestyles. USDA-ARS Western Regional Research Center, May 6, 2016. Albany, CA. Attended by 12 USDA employees.

2) Of mice and men... and tomatoes: comparative and functional genomics of Salmonella's alternate lifestyles. UC Davis Post-harvest Physiology Group. May 5, 2016. Davis, CA. Attended by 10 graduate students and technicians.

3) An avirulent Salmonella surrogate strain: construction, validation and potential uses. 2016 Florida Association for Food Protection Annual Education Conference. May 11-13, 2016. Crystal River, FL. Attended by 45 industry scientists and managers.

In addition, two UF IFAS EDIS factsheets (in English and Spanish) regarding the results of the metaanalysis were developed and are freely available on the internet. "Impact of Tomato Varieties and Maturity State on Susceptibility of Tomatoes to Salmonella" English: Number of times downloaded: 2015 - 613; 2016 - 228; 2017 - 294; total (2015-2017): 1135 Spanish: Number of times downloaded: 2015 - 502; 2016 - 270; 2017 - 286; total (2015-2017): 1058 "The Role of Crop Production Practices and Weather Conditions in Microbiological Safety of Tomatoes and Peppers" English: Number of times downloaded: 2015 - 594; 2016 - 424; 2017 - 406; total (2015-2017): 1424

Spanish: Number of times downloaded: 2015 - 445; 2016 - 318; 2017 - 221; total (2015-2017): 984

Goals and Outcomes Achieved

Goal 1: Develop scientifically-based recommendations on improving microbiological safety of tomatoes by optimizing pre-harvest production conditions (e.g. macro- and micro-nutrient fertilization, irrigation regime, cultivar selection, maturity at harvest and environmental conditions at harvest). Performance Measure: In year 1, we will develop a model that links pre-harvest production practices with susceptibility to Salmonella based on the meta-analysis of the data collected by the co-PIs over the last 5 years. In year 2, we will validate the model in the field. Benchmark: Currently, in market tomatoes, Salmonella numbers can proliferate by 10^5 fold within a week. Target: Increase resistance of tomatoes to Salmonella by at least 10-fold through the optimization of pre-harvest production practices.

Actual accomplishments for Goal 1: The meta-analysis revealed that high relative humidity in the week before harvest decreased proliferation of Salmonella 10 to 100-fold in tomatoes post-harvest. The target for Goal 1 was met.

Goal 2: Promote microbiological safety of tomatoes through on-site and web-based training. Performance Measure: Number of tomato growers that intend to adopt workshop recommendations. Benchmark: None. Target: Eighty percent (120) of the 150 participants in two on-site training workshops in tomato-growing regions around the state will demonstrate intent to implement recommendations on modifying production practices to improve microbiological safety of tomatoes.

Actual accomplishments for Goal 2: With the unanticipated staffing turnover at the beginning of this project (Dr. Marvasi accepted a faculty position in Europe), the two large training workshops were not conducted as originally planned. Instead, three smaller presentations with a total of 67 attendees were conducted without collecting the metrics needed for the target. In lieu of the original target, the high number of views (approximately 600 total, and growing) for the English and Spanish language training videos on YouTube provides evidence for the extent of the outreach efforts. The continued access of these videos and of the EDIS factsheets () demonstrates that stakeholders are seeking and finding these resources online.

Beneficiaries

The meta-analysis performed during this project provides straight-forward, science-directed solutions to reduce the risk of Salmonella in post-harvest tomatoes consumed fresh by consumers across the nation. This information was distributed through peer-reviewed publications, EDIS factsheets, and through YouTube training videos. The beneficiaries of this information include:

1) Consumers in Florida and nationwide, where Florida tomatoes are sold

Based on the USDA ERS data, tomato is the most consumed fresh vegetable: in 2009, Americans purchased > 18 lbs. of fresh tomatoes per capita. Florida ranks first (or second, depending on the metric) nationally in the acreage, production, and value of fresh market tomato. This project provides sciencebacked solutions to ensure the continued safety of fresh tomatoes for consumers.

2) Producers, farmers, and packers

Over 31,5000 acres are under cultivation for the fresh tomato market in Florida based on USDA ERS data. Even though Florida tomatoes haven't been linked to a major outbreak of human illness in at least several years, these outbreaks, when they occur, could be very costly. For example, the Salmonella St. Paul outbreak in 2008 caused over $100 million in damage to Florida tomato industry. Losses from the California Spinach outbreak in 2006 were estimated at $3,500/acre. Producers and farmers will have an opportunity to optimize production practices, in particular the timing of harvests with respect to rain events, to further reduce the risk of outbreaks.

All told, the 2012 USDA Census of Agriculture counts 565 operations with area harvested for tomatoes grown in the open. Improvements to state TGAP regulations will benefit all of these operations.

Lessons Learned

One of the most important lessons learned from this project is that fertilization and irrigation regimes, as well as Cu and Fe application, do not seem to have a consistent impact on the microbiological safety outcomes for tomatoes. This is important because it frees up producers from optimizing these parameters to maintain both yields and microbiological safety of the product. In addition, we changed

our work plan to focus on simulating environmental conditions (temperature, humidity, etc) under the laboratory and/or greenhouse conditions, rather than field experiments since our meta-analysis revealed that irrigation, fertilization, or spraying regimes do not have an impact on the susceptibility of tomatoes to post-harvest contamination with Salmonella. Rather, the most consistently effective method for reducing Salmonella in post-harvest tomatoes was to harvest less mature fruits and/or harvest tomatoes when relative humidity is high, which was confirmed with laboratory experiments.

Contact Person

Julie Meyer (352) 273-8195 juliemeyer@ufl.edu

Funding Expended: $58,294.58

Project (2): Sustainable Phosphorus Management for Potato Production in Northeast Florida

Project Partners: University of Florida Board of Trustees

Project Summary

The Hastings area belongs to St. Johns River Watershed and has the largest river in the state. This area is also the potato capital of Florida and has approximately 21,000 acres used for potato production. Phosphorus management is most important to protect water bodies from pollution because P is the key nutrient responsible for algal bloom. Soils used for potato production in the area have low pH that serves to protect potato tubers from infection of common scab diseases. However, at low soil pH, soil aluminum and/or other metals is active and can tie P up, limiting the bioavailability of P in the soil. This limitation results in P application greater than the UF/IFAS recommendation (Vegetable Production Handbook of Florida, 2017-2018, Liu et al. 2017).

The purpose of this project was to enhance the sustainability of potato production and the environment through increasing potato growers' awareness about optimizing P management practices. Our surveys of the 32 potato farms revealed that the extractable P levels of the soils were up to 600 ppm, which is approximately 15 times greater than the UF/IFAS recommendation for potato production. In 2012, the research team's P-rate trial on soil with 170 ppm extractable P showed positive yield response: 136, 239, 270, and 280 cwt/acre for 0, 50, 75, and 100 lb/acre P2O5, respectively. Only the two greatest P-rates were not significantly different in tuber yields (Zotarelli, 2013, research report). Based on the UF/IFAS recommendation, no P-fertilizer should have been applied to the soil for potato production in the area. This yield response to P fertilizer application on P-rich soils indicates that the IFAS recommendation may need to be adjusted in the Hastings area. These positive yield responses to P fertilization may be likely related to high levels of extractable aluminum, calcium or other metals in soils in the area.

Project Approach

This project was performed in field trials with chipping potato, 'Atlantic' (2015 through 2017) on the UF/IFAS Hastings Agricultural Extension Center (HAEC) and with tablestock potato, 'Yellow Star' (2015) and 'Fabula' (2016 and 2017) on a private potato farm in the Hastings area for three growing seasons. There were six P rates and two gypsum rates totaling 12 treatments on the HAEC, and six P rates and three gypsum rates totaling 18 treatments on the private farm in 2015. The data in 2015 showed that soil pH was low at 4.8. A lime treatment of 2 t/acre lime was added to the trials at either location for both 2016 and 2017 growing seasons. During the three growing seasons, 13,200 leaves were measured for leaf greenness, 1,824 plant tissue samples for biomass and P, K, Ca, and Mg contents, 1,482 soil samples for extractable P and Ca, pH, CEC, 152 samples for P fractionation, 608 tuber samples for external, internal and specific gravity, and 632 samples for tuber yield. The farms with the trials had extractable nutrients of 300 to 400 ppm P, 150 to 200 ppm K, 900 to 1,300 ppm Ca, and 100 to 120 ppm Mg in soil. Soil pH ranged from 4.8 to 5.8, occasionally to 6.3. At this low soil pH, two thirds of soil P

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