Browsing by Author "Bardsley, Cameron"

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    Assessing On-Farm Produce Safety Risks: General Practices
    Understanding on-farm produce safety risks is essential for all farms who grow, harvest, pack, hold and/or ship fruits and vegetables. Assessing the general practices of a farm operation is the second step to developing and implementing best practices to reduce those risks and reduce potential produce contamination. This publication is the second in a series of seven factsheets to assist farmers in creating a food safety program
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    Assessing On-Farm Produce Safety Risks: Harvest Stage
    Understanding on-farm produce safety risks are essential for all farms who grow, pack, harvest, hold and/or ship fruits and vegetables. Identifying risks that may be associated on the farm during the harvest stage, is the fifth step to developing and implementing best practices to reduce those risks and reduce potential produce contamination. This publication is the fifth in a series of six publications to assist the industry in creating a food safety program
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    Assessing On-Farm Produce Safety Risks: Performing a Hazard Analysis
    Bardsley, Cameron; Vallotton, Amber; Edwards, Ashley; Strawn, Laura K. (2021)
    Understanding on-farm produce safety risks is essential for all farms who grow, harvest, pack, hold and/or ship fruits and vegetables. The first step to developing and implementing best practices to reduce risks and reduce potential produce contamination is to perform a hazard analysis, where producers identify risks that may be associated on their farm. This publication is the first in a series of seven factsheets to assist farmers in creating a food safety program
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    Assessing On-Farm Produce Safety Risks: Post-Harvest Handling Stage
    Understanding on-farm produce safety risks are essential for all farms who grow, pack, harvest, hold and/or ship fruits and vegetables. Developing and implementing best practices to reduce risks and reduce potential produce contamination during the post-harvest handling stage is critical. This publication is the sixth in a series of seven factsheet publications to assist farmers in creating a food safety program.
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    Assessing On-Farm Produce Safety Risks: Pre-Plant Stage
    Understanding on-farm produce safety risks is essential for all farms who grow, harvest, pack, hold and/or ship fruits and vegetables. Identifying risks that may be associated on the farm during the pre-plant stage is the third step to developing and implementing best practices to reduce those risks and reduce potential produce contamination. This publication is the third in a series of seven factsheets to assist farmers in creating a food safety program
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    Assessing On-Farm Produce Safety Risks: Preparing for GAP Certification
    Understanding on-farm produce safety risks is essential for all farms who grow, harvest, pack, hold and/or ship fruits and vegetables. After a farmer has developed and implemented best practices to reduce risks and contamination during each stage, they are ready to prepare for a GAP audit and certification. This publication is the seventh in a series of seven factsheets to assist farmers in creating a food safety program.
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    Assessing On-Farm Produce Safety Risks: Production Stage
    Understanding on-farm produce safety risks are essential for all farms who grow, harvest, pack, hold and/or ship fruits and vegetables. Identifying risks that may be associated on the farm during the production stage is the fourth step to developing and implementing best practices to reduce those risks and reduce potential produce contamination. This publication is the fourth in a series of seven factsheet publications to assist farmers in creating a food safety program
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    Demystifying Agricultural Production Water Testing under the FSMA Produce Safety Rule
    Strawn, Laura K.; Vallotton, Amber; Boyer, Renee R.; Bardsley, Cameron (Virginia Cooperative Extension, 2019-09-10)
    Discusses testing of water that will be used for cleaning harvested crops.
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    Factors Influencing Salmonella Survival in Agricultural Soils and Internalization through Solanaceous Crop Roots
    Bardsley, Cameron (Virginia Tech, 2020-04-28)
    Solanaceous crops such as peppers and more commonly tomatoes have been linked to Salmonella outbreaks that have occurred in the United States. The source of contamination for some of these outbreaks was traced back to the preharvest environment. Sources of contamination at the preharvest level of production often include irrigation water, soil, and the use of biological soil amendments of animal origin (BSAAO). This dissertation aims to (i) determine how factors such as the use of BSAAO's, Salmonella strain, soil type, and irrigation influence the survival of Salmonella in agricultural soils and (ii) determine the risk of Salmonella internalization in to transplanted solanaceous crops (tomatoes and bell peppers) and identify factors that influence internalization through the roots such as mode of contamination, soil contamination level, and root damage. Sandy loam (SL) and clay loam (CL) soils both unamended and amended with poultry litter (PL), irrigated either daily or weekly were inoculated with one of twelve strains of Salmonella enterica and monitored for growth and survival until no longer detected. Tomato plants were transplanted into one of three contamination treatments: contaminated soil (A) or irrigation water administered either once (B, single exposure event) or for 7 d following transplantation (C, repeated exposure event). Plants were sampled 1, 2, 3, 7 and 90 d post-transplantation for Salmonella internalization. Pepper plant roots were left intact, damaged, or removed and placed in inoculated water (6.2 log CFU/ml). Pepper plants in the soil contamination study, were transplanted into soil inoculated with Salmonella at different contamination levels (High, Mid, and Low). Samples were collected 1, 2, 3, and 7d post-transplant. Plants were surface sanitized and enumerated for Salmonella internalization by plant section. Strains in soils treated with PL survived significantly (P<0.05) longer (56 and 112 days for SL and CL respectively), than Salmonella strains in unamended soils. In PL amended SL and CL soils, most strains grew significantly (P<0.05) within the first week following inoculation and ranged from 84 to 210 days in the point it was last detected. Strains survival increased significantly (P<0.05) in soil irrigated weekly compared to soils irrigated daily, weekly irrigation increased survival by 140 to 224 and 42 to 168 days in SL and CL soils respectively depending on the strain. Root sections in the tomato plants of treatment A had significantly (P<0.05) higher recovery of Salmonella internalization compared to the other treatments. No tomato fruit sampled were positive for Salmonella internalization. Pepper plants with damaged roots had significantly higher (P<0.05) Salmonella internalization in the stem than plants with intact roots, while plants with no root stalk had significantly higher (P<0.05) Salmonella internalization in the stem and leaves of plants with intact and damaged roots. Pepper plants exposed to high concentrations of Salmonella had significantly more internalization occur in the roots than plants exposed to mid and low concentrations of Salmonella. Due to the results of these studies assessing the risk of using PL and irrigation regime should be considered in the Salmonella growth and survival in agricultural soils. Though it is unlikely, steps should be considered to limit Salmonella contamination of soil and irrigation water and root damage to prevent the internalization of Salmonella in tomato and bell pepper plants through intervention measures such as composting, water treatment, and effective transplanting techniques.
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    Strain, Soil-Type, Irrigation Regimen, and Poultry Litter Influence Salmonella Survival and Die-off in Agricultural Soils
    Bardsley, Cameron; Weller, Daniel L.; Ingram, David T.; Chen, Yuhuan; Oryang, David O.; Rideout, Steven L.; Strawn, Laura K. (2021-03-16)
    The use of untreated biological soil amendments of animal origin (BSAAO) have been identified as one potential mechanism for the dissemination and persistence of Salmonella in the produce growing environment. Data on factors influencing Salmonella concentration in amended soils are therefore needed. The objectives here were to (i) compare die-off between 12 Salmonella strains following inoculation in amended soil and (ii) characterize any significant effects associated with soil-type, irrigation regimen, and amendment on Salmonella survival and die-off. Three greenhouse trials were performed using a randomized complete block design. Each strain (similar to 4 log CFU/g) was homogenized with amended or non-amended sandy-loam or clay-loam soil. Salmonella levels were enumerated In 25 g samples 0, 0.167 (4 h), 1,2, 4, 7, 10, 14, 21,28, 56, 84, 112, 168, 210, 252, and 336 days post-inoculation (dpi), or until two consecutive samples were enrichment negative. Regression analysis was performed between strain, soil-type, Irrigation, and (i) time to last detect (survival) and (li) concentration at each time-point (die-off rate). Similar effects of strain, irrigation, soil-type, and amendment were identified using the survival and die-off models. Strain explained up to 18% of the variance in survival, and up to 19% of variance In die-off rate. On average Salmonella survived for 129 days in amended soils, however, Salmonella survived, on average, 30 days longer In clay-loam soils than sandy-loam soils [95% Confidence interval (Cl) = 45, 15], with survival time ranging from 84 to 210 days for the individual strains during dally irrigation. When strain- specific associations were investigated using regression trees, S. Javiana and S. Saintpaul were found to survive longer In sandy-loam soil, whereas most of the other strains survived longer In clay-loam soil. Salmonella also survived, on average, 128 days longer when irrigated weekly, compared to daily (Cl = 101, 154), and 89 days longer in amended soils, than non-amended soils (Cl = 61,116). Overall, this study provides insight into Salmonella survival following contamination of field soils by BSAAO. Specifically, Salmonella survival may be strain- specific as affected by both soil characteristics and management practices. These data can assist in risk assessment and strain selection for use in challenge and validation studies.