Effects of fumigation on the reduction of Salmonella enterica in soil

Authors: Gu, Ganyu; MURPHY, CLAIRE - Virginia Tech; ZHENG, JIE - Food And Drug Administration(FDA); Nou, Xiangwu; RIDEOUT, STEVEN - Virginia Tech; STRAWN, LAURA - Virginia Tech

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2023
Publication Date: 9/22/2023
Citation: Gu, G., Murphy, C., Zheng, J., Nou, X., Rideout, S., Strawn, L. 2023. Effects of fumigation on the reduction of Salmonella enterica in soil. Foodborne Pathogens and Disease. https://doi.org/10.1089/fpd.2023.0031.
DOI: https://doi.org/10.1089/fpd.2023.0031

Interpretive Summary: Soil with biological amendments has been reported as one possible source of contamination of foodborne pathogens during vegetable crop production; however, little is known about the effective method to mitigate Salmonella contamination in agricultural soil. In a collaborative research with VT and FDA, we evaluated the impacts of methyl bromide alternative fumigates on Salmonella reduction in soil. Results derived from this study indicated that fumigation using 1,3-dichloropropene and dimethyl disulfide, which labelled for plant pathogen management, can also benefit the decontamination of Salmonella in agricultural soil. This study provides additional insight into the integrated pest management strategies with fumigation to control both plant and foodborne pathogens during produce production at the preharvest level.

Technical Abstract: Due to the phaseout of methyl bromide, there is a need for broad-spectrum soil fumigation alternatives. However, little is known about the impact of fumigation alternatives on foodborne pathogens typically found in the soil environment, such as Salmonella. This study investigated the effect of methyl bromide alternative fumigates on Salmonella reduction in soil. Sandy loam soils were collected from conventional vegetable fields and inoculated with either Salmonella enterica Newport J1892 or Typhimurium ATCC 14028 (5.9 ± 0.3 log CFU/g). Each of four fumigants labeled for plant pathogen management (1,3-dichloropropene, chloropicrin, dimethyl disulfide, and metam sodium) was applied at equivalent maximum application levels in the field and left for a 2-week fumigation period. Sterile water was used as a control. Following the fumigation period, Salmonella concentrations in soil samples were enumerated on 1, 7, 14, and 21d post-fumigation. The mean population of S. Newport was significantly higher than that of S. Typhimurium 1d after fumigation (p = 0.0153). Fumigation using 1,3-dichloropropene or dimethyl disulfide significantly reduced S. Newport and S. Typhimurium populations compared to the control. The rate of Salmonella reduction (log/day) in soils treated with dimethyl disulfide was higher than that with the other treatments. Results suggested that alternative fumigation treatments did not facilitate Salmonella survival and thus might assist in mitigating the risk associated with Salmonella in soil environments.