Summary of Awards to Date

Agriculture Water Treatment – Southwest Region

Date

Nov. 1, 2019 - Apr. 30, 2021

Funding Agency

Center for Produce Safety

Amount Awarded

$206,305.00

Investigator

Channah Rock, Ph.D.
University of Arizona

Summary

Growers are faced with a myriad of options related to water treatment and/or sanitization with very little guidance on the requirements needed for successful implementation of the treatment option. With limited guidance, water treatment decisions are likely to be unsuccessful and expend both excess time and money without the ultimate outcome of reduction in generic E. coli, Total Coliform bacteria, and potential pathogen loading within a water source and thus little to no reduction in microbiological risk. Additionally, there may be regional and site-specific considerations important for effective water treatment. Grower guidance is needed on water treatment best management practices and monitoring strategies to ensure adequate treatment, attainment of regulatory limits, and ultimately the protection of public health. Research will focus on comparative evaluation of three agricultural water treatment options (PAA, Calcium Hypochlorite, and UV Light) in four produce growing regions of the Southwest (AZ and TX). The overall goal of this proposal is to develop scientific data, which allow produce growers to better manage their use of agriculture water treatments.

Technical Abstract

Recent metrics changes to the Arizona and California Leafy Greens Marketing Agreement(s) (LGMA) now require growers utilizing surface water for overhead irrigation, to treat their water within 21 days of harvest. For many producers, this is the first time that water quality data may indicate the need for antimicrobial treatment of agricultural water as a corrective action before irrigation can be applied safely. Exacerbating these challenges, growers are faced with a myriad of options related to antimicrobial water treatment with very little guidance on the most appropriate treatment option for their ranch, or the requirements needed for successful implementation. With limited guidance, water treatment decisions are likely to be unsuccessful and expend both excess time and money without the ultimate outcome of eliminating generic E. coli (non-detect per 100mL), and reducing Total Coliform bacteria (< 99 MPN/100mL). Unsuccessful treatments will likely lead to little or no reduction in potential pathogen loading in an agricultural water source and thus little to no reduction in microbiological risk. CPS-funded studies conducted by Dr. Rock characterizing microbial quality of water used to irrigate fresh produce in the Southwest found that foodborne pathogens are present in surface waters (Rock and Gerba, 2014) and that treatment options can be highly variable (Rock, 2019). Grower guidance is needed on antimicrobial agricultural water treatment options available to industry and monitoring strategies to ensure successful treatment and ultimately the protection of public health. Over the course of one growing season, the research team will evaluate the efficacy of three antimicrobial treatments (Peroxyacetic Acid - PAA, Calcium Hypochlorite, and Ultra Violet Light) across four produce growing regions of the Southwest; Yuma, AZ; Maricopa, AZ; Edinburg, TX; and Uvalde, TX. The overall goal of this proposal is to develop scientific data, which will allow produce growers to better manage their use of antimicrobial agriculture water treatments in the Southwest.