Produce Spotlight: Green Onions

Green onions, also known as scallions or spring onions are a staple on many farms and in countless kitchens. They offer fresh flavor and are often eaten raw as garnishes or in salads. However, green onions have been linked to several high-profile outbreaks and recalls in the past. This month’s spotlight highlights some of those incidents, addresses food safety challenges when growing green onions, and goes over some growing practices to keep green onions safe.

Green Onion Outbreaks and Recalls

Green onions have been associated with a variety of foodborne illness outbreaks caused by everything from viruses to bacteria. Unfortunately, recalls have been as recent as this year. Understanding previous challenges green onions have had can help grow, pack, and ship them in a manner that will keep consumers safe.

• 2025 (Listeria Recall): In September 2025, a large recall was initiated when Listeria monocytogenes was detected in green onions used in a ready-to-eat Costco Ahi Tuna Poke. Over 3,300 lbs of the poke were recalled across more than 30 states. Fortunately, there were no illnesses linked to the tainted green onions due to early detection, but Listeria is a deadly pathogen that can cause severe illness in vulnerable groups. The recall notice noted that the supplier’s green onions had tested positive for Listeria, and all product made with that batch of onions was pulled as a safety measure (Western United Fish Company Recalls Kirkland Signature Brand Ahi Tuna Wasabi Poke Because of Possible Health Risk | FDA).

• 2024 (Salmonella Recall): In October 2024, 1,271 cases of fresh green onions from a California grower were recalled due to potential Salmonella contamination. The contamination was discovered through a routine test in Canada, and fortunately no illnesses were reported. The recall spanned multiple states and Canada and included green onions sold under several and even packaged for a major retailer’s store brand. This incident shows how testing can catch contamination before people get sick (Church Brothers Farms Recall Green Onions Due to Possible Health Risk | FDA).

• 2003 & 2006 (Hepatitis A and E. coli): In 2003, contaminated scallions imported from Mexico caused a hepatitis A outbreak in Pennsylvania that sickened over 600 people and killed 3 (Taco Bell bans green onions after E coli outbreak | CIDRAP). A few years later in 2006, dozens of Taco Bell customers across the Northeast fell ill with E. coli O157:H7, prompting the chain to remove all green onions nationwide as a precaution (Taco Bell bans green onions after E coli outbreak | CIDRAP).

• Green onions have also been linked to less-publicized outbreaks: A number of reports have linked green onions to shigellosis (Shigella bacteria) and cryptosporidiosis (Cryptosporidium parasite), underscoring that scallions can harbor a variety of dangerous pathogens (Foodborne Outbreak of Cryptosporidiosis -- Spokane, Washington, 1997, Outbreaks of Shigella sonnei Infection Associated with Eating Fresh Parsley -- United States and Canada, July-August 1998). These outbreaks and recalls demonstrate that green onions can pose a food safety risk if not grown and handled properly. This makes it especially important to understand the risks involved in the whole process of growing, harvesting, packing, and transporting green onions. Once the risks are understood, adjustments can be made in the process to prevent future outbreaks or recalls.

  
  

Crop Characteristics: Why Green Onions Can Be a Food Safety Risk

Green onions have several crop traits that increase the risk of contamination. Their hollow, tubular leaves can trap water, soil, and microbes, making it difficult to reduce pathogens once exposed. If contaminated water is applied, especially through overhead irrigation, bacteria and viruses can settle into these crevices and remain hidden.

Since green onions are grown with their edible bases in direct contact with the soil, any irrigation water carrying pathogens may splash onto or soak into the harvestable portion of the crop. This risk is amplified when using untreated surface water or when irrigation occurs close to harvest. Even in hydroponic systems, research has shown green onions can internalize pathogens like E. coli and Salmonella through their roots if water sources are compromised Localization of Viable Salmonella Typhimurium Internalized through the Surface of Green Onion during Preharvest - ScienceDirect.

Taken together, these crop characteristics highlight why irrigation water assessments are essential when growing green onions. Without safe water, contamination risks increase sharply, and once present, these pathogens can be difficult to remove before the onions reach the consumer.

Best Practices for Green Onions

Learning from these outbreaks and characteristics, growers and farm managers can take proactive steps in reducing contamination risks for green onions. It is also understood that there will always be inherent risks when growing fresh produce, but there are some practices to keep in mind that can help reduce those risks.

• Use Safe Water Sources: Whenever possible, use water sources that are free of contamination. Well water or municipal water is typically less likely to harbor pathogens than surface water from ponds or canals. If using surface water be aware of upstream activities – heavy rainfall, livestock operations, or wildlife can introduce bacteria into open water.

• Optimize Irrigation Methods: Drip irrigation can help mitigate contamination if using surface water. Drip lines deliver water to the soil near the roots without wetting the above-ground portion of the onion. This greatly reduces direct contact between water and the edible leaves, in turn reducing the chance of contaminating the onions. Even when using drip irrigation there is still chances of contamination, so a risk assessment will help demonstrate the risks on each individual farm. If overhead irrigation must be used, try to do it early in the growth cycle or well before harvest time.

• Use appropriate application intervals: If you do overhead irrigate or use foliar sprays, allow an adequate interval between the last water application and harvest. Time can be an ally, many pathogens will die off on plant surfaces if given several days of dry conditions. Bacteria and virus lodes can be greatly reduced over the course of just a few days. Die-off rates can be directly affected by weather conditions, warmer and sunnier days will lead to faster die-off while cooler, humid days may slow die-off rates down. If using water sources that may be contaminated leaving 3-4 days between the final irrigation and harvest is a good idea. This allows UV sunlight and desiccation to naturally reduce microbial loads. Plan your irrigation schedule so that the crop has time to dry out before harvest when possible.

• Test and Treat Water as Needed: Regular water testing for generic E. coli (as an indicator of fecal contamination) is no longer required by the Produce Safety Rule for water used prior to harvest but is still a good practice to help understand your water quality over time. New rules offer flexibility in how growers perform water risk assessments, but knowing if your irrigation water source is prone to contamination is key. If testing reveals contamination, or if your water comes from a risky source, consider alternative methods such as switching to a safer source for any applications close to harvest.

• Worker Training: Ensure all farm workers handling green onions are properly trained in hygiene and field sanitation and understand food safety risks.

• Post-Harvest Handling: If washing or icing the onions, use water free of contaminants and add sanitizer if needed.

  
  

By understanding the risks that green onions can pose and implementing these best practices, growers can significantly reduce the chances of another outbreak. Green onions will likely remain a popular and profitable crop, but their safety depends on proper mitigation at every step, from the water we irrigate with, to the hands that harvest and pack them. The hard lessons from past outbreaks underscore a simple truth: foodborne illness is not limited to leafy greens or other commonly cited crops any crop can cause harm if we are not careful.

Sources

Centers for Disease Control and Prevention (1998, October 23). Outbreaks of Shigella sonnei infection associated with eating fresh parsley — United States and Canada, July–August 1998. Morbidity and Mortality Weekly Report. Retrieved August 21, 2025, from https://www.cdc.gov/mmwr/preview/mmwrhtml/00055338.htm

Centers for Disease Control and Prevention (1997, November 7). Foodborne outbreak of cryptosporidiosis — Spokane, Washington, 1997. Morbidity and Mortality Weekly Report. Retrieved August 21, 2025, from https://www.cdc.gov/mmwr/preview/mmwrhtml/00049714.htm

CIDRAP – Center for Infectious Disease Research and Policy (2006, December 6). Taco Bell bans green onions after E coli outbreak. Retrieved August 21, 2025, from https://www.cidrap.umn.edu/news-perspective/2006/12/taco-bell-bans-green-onions-after-e-coli-outbreak

Ge, C., Bohrerova, Z., & Lee, J. (2012, November 28). Environmental stressors influence Salmonella internalization in lettuce and green onion under simulated preharvest conditions. Journal of Food Protection, 75(11), 1965-1971. Retrieved August 21, 2025, from https://doi.org/10.4315/0362-028X.JFP-12-128

U.S. Food and Drug Administration (2024, October 21). Church Brothers Farms recall green onions due to possible health risk. Retrieved August 21, 2025, from https://www.fda.gov/safety/recalls-market-withdrawals-safety-alerts/church-brothers-farms-recall-green-onions-due-possible-health-risk

U.S. Food and Drug Administration (2025, September 15). Western United Fish Company recalls Kirkland Signature brand Ahi Tuna Wasabi Poke because of possible health risk. Retrieved August 21, 2025, from https://www.fda.gov/safety/recalls-market-withdrawals-safety-alerts/western-united-fish-company-recalls-kirkland-signature-brand-ahi-tuna-wasabi-poke-because-possible

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Article by Patrick Gordon, Produce Safety Technician