Introduction
This article highlights the best on-farm practices for leafy green safety. Kale, chard and spinach are top DFI crops and they are on our mind as they have thrived in the hoop houses this winter. This topic is part of an ongoing series to provide concise, crop specific guidance for preventing food borne illness – with DFI's own practical tips thrown in.
Consumption of leafy greens has led to hundreds of outbreaks of foodborne illness in past decades (including as recently as last fall), due to contamination from Listeria, E. coli and Salmonella (Colorado State University, 2021). Kale, chard and spinach are popular and relatively easy to grow up here in the high desert, and they are in high demand at restaurants and markets. They are eaten cooked, but also raw – which makes on-farm produce safety practices a must.
The Produce Safety Rule offers comprehensive guidance for managing the production of leafy greens. However, the science and understanding of effective practices continues to evolve as we learn more from outbreaks. The US Food and Drug Administration (FDA) released a 2020 Action Plan to improve outbreak prevention and response practices, focusing on agricultural water, compost, trace back processes and data, and consideration of adjacent land uses. The Leafy Greens Marketing Agreement (LGMA) program – the world leader in produce safety practices for greens – also recently strengthened water quality standards well beyond what is contained in current federal regulations under the Produce Safety Rule. The LGMA programs are continuing to further improve water standards and they are also looking at other practices concerning adjacent land use, compost and several other areas noted in the FDA 2020 Action Plan.
Key Practices:
- Manage potential wind and water borne pathogens from adjacent land uses, including:
1. Crop choice and placement – situate high risk crops like head lettuce so that they are protected and switch to lower risk crops if that is not possible;
2. Considering the direction of prevailing winds and installing wind breaks or hedgerows to act as a filter (check out the DFI Facebook page for info on our hedgerow);
3. Evaluating and redirecting surface water runoff from areas above crop fields that could be carrying pathogens; and
4. Establishing buffers between leafy greens and livestock – from 30 to 1200 feet depending on the number of animals according to the LGMA.
- Consider adjusting harvest timing: Determine if nearby activities taking place shortly before or during the leafy green harvest could be a contamination risk, and adjust harvest timing as needed. For example, if raw manure is applied to adjacent fields at the end of the season and around the time of leafy green harvests, you may want to move to an earlier planting/harvest.
- Monitor for freeze damage: Freeze damage in the field is of concern during shoulder or cold season production. Any openings on the leaf can attract pathogen growth, as well as causing quicker decay.
- Label leafy greens to remind consumers to wash thoroughly before eating!
There are also important general practices relevant to the safety of all vegetable and fruit crops. These include putting a broad food safety plan for the farm in place, including practices for worker health and hygiene, use of animal-based soil amendments, pre-harvest risk assessment (this entails following established procedures immediately before harvest, such as those laid in this LGMA decision tree), post-harvest handling and storage, and CDC info for consumers.
